BACKGROUND

The present invention relates to unloaders, and in particular, to an automatic semi trailer unloader.

In the shipping industry, semi-trailers are used to transport packages, parcels, envelopes, and the like on the ground. Semi-trailers can be backed up to loading docks on buildings for loading and unloading of packages, parcels, envelopes, and the like from the semi-trailer. Semi-trailers have to be manually unloaded and loaded. This is a time and labor intensive process. Sorting hubs, in particular, face challenges due to the time and labor intensive process of manually loading and unloading packages, parcels, envelopes, and the like from semi-trailers. A sorting hub is a facility that is used to sort packages, parcels, envelopes, and the like to deliver packages, parcels, envelopes, and the like to their proper destination. Typically, the packages, parcels, envelopes, and the like being received at a sorting hub are not neatly stacked on pallets for easier unloading and loading, but rather are randomized stacks of packages, parcels, envelopes, and the like. Semi-trailers with randomized stacks of packages, parcels, envelopes, and the like are time and labor intensive to unload and load.

SUMMARY

A center-pull unloader includes a center belt section with a front end and a back end, a left-hand belt section, and a right-hand belt section. A back end of the center belt section is configured to be connected to an extendable conveyor. An inner side of the left-hand belt section is connected to a first side of the center belt section. An inner side of the right-hand belt section is connected to a second side of the center belt section.

A center-pull unloader includes an incline belt with a forward end and a back end that is configured to be connected to an extendable conveyor, a center belt with a forward end and a back end connected to the forward end of the incline belt, and a center wedge with a forward end and a back end connected to the forward end of the center belt. The center-pull unloader further includes a left-hand belt with a forward end, a back end, an inward side, and an outward side, and a left-hand wedge with a forward end and a back end connected to the forward end of the left-hand belt. The inward side of the left-hand belt is connected to the incline belt. The center-pull unloader further includes a right- hand belt with a forward end, a back end, an inward side, and outward side, and a right- hand wedge with a forward end and a back end connected to the forward end of the right- hand belt. The inward side of the right-hand belt is connected to the incline belt

A center-pull unloader includes an incline belt section with a forward end and a back end, a center belt section with a forward end and a back end, a center wedge with a forward end and a back end. The back end of the incline belt section is configured to be connected to an extendable conveyor. The back end of the center belt section is connected to the forward end of the incline belt section. The back end of the center wedge is connected to the forward end of the center belt section. The center-pull unloader further includes a left-hand belt section with a forward end, a back end, an inward side, and an outward side, wherein the inward side of the left-hand belt section is connected to the incline belt section, and a left-hand wedge with a forward end and a back end, wherein the back end of the left-hand wedge is connected to the forward end of the left-hand belt section. The center-pull unloader also includes a right-hand belt section with a forward end, a back end, an inward side, and outward side, wherein the inward side of the right-hand belt section is connected to the incline belt section, and a right-hand wedge with a forward end and a back end, wherein the back end of the right-hand wedge is connected to the forward end of the right-hand belt section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a first embodiment of a center-pull unloader and an extendable conveyor.

FIG. 2 is a top isometric view of a support frame and a belt assembly of the first embodiment of the center-pull unloader.

FIG. 3 is a bottom perspective view of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 4 is a partial bottom perspective view of a front end of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 5 is a front view of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 6 is a back view of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 7 is a left-hand side view of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 8 is a right-hand side view of the support frame and the belt assembly of the first embodiment of the center-pull unloader. FIG. 9 is a top view of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 10 is a bottom view of the support frame and the belt assembly of the first embodiment of the center-pull unloader.

FIG. 11 is an isometric view of the first embodiment of a center-pull unloader.

FIG. 12 is a front view of the first embodiment of the center-pull unloader.

FIG. 13 is a back view of the first embodiment of the center-pull unloader.

FIG. 14 is a left-hand side view of the first embodiment of the center-pull unloader.

FIG. 15 is a right-hand side view of the first embodiment of the center-pull unloader.

FIG. 16 is a top view of the first embodiment of the center-pull unloader.

FIG. 17 is a bottom view of the first embodiment of the center-pull unloader.

FIG. 18 is a block diagram of a drive assembly for the first embodiment of the center-pull unloader.

FIG. 19 is a perspective view of the first embodiment of the center-pull unloader in a semi-trailer, wherein the semi-trailer is shown as being transparent.

FIG. 20 is an enlarged perspective view of the first embodiment of the center-pull unloader in a semi-trailer, wherein the semi-trailer is shown as being transparent.

FIG. 21 is a side view of the first embodiment of the center-pull unloader in a semi-trailer, wherein the semi-trailer is shown as being transparent.

FIG. 22 is an isometric view of a second embodiment of a center-pull unloader.

FIG. 23 is a front view of the second embodiment of the center-pull unloader.

FIG. 24 is a back view of the second embodiment of the center-pull unloader.

FIG. 25 is a side view of the second embodiment of the center-pull unloader.

FIG. 26 is a top view of the second embodiment of the center-pull unloader.

FIG. 27 is a bottom view of the second embodiment of the center-pull unloader.

FIG. 28 is a perspective view of the second embodiment of the center-pull unloader in a semi-trailer, wherein the semi-trailer is shown as being transparent.

FIG. 29 is an enlarged perspective view of the second embodiment of the center- pull unloader in a semi-trailer, wherein the semi-trailer is shown as being transparent.

FIG. 30 is a side view of the second embodiment of the center-pull unloader in a semi-trailer, wherein the semi-trailer is shown as being transparent.

FIG. 31 is a perspective view of a third embodiment of a center-pull unloader. FIG. 32 is a side view of the third embodiment of the center-pull unloader.

DETAILED DESCRIPTION

FIG. 1 is an isometric view of center-pull unloader 100 and extendable conveyor 102. Center-pull unloader 100 includes support frame 104, belt assembly 106, upper assembly 108, and drive assembly 110.

Center-pull unloader 100 is configured to move through a semi-trailer to pull packages in the semi-trailer onto conveyor belt 102 to which center-pull unloader 100 is attached. Center-pull unloader 100 includes support frame 104, belt assembly 106, upper assembly 108, and drive assembly 110. Support frame 104 extends underneath and alongside belt assembly 106 and provides support for belt assembly 106, upper assembly 108, and drive assembly 110. Support frame 104 rests along a floor of the semi -trailer and supports belt assembly 106, upper assembly 108, and drive assembly 110 as center- pull unloader 100 moves through the semi-trailer. Belt assembly 106 includes a plurality of belts that are configured to pull packages onto belt assembly 106 and convey packages from a front end to a back end of center-pull unloader 100.

Upper assembly 108 includes belts extending along a side of belt assembly 106 that are configured to help move packages along belt assembly 106. Upper assembly 108 further includes panels that are configured to guide packages in the semi-trailer onto belt assembly 106 of center-pull unloader 100. Center-pull unloader 100 further includes drive assembly 110. Drive assembly 110 includes electronic components, such as a battery, inverter, and control panel, and a plurality of drive motors. Drive assembly 110 is configured to cause the rotation of belts on belt assembly 106 and belts on upper assembly 108. Drive assembly 110 is further configured to drive center-pull unloader 100 through the semi-trailer.

Center-pull unloader 100 is configured to automatically unload packages in the semi-trailer. Center-pull unloader 100 can be attached to a front end of extendable conveyor 102. Packages that are gathered with center-pull unloader 100 will translate along belt assembly 106 of center-pull unloader to extendable conveyor 102 to be unloaded from the semi-trailer.

FIG. 2 is a top isometric view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 3 is a bottom perspective view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 4 is a partial bottom perspective view of a front end of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 5 is a front view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 6 is a back view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 7 is a left-hand side view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 8 is a right-hand side view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 9 is a top view of support frame 104 and belt assembly 106 of center-pull unloader 100. FIG. 10 is a bottom view of support frame 104 and belt assembly 106 of center-pull unloader 100. Center-pull unloader 100 includes support frame 104 and belt assembly 106.

Belt assembly 106 includes center incline belt 120, center wedge belts 122, center wedge 124, left-hand incline belt 126, left-hand wedge belts 128, left-hand wedge 130, right-hand incline belt 132, right-hand wedge belts 134, right-hand wedge 136, center incline belt motorized roller 138, center incline belt front drum 140, center wedge belts back drum 142, center wedge belts forward drum 144, left-hand incline belt motorized roller 146, left-hand incline belt forward drum 148, left-hand wedge belts back drum 150, left-hand wedge belts forward drum 152, right-hand incline belt motorized roller 154, right-hand incline belt forward drum 156, right-hand wedge belts back drum 158, right- hand wedge belts forward drum 160, center pulley and belt assemblies 162, left-hand pulley and belt assemblies 164, right-hand pulley and belt assemblies 166, left-hand bracket 168, and right-hand bracket 170.

Support frame 104 includes first center incline belt bracket 180, second center incline belt bracket 182, first left-hand incline belt bracket 184, second left-hand incline belt bracket 186, first right-hand incline belt bracket 188, second right-hand incline belt bracket 190, first center cross member 192, second center cross member 194, third center cross member 196, fourth center cross member 198, fifth center cross member 200, first left-hand cross member 202, second left-hand cross member 204, third left-hand cross member 206, fourth left-hand cross member 208, left-hand diagonal member 210, first right-hand cross member 212, second right-hand cross member 214, third right-hand cross member 216, fourth right-hand cross member 218, right-hand diagonal member 220, center belt bracket 222, left-hand belt bracket 224, right-hand belt bracket 226, first center wedge belts bracket 228, second center wedge belts bracket 230, first left-hand wedge belts bracket 232, second left-hand wedge belts bracket 234, first right-hand wedge belts bracket 236, second right-hand wedge belts bracket 238, x- shaped center cross member 240, x-shaped left-hand cross member 242, x-shaped right-hand cross member 244, center wedge belts roller 246, left-hand wedge belts roller 248, right-hand wedge belts roller 250, first center wedge bracket 252, second center wedge bracket 254, first left-hand wedge bracket 256, second left-hand wedge bracket 258, first right-hand wedge bracket 260, second right-hand wedge bracket 262, left-hand wheels 264, right- hand wheels 266, first center slider 268, second center slider 270, left-hand slider 272, and right-hand slider.

Belt assembly 106 includes center incline belt 120, center wedge belts 122, and center wedge 124 that form a center portion of belt assembly 106 of center-pull unloader 100. Center wedge belts 122 can also be referred to as center pull-in belts 122. Center incline belt 120 has a back end that is configured to be pivotally connected to an extendable conveyor and a forward end that is pivotally connected to center wedge belts 122. There are two center wedge belts 122 positioned next to one another. Center wedge belts 122 each have a back end that is pivotally connected to center incline belt 120 and a forward end that is pivotally connected to center wedge 124. Center wedge 124 has a back end that is pivotally connected to center wedge belts 122. Center wedge 124 tapers to an edge at a forward end. Center wedge 124 is configured to rest on the floor of a semi-trailer. Center wedge belts 122 can be flat or they can have a slight incline from center wedge 124 to center incline belt 120. Center incline belt 120 has an incline to connect center wedge belts 122 to the extendable conveyor.

Belt assembly 106 further includes left-hand incline belt 126, left-hand wedge belts 128, and left-hand wedge 130 that form a left-hand portion of belt assembly 106 of center-pull unloader 100. Left-hand wedge belts 128 can also be referred to as left-hand pull-in belts 128. Left-hand incline belt 126 has a forward end that is pivotally connected to left-hand wedge belts 128. There are two left-hand wedge belts 128 positioned next to one another. Left-hand wedge belts 128 each have a back end that is pivotally connected to left-hand incline belt 126 and a forward end that is pivotally connected to left-hand wedge 130. Left-hand wedge 130 has a back end that is pivotally connected to left-hand wedge belts 128. Left-hand wedge 130 tapers to an edge at a forward end. Left-hand wedge 130 is configured to rest on the floor of a semi-trailer. Left-hand wedge 130 is aligned with the back end of center incline belts 122. An inner left-hand wedge belt 128 and left-hand incline belt 126 have an inner side that is aligned with and connected to center incline belt 120. Left-hand wedge belts 128 and left-hand incline belt 126 have the same incline as center incline belt 120.

Belt assembly 106 further includes right-hand incline belt 132, right-hand wedge belts 134, and right-hand wedge 136 that form a right-hand portion of belt assembly 106 of center-pull unloader 100. Right-hand wedge belts 134 can also be referred to as right- hand pull-in belts 134. Right-hand incline belt 132 has a forward end that is pivotally connected to right-hand wedge belts 134. There are two right-hand wedge belts 134 positioned next to one another. Right-hand wedge belts 134 each have a back end that is pivotally connected to right-hand incline belt 132 and a forward end that is pivotally connected to right-hand wedge 136. Right-hand wedge 136 has a back end that is pivotally connected to right-hand wedge belts 134. Right-hand wedge 136 tapers to an edge at a forward end. Right-hand wedge 136 is configured to rest on the floor of a semi trailer. Right-hand wedge 136 is aligned with the back end of center incline belts 122. An inner right-hand wedge belt 134 and right-hand incline belt 132 have an inner side that is aligned with and connected to center incline belt 120. Right-hand wedge belts 134 and right-hand incline belt 132 have the same incline as center incline belt 120.

Center incline belt 120 extends around center incline belt motorized roller 138 and center incline belt forward drum 140. Center incline belt motorized roller 138 is positioned at a back end of center incline belt 120, and center incline belt forward drum 140 is positioned at a forward end of center incline belt 120. Center incline belt 120 wraps around and is driven around center incline belt motorized roller 138 and center incline belt forward drum 140. Center wedge belts 122 extend around center wedge belts back drum 142 and center wedge belts forward drum 144. Center wedge belts back drum 142 can be referred to as center pull-in belts back drum 142, and center wedge belts forward drum 144 can be referred to as center pull=in belts forward drum 144. Center wedge belts back drum 142 is positioned at back ends of center wedge belts 122, and center wedge belts forward drum 144 is positioned at forward ends of center wedge belts 122. Center wedge belts 122 wrap around and are driven around center wedge belts back drum 142 and center wedge belts forward drum 144.

Left-hand incline belt 126 extends around left-hand incline belt motorized roller 146 and left-hand incline belt forward drum 148. Left-hand incline belt motorized roller 146 is positioned at a back end of left-hand incline belt 126, and left-hand incline belt forward drum 148 is positioned at a forward end of left-hand incline belt 126. Left-hand incline belt 126 wraps around and is driven around left-hand incline belt motorized roller 146 and left-hand incline belt forward drum 148. Left-hand wedge belts 128 extend around left-hand wedge belts back drum 150 and left-hand wedge belts forward drum 152. Left-hand wedge belts back drum 150 can be referred to as left-hand pull-in belts back drum 150, and left-hand wedge belts forward drum 152 can be referred to as left- hand pull-in belts forward drum. Left-hand wedge belts back drum 150 is positioned at back ends of left-hand wedge belts 128, and left-hand wedge belts forward drum 152 is positioned at forward ends of left-hand wedge belts 128. Left-hand wedge belts 128 wrap around and are driven around left-hand wedge belts back drum 150 and left-hand wedge belts forward drum 152.

Right-hand incline belt 132 extends around right-hand incline belt motorized roller 154 and right-hand incline belt forward drum 156. Right-hand incline belt motorized roller 154 is positioned at a back end of right-hand incline belt 132, and right- hand incline belt forward drum 156 is positioned at a forward end of right-hand incline belt 132. Right-hand incline belt 132 wraps around and is driven around right-hand incline belt motorized roller 154 and right-hand incline belt forward drum 156. Right- hand wedge belts 134 extend around right-hand wedge belts back drum 158 and right- hand wedge belts forward drum 160. Right-hand wedge belts back drum 158 can be referred to as right-hand pull-in belts back drum 158, and right-hand wedge belts forward dram 160 can be referred to as right-hand pull-in belts back drum 160. Right-hand wedge belts back dram 158 is positioned at back ends of right-hand wedge belts 134, and right- hand wedge belts forward dram 160 is positioned at forward ends of right-hand wedge belts 134. Right-hand wedge belts 134 wrap around and are driven around right-hand wedge belts back dram 158 and right-hand wedge belts forward dram 160.

Center pulley and belt assemblies 162 extend between and connect center incline belt forward drum 140 to center wedge belts back drum 142. There is one center pulley and belt assembly 162 on each side of center incline belt forward drum 140 and center wedge belts back drum 142. A drive is positioned in and rotates center incline belt motorized roller 138. As center incline belt motorized roller 138 rotates, it will drive center incline belt 120, which will cause center incline belt forward dram 140 to rotate. As center incline belt forward drum 140 rotates, center pulley and belt assemblies 162 will drive center wedge belts back drum 142. As center wedge belts back drum 142 rotates, it will drive center wedge belts 122, which will cause center wedge belts forward dram 144 to rotate.

Left-hand pulley and belt assemblies 164 extend between and connect left-hand incline belt forward drum 148 to left-hand wedge belts back drum 150. There is one left- hand pulley and belt assembly 164 on each side of left-hand incline belt forward drum l48and left-hand wedge belts back dram 150. A drive is positioned in and rotates left- hand incline belt motorized roller 146. As left-hand incline belt motorized roller 146 rotates, it will drive left-hand incline belt 126, which will cause left-hand incline belt forward drum 148 to rotate. As left-hand incline belt forward drum 148 rotates, left-hand pulley and belt assemblies 164 will drive left-hand wedge belts back drum 150. As left- hand wedge belts back dram 150 rotates, it will drive left-hand wedge belts 128, which will cause left-hand wedge belts forward drum 152 to rotate.

Right-hand pulley and belt assemblies 166 extend between and connect right-hand incline belt forward dram 156 to right-hand wedge belts back drum 158. There is one right-hand pulley and belt assembly 166 on each side of right-hand incline belt forward dram 156 and right-hand wedge belts back drum 158. A drive is positioned in and rotates right-hand incline belt motorized roller 154. As right-hand incline belt motorized roller 154 rotates, it will drive right-hand incline belt 132, which will cause right-hand incline belt forward dram 156 to rotate. As right-hand incline belt forward dram 156 rotates, right-hand pulley and belt assemblies 166 will drive right-hand wedge belts back dram 158. As right-hand wedge belts back drum 158 rotates, it will drive right-hand wedge belts 134, which will cause right-hand wedge belts forward dram 160 to rotate.

Belt assembly 106 includes left-hand bracket 168 on a left-hand side of belt assembly 106, and right-hand bracket 170 on a right-hand side of belt assembly 106. Left-hand bracket 168 and right-hand bracket 170 are configured to connect belt assembly 106 to support frame 104.

Belt assembly 106 is configured to move packages from a front end to a back end of center-pull unloader 100. Center incline belt 120, center wedge belts 122, left-hand incline belt 126, left-hand wedge belts 128, right-hand incline belt 132, and right-hand wedge belts 134 are configured to rotate to pull packages from a semi-trailer onto belt assembly 106 to move the packages from the semi-trailer onto an extendable conveyor.

Support frame 104 includes first center incline belt bracket 180, second center incline belt bracket 182, first left-hand incline belt bracket 184, second left-hand incline belt bracket 186, first right-hand incline belt bracket 188, and second right-hand incline belt bracket 190. First center incline belt bracket 180 extends along a first side of center incline belt 120, and second center incline belt bracket 182 extends along a second side of center incline belt 120. First center incline belt bracket 180 and second center incline belt bracket 182 provide support for center incline belt 120. First left-hand incline belt bracket 184 extends along a first side of left-hand incline belt 126, and second left-hand incline belt bracket 186 extends along a second side of left-hand incline belt 126. First left-hand incline belt bracket 184 and second left-hand incline belt bracket 186 provide support for left-hand incline belt 126. First right-hand incline belt bracket 188 extends along a first side of right-hand incline belt 132, and second right-hand incline belt bracket 190 extends along a second side of right-hand incline belt 132. First right-hand incline belt bracket 188 and second right-hand incline belt bracket 190 provide support for right- hand incline belt 132.

First center incline belt bracket 180 is attached to second left-hand incline belt bracket 186 to attach a center portion of support frame 104 to a left-hand portion of support frame 104. Second center incline belt bracket 182 is attached to first right-hand incline belt bracket 188 to attach a center portion of support frame 104 to a right-hand portion of support frame 104.

First center cross member 192, second center cross member 194, third center cross member 196, fourth center cross member 198, and fifth center cross member 200 extend between and connect first center incline belt bracket 180 to second center incline belt bracket 182. First center cross member 192 is positioned adjacent to a back of first center incline belt bracket 180 and second center incline belt bracket 182, and fifth center cross member 200 is positioned adjacent to a front of first center incline belt bracket 180 and second center incline belt bracket 182. Second center cross member 194 is positioned between first center cross member 192 and third center cross member 196; third center cross member 196 is positioned between second center cross member 194 and fourth center cross member 198; and fourth center cross member 198 is positioned between third center cross member 196 and fifth center cross member 200. First center cross member 192 is positioned at the back of support frame 104 and is configured to be attached to an extendable conveyor.

First left-hand cross member 202, second left-hand cross member 204, third left- hand cross member 206, and fourth left-hand cross member 208 extend between and connect first left-hand incline belt bracket 184 to second left-hand incline belt bracket 186. First left-hand cross member 202 is positioned adjacent to a back of first left-hand incline belt bracket 184 and second left-hand incline belt bracket 186, and fourth left- hand cross member 208 is positioned adjacent to a front of first left-hand incline belt bracket 184 and second left-hand incline belt bracket 186. Second left-hand cross member 204 is positioned between first left-hand cross member 202 and third left-hand cross member 206; and third left-hand cross member 206 is positioned between second left-hand cross member 204 and fourth left-hand cross member 208. Left-hand diagonal member 210 extends between first left-hand incline belt bracket 184 are second left-hand incline belt bracket 186 and crosses second left-hand cross member 204. First right-hand cross member 212, second right-hand cross member 214, third right-hand cross member 216, and fourth right-hand cross member 218 extend between and connect first right-hand incline belt bracket 188 to second right-hand incline belt bracket 190. First right-hand cross member 212 is positioned adjacent to a back of first right-hand incline belt bracket 188 and second right-hand incline belt bracket 190, and fourth right-hand cross member 218 is positioned adjacent to a front of first right-hand incline belt bracket 188 and second right-hand incline belt bracket 190. Second right- hand cross member 214 is positioned between first right-hand cross member 214 and third right-hand cross member 216; and third right-hand cross member 216 is positioned between second right-hand cross member 214 and fourth right-hand cross member 218. Right-hand diagonal member 220 extends between first right-hand incline belt bracket 188 and second right-hand incline belt bracket 190 and crosses second right-hand cross member 214.

Center belt bracket 222 extends between and connects first center incline belt bracket 180 to second center incline belt bracket 182. Center incline belt 120 runs along a top side of center belt bracket 222. Left-hand belt bracket 224 extends between and connects first left-hand incline belt bracket 184 to second left-hand incline belt bracket 186. Left-hand incline belt 126 runs along a top side of left-hand belt bracket 224. Right-hand belt bracket 226 extends between and connects first right-hand incline belt bracket 188 to second right-hand incline belt bracket 190. Right-hand incline belt 132 rungs along a top side of right-hand belt bracket 226.

Support frame 104 further includes first center wedge belts bracket 228, second center wedge belts bracket 230, first left-hand wedge belts bracket 232, second left-hand wedge belts bracket 234, first right-hand wedge belts bracket 236, and second right-hand wedge belts bracket 238. First center wedge belts bracket 228, second center wedge belts bracket 230, first left-hand wedge belts bracket 232, second left-hand wedge belts bracket 234, first right-hand wedge belts bracket 236, and second right-hand wedge belts bracket 238 can also be referred to as first center pull-in belts bracket 228, second center pull-in belts bracket 230, first left-hand pull-in belts bracket 232, second left-hand pull-in belts bracket 234, first right-hand pull-in belts bracket 236, and second right-hand pull-in belts bracket 238, respectively. First center wedge belts bracket 228 is connected to first center incline belt bracket 180, and second center wedge belts bracket 230 is connected to second center incline belt bracket 182. First center wedge belts bracket 228 extends along a first side of center wedge belts 122, and second center wedge belts bracket 230 extends along a second side of center wedge belts 122. First center wedge belts bracket 228 and second center wedge belts bracket 230 provide support for center wedge belts 122. First left-hand wedge belts bracket 232 is connected to first left-hand incline belt bracket 184, and second left-hand wedge belts bracket 234 is connected to second left- hand incline belt bracket 186. First left-hand wedge belts bracket 232 extends along a first side of left-hand wedge belts 128, and second left-hand wedge belts bracket 234 extends along a second side of left-hand wedge belts 128. First left-hand wedge belts bracket 232 and second left-hand wedge belts bracket 234 provide support for left-hand wedge belts 128. First right-hand wedge belts bracket 236 is connected to first right-hand incline belt bracket 188, and second right-hand wedge belts bracket 238 is connected to second right-hand incline belt bracket 190. First right-hand wedge belts bracket 236 extends along a first side of right-hand wedge belts 134, and second right-hand wedge belts bracket 238 extends along a second side of right-hand wedge belts 134. First right- hand wedge belts bracket 236 and second right-hand wedge belts bracket 238 provide support for right-hand wedge belts 134.

X- shaped center cross member 240 extends between and connects first center wedge belts bracket 228 to second center wedge belts bracket 230. X-shaped left-hand cross member 242 extends between and connects first left-hand wedge belts bracket 232 to second left-hand wedge belts bracket 234. X-shaped right-hand cross member 244 extends between and connects first right-hand wedge belts bracket 236 to second right- hand wedge belts bracket 238.

Center wedge belts roller 246 extends between first center wedge belts bracket 228 and second center wedge belts bracket 230 adjacent a back of first center wedge belts bracket 228 and second center wedge belts bracket 230. Center wedge belts 122 roll along center wedge belt roller 246. Left-hand wedge belts roller 248 extends between first left-hand wedge belts bracket 232 and second left-hand wedge belts bracket 234 adjacent a back of first left-hand wedge belts bracket 232 and second left-hand wedge belts bracket 234. Left-hand wedge belts 128 roll along left-hand wedge belts roller 248. Right-hand wedge belts roller 250 extends between first right-hand wedge belts bracket 236 and second right-hand wedge belts bracket 238 adjacent a back of first right-hand wedge belts bracket 236 and second right-hand wedge belts bracket 238. Right-hand wedge belts 134 roll along right-hand wedge belts roller 250. Center wedge belts roller 246, left-hand wedge belts roller 248, and right-hand wedge belts roller 250 can also be referred to as center pull-in belts roller 246, left-hand pull-in belts roller 248, and right- hand pull-in belts roller 250, respectively.

Support frame 104 also includes first center wedge bracket 252, second center wedge bracket 254, first left-hand wedge bracket 256, second left-hand wedge bracket 258, first right-hand wedge bracket 260, and second right-hand wedge bracket 262. First center wedge bracket 252 is connected to first center wedge belts bracket 228, and second center wedge bracket 254 is connected to second center wedge belts bracket 230. First center wedge bracket 252 and second center wedge bracket 254 extend between center wedge belts 122 and center wedge 124. First left-hand wedge bracket 256 is connected to first left-hand wedge belts bracket 234, and second left-hand wedge bracket 258 is connected to second left-hand wedge belts bracket 234. First left-hand wedge bracket 256 and second left-hand wedge bracket 258 extend between left-hand wedge belts 128 and left-hand wedge 130. First right-hand wedge bracket 260 is connected to first right- hand wedge belts bracket 236, and second right-hand wedge bracket 262 is connected to second right-hand wedge belts bracket 238. Right right-hand wedge bracket 260 and second right-hand wedge bracket 262 extend from right-hand wedge belts 134 to right- hand wedge 136.

Left-hand wheels 264 are connected to first left-hand cross member 202. Right- hand wheels 266 are connected to first right-hand cross member 212. First center slider 268 extends along a front bottom side of first center incline belt bracket 180, and second center slider 270 extends along a front bottom side of second center incline belt bracket 182. Left-hand slider 272 extends along a front bottom side of first left-hand incline belt bracket 184. Right-hand slider 274 extends along a front bottom side of second right- hand incline belt bracket 190. As center-pull unloader 100 moves through a semi-trailer, left-hand wheels 264 and right-hand wheels 266 roll along the floor of the semi-trailer, and first center slider 268, second center slider 270, left-hand slider 272, and right-hand slider 274 slide along the floor of the semi-trailer to allow center-pull unloader 100 to easily move through the semi-trailer.

Support frame 104 provides support for belt assembly 106. Left-hand bracket 168 of belt assembly 106 is connected to first left-hand incline belt bracket 184 of support frame 104, and right-hand bracket 170 of belt assembly 106 is connected to second right- hand incline belt bracket 190 of support frame 104 to connect belt assembly 106 to support frame 104. Left-hand bracket 168 has flanges that rest in notches in first left- hand incline belt bracket 184, and right-hand bracket 170 has flanges that rest in notches in second right-hand inline belt bracket 190.

FIG. 11 is an isometric view of center-pull unloader 100. FIG. 12 is a front view of center-pull unloader 100. FIG. 13 is a back view of center-pull unloader 100. FIG. 14 is a left-hand side view of center-pull unloader 100. FIG. 15 is a right-hand side view of center-pull unloader 100. FIG. 16 is a top view of center-pull unloader 100. FIG. 17 is a bottom view of center-pull unloader 100. FIG. 18 is a block diagram of drive assembly 110 for center-pull unloader 100. Center-pull unloader 100 includes support frame 104, belt assembly 106, upper assembly 108, and drive assembly 110.

Belt assembly 106 includes center incline belt 120, center wedge belts 122, center wedge 124, left-hand incline belt 126, left-hand wedge belts 128, left-hand wedge 130, right-hand incline belt 132, right-hand wedge belts 134, right-hand wedge 136, center incline belt motorized roller 138, left-hand incline belt motorized roller 146, right-hand incline belt motorized roller 154, left-hand bracket 168, and right-hand bracket 170.

Support frame 104 includes first center incline belt bracket 180, second center incline belt bracket 182, first left-hand incline belt bracket 184, second left-hand incline belt bracket 186, first right-hand incline belt bracket 188, second right-hand incline belt bracket 190, first center cross member 192, first left-hand cross member 202, first right- hand cross member 212, left-hand wheels 264, and right-hand wheels 266.

Upper assembly 108 includes left-hand vertical belt 280, right-hand vertical belt 282, left-hand vertical belt motorized roller 284, left-hand vertical belt forward drum 286, right-hand vertical belt motorized roller 288, right-hand vertical belt forward drum 290, left-hand vertical belt frame 292, right-hand vertical belt frame 294, left-hand gas spring 296, right-hand gas spring 298, left-hand angled panel 300, left-hand side panel 302, left- hand forward panel 304, left-hand lower panel 306, left-hand lower panel wedge 308, left-hand upper panel 310, left-hand pivot points 312, right-hand angled panel 314, right- hand side panel 316, right-hand forward panel 318, right-hand lower panel 320, right- hand lower panel wedge 322, right-hand upper panel 324, right-hand pivot points 326, left-hand support rods 328, right-hand support rods 330, upper support rods 332, and damper rods 324.

Drive assembly 110 includes batter support frame 340, control panel support frame 324, inverter support frame 344, battery 350, control panel 352, inverter 354, variable frequency drives 356, center incline belt variable frequency drive motor 358, left-hand incline belt variable frequency drive motor 360, right-hand incline belt variable frequency drive motor 362, left-hand vertical belt frequency drive motor 346, and right- hand vertical belt frequency drive motor 366.

Support frame 104 and belt assembly 106 have the same structure and design as described above in references to FIGS. 2-10.

Upper assembly 108 includes left-hand vertical belt 280 and right-hand vertical belt 282. Left-hand vertical belt 280 extends along left-hand incline belt 126 from a forward end to a back end. Right-hand vertical belt 282 extends along right-hand incline belt 132 from a forward end to a back end. Left-hand vertical belt 280 extends around and is driven around left-hand vertical belt motorized roller 284 and left-hand vertical belt forward drum 286. Left-hand vertical belt motorized roller 284 is positioned at a back end of left-hand incline belt 126, and left-hand vertical belt forward drum 286 is positioned adjacent a front end of left-hand incline belt 126. Left-hand vertical belt 282 rotates to help move packages on left-hand incline belt 126 to center incline belt 120 to move the packages off of a back end of center-pull unloader 100. Right-hand vertical belt 284 extends around and is driven around right-hand vertical belt motorized roller 288 and right-hand vertical belt forward drum 290. Right-hand vertical belt motorized roller 288 is positioned at a back end of right-hand incline belt 132, and right-hand vertical belt forward drum 290 is positioned adjacent a front end of right-hand incline belt 132. Right- hand vertical belt 284 rotates to help move packages on right-hand incline belt 132 to center incline belt 120 to move the packages off of a back end of center-pull unloader 100.

Left-hand vertical belt frame 292 supports left-hand vertical belt 280, left-hand vertical belt motorized roller 284, and left-hand vertical belt forward drum 286. Right- hand vertical belt frame 294 supports right-hand vertical belt 282, right-hand vertical belt motorized roller 288, and right-hand vertical belt forward drum 290. Left-hand vertical belt frame 292 and right-hand vertical belt frame 294 provide support for and allow left- hand vertical belt 280 and right-hand vertical belt 282 to pivot outwards at a back end of center-pull unloader, respectively. Left-hand vertical belt frame 292 is attached to left- hand gas spring 296, as shown in FIG. 13. Right-hand vertical belt frame 294 is attached to right-hand gas spring 298, as shown in FIG. 13. As packages move along belt assembly 106 and push against left-hand vertical belt 280, left-hand vertical belt 280 can be pivoted outwards to allow the package to move through a back end of center-pull unloader 100. Once the package has pushed through the back end of center-pull unloader 100, left-hand gas spring 296 will push left-hand vertical belt 280 inwards. As packages move along belt assembly 104 and push against right-hand vertical belt 282, right-hand vertical belt 282 can be pivoted outwards to allow the package to move through a back end of center-pull unloader 100. Once the package has pushed through the back end of center-pull unloader 100, right-hand gas spring 298 will push right-hand vertical belt 282 inwards. As shown in FIG. 13, left-hand vertical belt 280 is pushed outwards and right- hand vertical belt 282 is in its original position.

Upper assembly 108 further includes left-hand angled panel 300, left-hand side panel 302, left-hand forward panel 304, left-hand lower panel 306, left-hand lower panel wedge 308, left-hand upper panel 310, and left-hand pivot points 312. Left-hand angled panel 300 extends along a top side of left-hand vertical belt 280. Left-hand side panel 302 is positioned at a front end of left-hand vertical belt 280 and left-hand angled panel 300. Left-hand side panel 302 extends from a back end of left-hand wedge belts 128 along a front portion of left-hand incline belt 126. Left-hand forward panel 304 is connected to a front end of left-hand side panel 302. Left-hand forward panel 304 extends from a front end to a back end of left-hand wedge belts 128. Left-hand lower panel 306 is attached to a bottom side of left-hand forward panel 304. Left-hand lower panel wedge 308 is connected to a front edge of left-hand lower panel 306. Left-hand upper panel 310 is connected to a top side of left-hand side panel 302 and sits on a top side of left-hand forward panel 304. Left-hand forward panel 304 is attached to left-hand side panel 302 at left-hand pivot points 312.

Left-hand forward panel 304 can pivot at left-hand pivot points 312 to allow center-pull unloader 100 to fit through a semi-trailer door. Left-hand forward panel 304 (and the attached left-hand lower panel 306 and left-hand lower panel wedge 308) pivot inwards when center-pull unloader 100 moves through a semi-trailer door and can then pivot outwards towards the walls of the semi-trailer once center-pull unloader 100 is positioned in the semi-trailer. Left-hand upper panel 310 will pivot at the connection to left-hand side panel 302 as left-hand forward panel 304 moves inwards and outwards. Left-hand forward panel 304 will pull packages that are along the wall of the semi-trailer inwards. Left-hand lower panel 306 and left-hand lower panel wedge 308 will lift packages on the bottom and side of the semi-trailer to push them onto left-hand wedge belts 128 of center-pull unloader 100.

Upper assembly 108 further includes right-hand angled panel 314, right-hand side panel 316, right-hand forward panel 318, right-hand lower panel 320, right-hand lower panel wedge 322, right-hand upper panel 324, and right-hand pivot points 326. Right- hand angled panel 314 extends along a top side of right-hand vertical belt 282. Right- hand side panel 316 is positioned at a front end of right-hand vertical belt 282 and right- hand angled panel 314. Right-hand side panel 316 extends from a back end of right-hand wedge belts 134 along a front portion of right-hand incline belt 132. Right-hand forward panel 318 is connected to a front end of right-hand side panel 316. Right-hand forward panel 318 extends from a front end to a back end of right-hand wedge belts 134. Right- hand lower panel 320 is attached to a bottom side of right-hand forward panel 318. Right-hand lower panel wedge 322 is connected to a front edge of right-hand lower panel 320. Right-hand upper panel 324 is connected to a top side of right-hand side panel 316 and sits on a top side of right-hand forward panel 318. Right-hand forward panel 318 is attached to right-hand side panel 316 at right-hand pivot points 326.

Right-hand forward panel 318 can pivot at right-hand pivot points 326 to allow center-pull unloader 100 to fit through a semi-trailer door. Right-hand forward panel 318 (and the attached right-hand lower panel 320 and right-hand lower panel wedge 322) pivot inwards when center-pull unloader 100 moves through a semi-trailer door and can then pivot outwards towards the walls of the semi-trailer once center-pull unloader 100 is positioned in the semi-trailer. Right-hand upper panel 324 will pivot at the connection to right-hand side panel 316 as right-hand forward panel 318 moves inwards and outwards. Right-hand forward panel 318 will pull packages that are along the wall of the semi trailer inwards. Right-hand lower panel 320 and right-hand lower panel wedge 322 will lift packages on the bottom and side of the semi-trailer to push them onto right-hand wedge belts 134 of center-pull unloader 100.

Upper assembly 106 also includes left-hand support rods 328, right-hand support rods 330, upper support rods 332, and damper rods 324. Left-hand support rods 328 are attached to and extend upwards from first left-hand incline belt bracket 184. Right-hand support rods 330 are attached to and extend upwards from second right-hand incline belt bracket 190. Upper support rods 332 extend between left-hand support rods 328 and right-hand support rods 330. Damper rods 324 are attached to upper support rods 332 and extend downwards from upper support rods 332. There are five damper rods 324 in the embodiment shown in FIGS. 11-18, but can include any number of damper rods 324 in alternate embodiments. Damper rods 324 are semi-flexible and slow the fall of packages as center-pull unloader 100 moves through a semi-trailer. In one embodiment, damper rods 324 can be made out of polypropylene plastic tubing. Drive assembly 110 includes battery support frame 340, control panel support frame 342, and inverter support frame 344. Battery support frame 340 is connected to second right-hand incline belt bracket 190 and provides support for battery 350. Control panel support frame 342 is connected to first left-hand incline belt bracket 184 and provides support for control panel 352. Inverter support frame 344 is connected to control panel support frame 324 and provides support for inverter 354.

FIG. 18 shows drive assembly 110. Battery 350 provides power for center-pull unloader 100. In an alternate embodiment, center-pull unloader 100 can be plugged into a buildings power with a cord. Battery 350 can be a 48VDC battery. Battery 350 supplies current to inverter 352. Inverter 352 can invert the 48 VDC to 480 VAC 3-phase voltage. The 480 VAC 3-phase current is then supplied from the inverter 352 to control panel 354. Control panel 354 includes a plurality of variable frequency drives 356. The variable frequency drives 356 are programmable and supply the 480 VAC current to center incline belt variable frequency drive motor 358, left-hand incline belt variable frequency drive motor 360, right-hand incline belt variable frequency drive motor 362, left-hand vertical belt frequency drive motor 346, and right-hand vertical belt frequency drive motor 366.

Center incline belt variable frequency drive motor 358 is positioned in center incline belt motorized roller 138 and drives center incline belt 120. Left-hand incline belt variable frequency drive motor 360 is positioned in left-hand incline belt motorized roller 146 and drives left-hand incline belt 132. Right-hand incline belt variable frequency drive motor 362 is positioned in right-hand incline belt motorized roller 154 and drives right-hand incline belt 132. Left-hand vertical belt frequency drive motor 346 is positioned in left-hand vertical belt motorized roller 284 and drives left-hand vertical belt 280. Right-hand vertical belt frequency drive motor 366 is positioned in right-hand vertical belt motorized roller 288 and drives right-hand vertical belt 282. Each of center incline belt variable frequency drive motor 358, left-hand incline belt variable frequency drive motor 360, right-hand incline belt variable frequency drive motor 362, left-hand vertical belt frequency drive motor 346, and right-hand vertical belt frequency drive motor 366 can independently control the speed of center incline belt 120, left-hand incline belt 126, right-hand incline belt 132, left-hand vertical belt 280, and right-hand vertical belt 282.

FIG. 19 is a perspective view of center-pull unloader 100 in semi-trailer 370, wherein semi-trailer 370 is shown as being transparent. FIG. 20 is an enlarged perspective view of center-pull unloader 100 in semi-trailer 370, wherein semi-trailer 370 is shown as being transparent. FIG. 21 is a side view of center-pull unloader 100 in semi trailer 370, wherein semi-trailer 370 is shown as being transparent. Center-pull unloader 100 includes support frame 104, belt assembly 106, upper assembly 108, and drive assembly 110. Belt assembly 106 includes center incline belt 120, center wedge belts 122, center wedge 124, left-hand incline belt 126, left-hand wedge belts 128, left-hand wedge 130, right-hand incline belt 132, right-hand wedge belts 134, and right-hand wedge 136. Upper assembly 108 includes left-hand vertical belt 280, right-hand vertical belt 282, left-hand angled panel 300, left-hand side panel 302, left-hand forward panel 304, left-hand lower panel 306, left-hand lower panel wedge 308, left-hand upper panel 310, right-hand angled panel 314, right-hand side panel 316, right-hand forward panel 318, right-hand lower panel 320, right-hand lower panel wedge 322, right-hand upper panel 324, and damper rods 324. FIGS. 19-21 further show semi-trailer 370, including semi-trailer floor 372, left-hand side wall 374, right-hand side wall 376, forward end 378, and back end 380. FIGS. 19-21 further show extendable conveyor 102 and loading dock 382. FIG. 20 shows width Wl, width Wl, and width W3. FIG. 21 shows height Hl, length Ll, and height H2. FIG. 20 also shows arrows A, arrows B, arrows C, and arrows D.

Center-pull unloader 100 has the same structure and design as described in reference to FIGS. 1-18 above. Center-pull unloader 100 is positioned in semi-trailer 370. Semi-trailer 370 includes semi-trailer floor 372 extending from a forward end to a back end of semi-trailer 370. A forward end of center-pull unloader 100 rests on semi trailer floor 372. Semi-trailer 370 further includes left-hand side wall 374 and right-hand side wall 376 extending upwards from semi-trailer floor 372. Forward end 378 extends upwards from semi-trailer floor 372 and connects left-hand side wall 374 to right-hand side wall 376. Back end 380 of semi-trailer 370 includes a door that can be opened to provide access to an interior of semi-trailer 370.

Semi-trailer 370 can be backed up to loading dock 382. Loading dock 382 is positioned in a wall of a building. Loading dock 382 includes a door that can be opened. The door of semi-trailer 370 can be aligned with the door of loading dock 372 and packages in semi-trailer 370 can be moved through the door of loading dock 372 into the building on which loading dock 372 is held. Center-pull unloader 100 is connected to extendable conveyor 102. Extendable conveyor 102 is positioned in the building but can extend through the door of loading dock 382 and the door of semi-trailer 370 and into the interior of semi-trailer 370. Center-pull unloader 100 is attached to the forward end of extendable conveyor 102 at first center cross member 192 of center-pull unloader 100 with pins. In an alternate embodiment, center-pull unloader 100 can be attached to extendable conveyor 102 using any suitable means. A back end of extendable conveyor 102 can be connected to further conveyors or to a bin for receiving packages (not shown in figures). Extendable conveyor 102 has a continuous belt. As extendable conveyor 102 is extended into semi-trailer 370, center-pull unloader 100 advances forward at the same forward travel speed as extendable conveyor 374. Center-pull unloader 100 is moved downwards so that a forward end of center-pull unloader 100 rests on semi-trailer floor 372 of semi trailer 370.

As center-pull unloader 100 moves through semi-trailer 370, the forward end of center wedge 124 can slide under packages positioned on semi-trailer floor 372. Center wedge belts 122 can then move the package from the forward end to the back end of center wedge belts 122 and onto center incline belt 120. Center incline belt 120 then moves the package from the forward end to the back end of center incline belt 120 and onto extendable conveyor 102. Extendable conveyor 102 can then move the package into the building.

The forward end of left-hand wedge 130 can slide under packages positioned on a left-hand side of semi-trailer floor 372. Left-hand wedge belts 128 can then move the packages from the forward end to the back end of left-hand wedge belts 128 and onto left- hand incline belt 126 and/or center incline belt 120. Left-hand incline belt 126 further moves the packages from the forward end to the back end of left-hand incline belt 126 and onto the center incline belt 120. Left-hand vertical belt 280 also helps to move the packages on left-hand incline belt 126 from the forward end to the back end of left-hand inline belt 126. Left-hand angled panel 300, left-hand side panel 302, left-hand forward panel 304, and left-hand lower panel 306 prevent packages from falling off the back end or the outer side of left-hand wedge belts 128 and left-hand incline belt 126. Center incline belt 120 then moves the package from the forward end to the back end of center incline belt 120 and onto extendable conveyor 102. Extendable conveyor 102 can then move the package into the building.

The forward end of right-hand wedge 136 can slide under packages positioned on a right side of semi-trailer floor 372. Right-hand wedge belts 134 can then move the packages from the forward end to the back end of right-hand wedge belts 134 and onto right-hand incline belt 132 and/or center incline belt 120. Right-hand incline belt 132 further moves the packages from the forward end to the back end of right-hand incline belt 132 and onto the center incline belt 120. Right-hand vertical belt 282 also helps move the packages on right-hand incline belt 132 from the forward end to the back end of right-hand incline belt 132. Right-hand angled panel 314, right-hand side panel 316, right-hand forward panel 318, and right-hand lower panel 320 prevent packages from falling off the back end or the outer side of right-hand wedge belts 134 and right-hand incline belt 132. Center incline belt 120 then moves the package from the forward end to the back end of center incline belt 120 and onto extendable conveyor 102. Extendable conveyor 102 can then move the package into the building.

Left-hand forward panel 304 is spring-loaded to pivot left-hand forward panel 304, left-hand lower panel 306, and left-hand lower panel wedge 308 outwards towards left-hand side wall 374 of semi-trailer 370 when center-pull unloader 100 moves through the door of semi-trailer 370. Left-hand upper panel 310 will move downwards as left- hand forward panel 304 springs outwards. Right-hand forward panel 318 is spring-loaded to pivot right-hand forward panel 318, right-hand lower panel 320, and right-hand lower panel wedge 322 outwards towards right-hand side wall 376 of semi-trailer 370 when center-pull unloader 100 moves through the door of semi-trailer 370. Right-hand upper panel 324 will move downwards as right-hand forward panel 318 springs outward. Depending on the width of semi-trailer 370, left-hand side forward panel 304 and right- hand forward panel 318 can pivot between about zero inches outwards and about four inches outwards to extend across the full width of semi-trailer 370. Left-hand lower panel wedge 308 and right-hand lower panel wedge 322 are positioned forward of left- hand wedge 130 and right-hand wedge 136, respectively, to pull packages along the sides of semi-trailer 370 inwards.

Center-pull unloader 100 will pull the center packages first, and then pull the side packages. As opposed to trying to engage the entire width of the package wall at the same time, center-pull unloader 100 enables the center packages to be lifted and pulled rearward first, allowing space in the center for the side packages to move inward. In a steady-state unloading mode, the flow of packages would be cascading toward the center and also rearward. By controlling the forward travel speed of center-pull unloader 100 and belt speeds of center incline belt 120, left-hand incline belt 126, right-hand incline belt 132, center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134, a controlled-cascade of the packages is accomplished. Damper rods 334 are included to slow the fall of the top packages in stacks of packages. Center incline belt 120, center wedge belts 122, and center wedge 124 have a width Wl of about 30 inches (762 millimeters). Left-hand incline belt 126, left-hand wedge belts 128, and left-hand wedge 130 have width W2 of about 30 inches (762 millimeters). Right-hand incline belt 132, right-hand wedge belts 134, and the right-hand wedge 136 have width W3 of about 30 inches (762 millimeters). The overall width of center-pull unloader 100 is thus about 90 inches (2,286 millimeters). Center-pull unloader 100 can have an overall height Hl of about 80 inches (2,032 millimeters) and an overall length Ll of between 7 feet (84 inches (2,134 millimeters)) and 9 feet (108 inches (2,743 millimeters)). Extendable conveyor 102 can be positioned at height H2 of about 8.25 inches (210 millimeters) off of semi-trailer floor 372.

Semi-trailers typically have doorways that are about 92 inches (2,337 millimeters) wide, thus center-pull unloader 100 is designed to fit through the doorway of the semi trailers. The inside of the semi-trailer is typically about 98 inches (2,489 millimeters) or wider. Since the rear doorway of the semi-trailer is 3 inches (76 millimeters) to 4 inches (102 millimeters) smaller in width than the body of the semi-trailer, left-hand forward panel 304 and right-hand forward panel 318 are spring-loaded outward; they will be guided through the doorway then pivot outwards to run along the side walls of the semi trailer to pull packages inward.

Center-pull unloader 100 unloads all items in the semi-trailer, and then the operator would pull the irregulars off of the belt of extendable conveyor 102 back near the chute. The operator would stop center-pull unloader 100 to manually unstack pallets, or would just let center-pull unloader 100 pull the whole pallet onto the belt and convey it rearward if it’ s not too tall to get through the door. The operator would still have to stop center-pull unloader 100, at some point, to manually unstack the pallets.

As shown in FIG. 20, extendable conveyor 102 includes a belt that moves in the direction of arrows A. Center incline belt 120 and center wedge belts 122 move in the direction of arrows B. Left-hand incline belt 126 and left-hand wedge belts 128 move in the direction of arrows C. Right-hand incline belt 132 and right-hand wedge belts 134 move in the direction of arrows D.

Extendable conveyor 102 includes a belt that moves at a speed of 18 meters/minute. Center incline belt 120 moves at a speed of 15 meters/minute. Center wedge belts 122 move at a speed of 2 meters/minute. Left-hand incline belt 126 moves at a speed of 12 minutes/minute. Left-hand wedge belts 128 move at a speed of 2 meters/minute. Right-hand incline belt 132 moves at a speed of 12 meters/minute. Right- hand wedge belts 134 move at a speed of 2 meters/minute.

Center wedge 124, left-hand wedge 130, and right-hand wedge 136 ride on semi trailer floor 372 and are pushed under the packages in semi-trailer 370. Center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134 engage the bottom rear comers of the packages and lift the packages slightly onto center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134. Center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134 move the packages onto center incline belt 120, left-hand incline belt 126, and right-hand incline belt 132, which are turning faster than center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134. The faster speed of center incline belt 120, left-hand incline belt 126, and right-hand incline belt 122 is required to allow space for all of the packages being conveyed onto center incline belt 120, left-hand incline belt 126, and right-hand incline belt 122; the multi-stage belt of extendable conveyor 102 is turning faster than center incline belt 120. In this manner, the packages change state from a 3-dimensional, static state to a single-level, in-motion state.

The force to push center wedge 124 under the wall will be one-third, or less, than trying to push a wedge under the full width of the wall at the same time. This is because, as center wedge 124 slides under the packages, the packages can lift a small amount and push outward slightly (similar to tilling soil). If the entire package wall were to be engaged at the same time, the packages would have less space to move, particularly in the outward/inward direction because all of the packages would be trying to do the same motion. The forward travel speed of center-pull unloader 100 is about 1.5 meters/minute to give center wedge 124, left-hand wedge 130, and right-hand wedge 136 time to slide under the packages.

Center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134 are turning at about 2 meters/minute; slightly faster than the forward travel speed of center-pull unloader 100 but still speed-coordinated with the forward travel speed. The reason for speed coordination with the forward travel speed is so center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134‘crawl under’ the packages. The height of center wedge 124, left-hand wedge 130, and right-hand wedge 136 and frontal height of center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134 are about one inch (25 millimeters) to about 1.5 inches (38 millimeters). They are purposely low profile so the force to push center wedge 124, left-hand wedge 130, and right-hand wedge 136 under the packages is minimized, and center wedges belts 122, left-hand wedge belts 128, and right-hand wedge belts 134 don’t lift the packages any farther than needed since that would require the packages to move upward and outward more, and that room may not be available. Package damage may also occur if the belt speeds are too high relative to forward travel speeds.

Center-pull unloader 100 is driven forward by extendable conveyor 102 in the embodiment shown in FIGS. 19-21. In an alternate embodiment, center-pull unloader 100 can include driven motors connected to left-hand wheels 264 and right-hand wheels 266 to drive left-hand wheels 264 and right-hand wheels 226, and thus center-pull unloader 100, through semi-trailer 370. The driven motors could be controlled by control panel 352.

Center-pull unloader 100 allows semi-trailers to be automatically unloaded. Manual labor is not needed to pull packages out of the semi-trailer and place them on a conveyor belt. Further, center-pull unloader 100 can unload packages from a semi-trailer more quickly than packages can be unloaded from a semi-trailer using manual labor. Center-pull unloader 100 allows semi-trailers to be unloaded with less labor and in a quicker time period that previously possible.

FIG. 22 is an isometric view of center-pull unloader 400. FIG. 23 is a front view of center-pull unloader 400. FIG. 24 is a back view of center-pull unloader 400. FIG. 25 is a side view of center-pull unloader 400. FIG. 26 is a top view of center-pull unloader 400. FIG. 27 is a bottom view of center-pull unloader 400. Center-pull unloader 400 includes belt assembly 402 and upper assembly 404. Belt assembly 402 includes center incline belt 410, center wedge belts 412, center wedge 414, left-hand incline belt 416, left-hand wedge belts 418, left-hand wedge 420, right-hand incline belt 422, right-hand wedge belts 424, and right-hand wedge 426. Upper assembly 404 includes left-hand angled panel 430, left-hand side panel 432, left-hand side roller 434, left-hand brackets 436, left-hand pivots 438, right-hand angled panel 440, right-hand side panel 442, right- hand side roller 444, right-hand brackets 446, right-hand pivots 448, and damper rods 450. Center-pull unloader 400 further includes mounting brackets 452.

Center-pull unloader 400 includes belt assembly 402 and upper assembly 404. Belt assembly 402 is configured to move along the floor of a semi-trailer to move packages in the semi-trailer onto an extendable conveyor. Upper assembly 404 is configured to guide the packages in the semi-trailer onto belt assembly 402 and the extendable conveyor. Belt assembly 402 includes center incline belt 410, center wedge belts 412, and center wedge 414 that form a center portion of belt assembly 402 of center-pull unloader 400. Center wedge belts 412 can be referred to as center pull-in belts 412. Center incline belt 410 has a back end that is configured to be pivotally connected to an extendable conveyor and a forward end that is pivotally connected to center wedge belts 412. There are two center wedge belts 412 positioned next to one another. Center wedge belts 412 each have a back end that is pivotally connected to center incline belt 410 and a forward end that is pivotally connected to center wedge 414. Center wedge 414 has a back end that is pivotally connected to center wedge belts 412. Center wedge 414 tapers to an edge at a forward end. Center wedge 414 is configured to rest on the floor of a semi-trailer. Center wedge belts 412 can be flat or they can have a slight incline from center wedge 414 to center incline belt 410. Center incline belt 410 has an incline to connect center wedge belts 412 to the extendable conveyor.

Belt assembly 102 further includes left-hand incline belt 416, left-hand wedge belts 418, and left-hand wedge 420 that form a left-hand portion of belt assembly 402 of center-pull unloader 400. Left-hand wedge belts 418 can be referred to as left-hand pull- in belts 418. Left-hand incline belt 416 has a forward end that is pivotally connected to left-hand wedge belts 418. There are two left-hand wedge belts 418 positioned next to one another. Left-hand wedge belts 418 each have a back end that is pivotally connected to left-hand incline belt 416 and a forward end that is pivotally connected to left-hand wedge 420. Left-hand wedge 420 has a back end that is pivotally connected to left-hand wedge belts 418. Left-hand wedge 420 tapers to an edge at a forward end. Left-hand wedge 420 is configured to rest on the floor of a semi-trailer. Left-hand wedge 420 is aligned with the back end of center incline belts 412. An inner left-hand wedge belt 418 and left-hand incline belt 416 have an inner side that is aligned with and connected to center incline belt 410. Left-hand wedge belts 418 and left-hand incline belt 416 have the same incline as center incline belt 410.

Belt assembly 402 further includes right-hand incline belt 422, right-hand wedge belts 424, and right-hand wedge 426 that form a right-hand portion of belt assembly 402 of center-pull unloader 400. Right-hand wedge belts 424 can be referred to as right-hand pull-in belts 424. Right-hand incline belt 422 has a forward end that is pivotally connected to right-hand wedge belts 424. There are two right-hand wedge belts 424 positioned next to one another. Right-hand wedge belts 424 each have a back end that is pivotally connected to right-hand incline belt 422 and a forward end that is pivotally connected to right-hand wedge 426. Right-hand wedge 426 has a back end that is pivotally connected to right-hand wedge belts 424. Right-hand wedge 426 tapers to an edge at a forward end. Right-hand wedge 426 is configured to rest on the floor of a semi trailer. Right-hand wedge 426 is aligned with the back end of center incline belts 412. An inner right-hand wedge belt 424 and right-hand incline belt 422 have an inner side that is aligned with and connected to center incline belt 410. Right-hand wedge belts 424 and right-hand incline belt 422 have the same incline as center incline belt 410.

Upper assembly 404 includes left-hand angled panel 430, left-hand side panel 432, left-hand side roller 434, left-hand brackets 436, and left-hand pivots 438 on a left- hand side of center-pull unloader 400. Left-hand angled panel 430 and left-hand side panel 432 extend along left-hand wedge belts 418 and left-hand incline belt 416 and are configured to guide packages on left-hand wedge belts 418 and left-hand incline belt 416 onto center incline belt 410. Left-hand angled panel 430 extends diagonally across left- hand incline belt 416 with a back end at an inner side of the back end of left-hand incline belt 416 and a forward end at an outer side of left-hand incline belt 416 near the forward end of left-hand incline belt 416. Left-hand side panel 432 extends along an outer side of a forward portion of left-hand incline belt 416 and an outer side of an outer left-hand wedge belt 418.

Left-hand side roller 434 is connected to a forward end of left-hand side panel 432 with left-hand brackets 436. Left-hand brackets 436 are connected to the forward end of left-hand side panel 432 at left-hand pivots 438. There is an upper left-hand bracket 436 and left-hand pivot 438, and a lower left-hand bracket 436 and left-hand pivot 438. Left- hand brackets 436 and left-hand side roller 434 can pivot outwards from center-pull unloader 400 at left-hand pivots 438.

Upper assembly 404 includes right-hand angled panel 440, right-hand side panel 442, right-hand side roller 444, right-hand brackets 446, and right-hand pivots 448 on a right-hand side of center-pull unloader 400. Right-hand angled panel 440 and right-hand side panel 442 extend along right-hand wedge belts 424 and right-hand incline belt 422 and are configured to guide packages on right-hand wedge belts 424 and right-hand incline belt 422 onto center incline belt 410. Right-hand angled panel 440 extends diagonally across right-hand incline belt 422 with a back end at an inner side of the back end of right-hand incline belt 422 and a forward end at an outer side of right-hand incline belt 422 near the forward end of right-hand incline belt 422. Right-hand side panel 442 extends along an outer side of a forward portion of right-hand incline belt 422 and an outer side of an outer right-hand wedge belt 424.

Right-hand side roller 444 is connected to a forward end of right-hand side panel 442 with right-hand brackets 446, which are connected to the forward end of right-hand side panel 442 at right-hand pivots 448. There is an upper right-hand bracket 446 and right-hand pivot 448, and a lower right-hand bracket 446 and right-hand pivot 448. Right-hand brackets 446 and right-hand side roller 444 can pivot outwards from center- pull unloader 400 at right-hand pivots 448.

Upper assembly 404 further includes damper rods 450, which extend from left- hand side panel 432 and right-hand side panel 442 inwards towards a center of center-pull unloader 400. As center-pull unloader 400 moves through a semi-trailer to unload packages from the semi-trailer, damper rods 450 can slow the fall of any packages that fall off of a stack of packages in the semi-trailer. There are twenty-four damper rods 450 shown in FIGS. 22-27, but any suitable number of damper rods 450 can be used in alternate embodiments.

Center-pull unloader 400 further includes mounting brackets 452. There is a first mounting bracket 452 on a first side of the back end of center incline belt 410 and a second mounting bracket 452 on a second side of the back end of center incline belt 410. Mounting brackets 452 are used to connect center-pull unloader 400 to an extendable conveyor.

FIG. 28 is a perspective view of center-pull unloader 400 in semi-trailer 460, wherein semi-trailer 460 is shown as being transparent. FIG. 29 is an enlarged perspective view of center-pull unloader 400 in semi-trailer 460, wherein semi-trailer 460 is shown as being transparent. FIG. 30 is a side view of center-pull unloader 400 in semi trailer 460, wherein semi-trailer 460 is shown as being transparent. Center-pull unloader 400 includes belt assembly 402 and upper assembly 404. Belt assembly 402 includes center incline belt 410, center wedge belts 412, center wedge 414, left-hand incline belt 416, left-hand wedge belts 418, left-hand wedge 420, right-hand incline belt 422, right- hand wedge belts 424, and right-hand wedge 426. Upper assembly 404 includes left-hand angled panel 430, left-hand side panel 432, left-hand side roller 434, left-hand brackets 436, left-hand pivots 438, right-hand angled panel 440, right-hand side panel 442, right- hand side roller 444, right-hand brackets 446, and right-hand pivots 448. Center-pull unloader 400 further includes mounting brackets 452. FIGS. 28-30 further show semi trailer 460, including semi-trailer floor 462, left-hand side wall 464, right-hand side wall 466, forward end 468, and back end 470. FIGS. 28-30 further show loading dock 472 and extendable conveyor 474. FIGS. 28-30 further show semi-trailer 460, including semi trailer floor 462, left-hand side wall 464, right-hand side wall 466, forward end 468, and back end 470. FIGS. 28-30 further show loading dock 472 and extendable conveyor 474. FIG. 29 also shows width W21, width W22, and width W23. FIG. 30 also shows height H21, length L21, and height H22. FIG. 29 shows arrows Al, arrows Bl, arrows Cl, arrows Dl, arrow El, and arrow Fl.

Center-pull unloader 400 has the same structure and design as described in reference to FIGS. 22-27 above. Damper bars 450 are not shown in FIGS. 22-27 for clarity. Center-pull unloader 400 is positioned in semi-trailer 460. Semi-trailer 460 includes semi-trailer floor 462 extending from a forward end to a back end of semi-trailer 460. A forward end of center-pull unloader 400 rests on semi-trailer floor 462. Semi trailer 460 further includes left-hand side wall 464 and right-hand side wall 466 extending upwards from semi-trailer floor 462. Forward end 468 extends upwards from semi-trailer floor 462 and connects left-hand side wall 464 to right-hand side wall 466. Back end 470 of semi-trailer 460 includes a door that can be opened to provide access to an interior of semi-trailer 460.

Semi-trailer 460 can be backed up to loading dock 472. Loading dock 472 is positioned in a wall of a building. Loading dock 472 includes a door that can be opened. The door of semi-trailer 460 can be aligned with the door of loading dock 472 and packages in semi-trailer 460 can be moved through the door of loading dock 472 into the building on which loading dock 472 is held. Center-pull unloader 400 is connected to extendable conveyor 474. Extendable conveyor 474 is positioned in the building but can extend through the door of loading dock 472 and the door of semi-trailer 460 and into the interior of semi-trailer 460.

Center-pull unloader 400 is attached to the forward end of extendable conveyor 474 with mounting brackets 452. A back end of extendable conveyor 474 can be connected to further conveyors or to a bin for receiving packages (not shown in FIGS. 28- 30). Extendable conveyor 474 has a continuous belt. As extendable conveyor 474 is extended into semi-trailer 460, center-pull unloader 400 advances forward at the same forward travel speed as extendable conveyor 474. Center-pull unloader 400 is moved downwards so that a forward end of center-pull unloader 400 rests on semi-trailer floor 462 of semi-trailer 460. As center-pull unloader 400 moves through semi-trailer 460, the forward end of center wedge 414 can slide under packages positioned on semi-trailer floor 462. Center wedge belts 412 can then move the package from the forward end to the back end of center wedge belts 412 and onto center incline belt 410. Center incline belt 410 then moves the package from the forward end to the back end of center incline belt 410 and onto extendable conveyor 474. Extendable conveyor 474 can then move the package into the building.

The forward end of left-hand wedge 420 can slide under packages positioned on a left-hand side of semi-trailer floor 462. Left-hand wedge belts 418 can then move the packages from the forward end to the back end of left-hand wedge belts 418 and onto left- hand incline belt 416 and/or center incline belt 410. Left-hand incline belt 416 further moves the packages from the forward end to the back end of left-hand incline belt 416 and onto the center incline belt 410. Left-hand angled panel 430 and left-hand side panel 432 prevent packages from falling off the back end or the outer side of left-hand wedge belts 418 and left-hand incline belt 416. Lurther, left-hand angled panel 430 guides packages on left-hand incline belt 416 onto center incline belt 410. Center incline belt 410 then moves the package from the forward end to the back end of center incline belt 410 and onto extendable conveyor 474. Extendable conveyor 474 can then move the package into the building.

The forward end of right-hand wedge 426 can slide under packages positioned on a right side of semi-trailer floor 462. Right-hand wedge belts 424 can then move the packages from the forward end to the back end of right-hand wedge belts 424 and onto right-hand incline belt 422 and/or center incline belt 410. Right-hand incline belt 422 further moves the packages from the forward end to the back end of right-hand incline belt 422 and onto the center incline belt 410. Right-hand angled panel 440 and right-hand side panel 442 prevent packages from falling off the back end or the outer side of right- hand wedge belts 424 and right-hand incline belt 422. Lurther, right-hand angled panel 440 guides packages on right-hand incline belt 422 onto center incline belt 410. Center incline belt 410 then moves the package from the forward end to the back end of center incline belt 410 and onto extendable conveyor 474. Extendable conveyor 474 can then move the package into the building.

Left-hand brackets 436 and right-hand brackets 446 are spring-loaded to pivot left-hand side roller 434 and right-hand side roller 444 outwards towards left-hand side wall 464 and right-hand side wall 466, respectively, of semi-trailer 460 when center-pull unloader 400 moves through the door of semi-trailer 460. Motors will rotate left-hand side roller 434 and right-hand side roller 444 to pull packages along left-hand side wall 464 and right-hand side wall 466, respectively, of semi-trailer 460 inwards. Depending on the width of semi-trailer 460, left-hand side roller 434 and right-hand side roller 444 can pivot between about zero inches outwards and about four inches outwards to extend across the full width of semi-trailer 460.

Center-pull unloader 400 will pull the center packages first, and then pull the side packages. As opposed to trying to engage the entire width of the package wall at the same time, center-pull unloader 400 enables the center packages to be lifted and pulled rearward first, allowing space in the center for the side packages to move inward. In a steady-state unloading mode, the flow of packages would be cascading toward the center and also rearward. By controlling the forward travel speed of center-pull unloader 100 and belt speeds of center incline belt 410, left-hand incline belt 416, right-hand incline belt 422, center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424, a controlled-cascade of the packages is accomplished. Package dampeners 450 (shown in FIGS. 22-27) are included to slow the fall of the top packages in stacks of packages.

Center incline belt 410, center wedge belts 412, and center wedge 414 have width W21 of about 30 inches (762 millimeters). Left-hand incline belt 416, left-hand wedge belts 418, and left-hand wedge 420 have width W22 of about 30 inches (762 millimeters). Right-hand incline belt 422, right-hand wedge belts 424, and the right-hand wedge 426 have width W23 of about 30 inches (762 millimeters). The overall width of center-pull unloader 400 is thus about 90 inches (2,286 millimeters). Center-pull unloader 400 can have an overall height H21 of about 80 inches (2,032 millimeters) and an overall length L21 of about 7 feet (84 inches (2,134 millimeters)). Extendable conveyor 474 can be positioned at height H22 of about 8.25 inches (210 millimeters) off of semi-trailer floor 462.

Semi-trailers typically have doorways that are about 92 inches (2,337 millimeters) wide, thus center-pull unloader 400 is designed to fit through the doorway of the semi trailers. The inside of the semi-trailer is typically about 98 inches (2,489 millimeters) or wider. Since the rear doorway of the semi-trailer is 3 inches (76 millimeters) to 4 inches (102 millimeters) smaller in width than the body of the semi-trailer, left-hand side roller 434 and right-hand side roller 444 are spring-loaded outward; they will be guided through the doorway then pivot outwards to run along the side walls of the semi-trailer to pull packages inward. Left-hand side roller 434 and right-hand side roller 444 can be positioned farther forward than is shown in FIGS. 22-30 to move the tall, thin packages that are tight against the semi-trailer wall before left-hand wedge 420 or right-hand wedge 426 gets to them.

Center-pull unloader 400 unloads all items in the semi-trailer, and then the operator would pull the irregulars off of the belt of extendable conveyor 474 back near the chute. The operator would stop center-pull unloader 400 to manually unstack pallets, or would just let center-pull unloader 400 pull the whole pallet onto the belt and convey it rearward if it’ s not too tall to get through the door. The operator would still have to stop center-pull unloader 400, at some point, to manually unstack the pallets.

As shown in FIGS. 28-30, extendable conveyor 474 includes a belt that moves in the direction of arrows Al. Center incline belt 410 and center wedge belts 412 move in the direction of arrows Bl. Left-hand incline belt 416 and left-hand wedge belts 418 move in the direction of arrows CL Right-hand incline belt 422 and right-hand wedge belts 424 move in the direction of arrows Dl. Further, a motor will rotate left-hand side roller 434 in the direction of arrow El to pull packages along left-hand side wall 464 of semi-trailer 460 inwards. A motor will rotate right-hand side roller 444 in the direction of arrow Fl to pull packages along right-hand side wall 466 of semi-trailer 460 inwards.

Extendable conveyor 474 includes a belt that moves at a speed of 18 meters/minute. Center incline belt 410 moves at a speed of 15 meters/minute. Center wedge belts 412 moves at a speed of 2 meters/minute. Left-hand incline belt 416 moves at a speed of 12 minutes/minute. Left-hand wedge belts 418 move at a speed of 2 meters/minute. Right-hand incline belt 422 moves at a speed of 12 meters/minute. Right- hand wedge belts 424 move at a speed of 2 meters/minute. Further, left-hand side roller 434 rotates at a speed of 12.5 rpm. Right-hand side roller 444 rotates at a speed of 12.5 rpm.

Center wedge 414, left-hand wedge 420, and right-hand wedge 426 ride on semi trailer floor 462 and are pushed under the packages in semi-trailer 460. Center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424 engage the bottom rear comers of the packages and lift the packages slightly onto center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424. Center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424 move the packages onto center incline belt 410, left-hand incline belt 416, and right-hand incline belt 422, which are turning faster than center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424. The faster speed of center incline belt 410, left-hand incline belt 416, and right-hand incline belt 422 is required to allow space for all of the packages being conveyed onto center incline belt 410, left-hand incline belt 416, and right-hand incline belt 422; the multi-stage belt of extendable conveyor 474 is turning faster than incline belt 410. In this manner, the packages change state from a 3 -dimensional, static state to a single-level, in-motion state.

The force to push center wedge 414 under the wall will be one-third, or less, than trying to push a wedge under the full width of the wall at the same time. This is because, as center wedge 414 slides under the packages, the packages can lift a small amount and push outward slightly (similar to tilling soil). If the entire package wall were to be engaged at the same time, the packages would have less space to move, particularly in the outward/inward direction because all of the packages would be trying to do the same motion. The forward travel speed of center-pull unloader 400 is about 1.5 meters/minute to give center wedge 414, left-hand wedge 420, and right-hand wedge 426 time to slide under the packages.

Center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424 are turning at about 2 meters/minute; slightly faster than the forward travel speed of center-pull unloader 400 but still speed-coordinated with the forward travel speed. The reason for speed coordination with the forward travel speed is so center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424‘crawl under’ the packages. The height of center wedge 414, left-hand wedge 420, and right-hand wedge 426 and frontal height of center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424 are about one inch (25 millimeters) to about 1.5 inches (38 millimeters). They are purposely low profile so the force to push center wedge 414, left-hand wedge 420, and right-hand wedge 426 under the packages is minimized, and center wedges belts 412, left-hand wedge belts 418, and right-hand wedge belts 424 don’t lift the packages any farther than needed since that would require the packages to move upward and outward more, and that room may not be available. Package damage may also occur if the belt speeds are too high relative to forward travel speeds.

Center-pull unloader 400 allows semi-trailers to be automatically unloaded. Manual labor is not needed to pull packages out of the semi-trailer and place them on a conveyor belt. Further, center-pull unloader 400 can unload packages from a semi-trailer more quickly than packages can be unloaded from a semi-trailer using manual labor. Center-pull unloader 400 allows semi-trailers to be unloaded with less labor and in a quicker time period that previously possible.

FIG. 31 is a perspective view of center-pull unloader 520. FIG. 32 is a side view of center-pull unloader 520. FIGS. 31-32 show center-pull unloader 520, extendable conveyor 522, connection mechanism 524, and semi-trailer floor 526. Center-pull unloader 520 includes incline belt 530, center belt 532, center wedge 534, left-hand belt 536, left-hand wedge 538, left-hand back panel 540, left-hand side panel 542, right-hand belt 544, right-hand wedge 546, right-hand back panel 548, right-hand side panel 550, left-hand side roller 552, left-hand brackets 554, left-hand pivots 556, left-hand motor 558, right-hand side roller 560, right-hand brackets 562, right-hand pivots 564, and right- hand motor 566. FIG. 31 also shows arrows A2, arrows B2, arrow C2, arrow D2, arrow E2, and arrow F2.

Center-pull unloader 520 is attached to the forward end of extendable conveyor 522 with connection mechanism 524. A back end of extendable conveyor 522 (not shown in FIGS. 31-32) can be connected to further conveyors or to a bin for receiving packages. Extendable conveyor 522 has a continuous belt that moves in the direction of arrows A2, as shown in FIG. 31. Connection mechanism 524 can include a hydraulic or air cylinder to move center-pull unloader 520 up and down with respect to extendable conveyor 522. As extendable conveyor 522 is extended into a semi-trailer, center-pull unloader 520 advances forward at the same forward travel speed as extendable conveyor 522. Center-pull unloader 520 is moved downwards with connection mechanism 524 so that a forward end of center-pull unloader 520 rests on semi-trailer floor 526 of the semi trailer. Connection mechanism 524 can also move center-pull unloader 520 up and down as it moves across semi-trailer floor 526 to accommodate unevenness in semi-trailer floor 526 and ensure that the forward end of center-pull unloader 520 is always resting on semi-trailer floor 526.

Center-pull unloader 520 includes incline belt 530, center belt 532, and center wedge 534 that form a center portion of center-pull unloader 520. Incline belt 530 has a back end that is pivotally connected to extendable conveyor 522 and a forward end that is pivotally connected to center belt 532. Center belt 532 has a back end that is pivotally connected to incline belt 530 and a forward end that is pivotally connected to center wedge 534. Center wedge 534 has a back end that is pivotally connected to center belt 532. Center wedge 534 tapers to a point at a forward end. A bottom of center wedge 534 rests on semi-trailer floor 526. Center belt 532 can be flat or it can have a slight incline from center wedge 534 to incline belt 530. Incline belt 530 has an incline to connect center belt 532 to extendable conveyor 522. Center belt 532 and incline belt 530 include belts that move in the direction of arrows B2, as shown in FIG. 31.

The forward end of center wedge 534 can slide under packages positioned on semi-trailer floor 526. Center belt 532 can then move the package from the forward end to the back end of center belt 532 and onto incline belt 530. Incline belt 530 then moves the package from the forward end to the back end of incline belt 530 and onto extendable conveyor 522. Extendable conveyor 522 can then move the package into a sorting facility.

Center-pull unloader 520 further includes left-hand belt 536, left-hand wedge 538, left-hand back panel 540, and left-hand side panel 542 that form a left-hand portion of center-pull unloader 520. Left-hand belt 536 has a 90 degree turn. Left-hand belt 536 is constructed so that one edge of left-hand belt 536 is shorted than the opposite edge of left- hand belt 536 such that in its natural shape it is cone shaped. Left-hand belt 536 is a continuous belt. Left-hand belt 536 has an inner side that is pivotally connected to incline belt 530 and a forward end that is pivotally connected to left-hand wedge 538. Left-hand wedge 538 has a back end that is pivotally connected to left-hand belt 536. Left-hand wedge 538 tapers to a point at a forward end. Left-hand wedge 538 is positioned backwards from center wedge 534 and is aligned with the back end of center belt 532. A bottom of left-hand wedge 538 rests on semi-trailer floor 526. Left-hand belt 536 has an incline from the forward end to a back end. The inner side of left-hand belt 536 is inclined to match the incline of incline belt 530. Left-hand belt 536 has a belt that moves in the direction of arrow C2, as shown in FIG. 31. Left-hand back panel 540 is positioned on the back end of left-hand belt 536, and left-hand side panel 542 is positioned on an outer side of left-hand belt 536.

The forward end of left-hand wedge 538 can slide under packages positioned on semi-trailer floor 526. Left-hand belt 536 can then move the package from the forward end to the inner side of left-hand belt 536 and onto incline belt 530. Left-hand back panel 540 and left-hand side panel 542 prevent packages from falling off the back end or the outer side of left-hand belt 536. Incline belt 530 then moves the package from the forward end to the back end of incline belt 530 and onto extendable conveyor 522. Extendable conveyor 522 can then move the package into a sorting facility.

Center-pull unloader 520 further includes right-hand belt 544, right-hand wedge 546, right-hand back panel 548, and right-hand side panel 550 that form a right-hand portion of center-pull unloader 520. Right-hand belt 544 has a 90 degree turn. Right- hand belt 544 is constructed so that one edge of right-hand belt 544 is shorted than the opposite edge of right-hand belt 544 such that in its natural shape it is cone shaped. Right-hand belt 544 is a continuous belt. Right-hand belt 544 has an inner side that is pivotally connected to incline belt 530 and a forward end that is pivotally connected to right-hand wedge 546. Right-hand wedge 546 has a back end that is pivotally connected to right-hand belt 544. Right-hand wedge 546 tapers to a point at a forward end. Right- hand wedge 546 is positioned backwards from center wedge 534 and is aligned with the back end of center belt 532. A bottom of right-hand wedge 546 rests on semi-trailer floor 526. Right-hand belt 544 has an incline from the forward end to a back end. The inner side of right-hand belt 544 is inclined to match the incline of incline belt 530. Right-hand belt 544 has a belt that moves in the direction of arrow D2, as shown in FIG. 31. Right- hand back panel 548 is positioned on the back end of right-hand belt 544, and right-hand side panel 550 is positioned on an outer side of right-hand belt 544.

The forward end of right-hand wedge 546 can slide under packages positioned on semi-trailer floor 526. Right-hand belt 544 can then move the package from the forward end to the inner side of right-hand belt 544 and onto incline belt 530. Right-hand back panel 548 and right-hand side panel 550 prevent packages from falling off the outer side or the back end of right-hand belt 544. Incline belt 530 then moves the package from the forward end to the back end of incline belt 530 and onto extendable conveyor 522. Extendable conveyor 522 can then move the package into a sorting facility.

Center-pull unloader 520 further includes left-hand side roller 552, left-hand brackets 554, left-hand pivots 556, left-hand motor 558, right-hand side roller 560, right- hand brackets 562, right-hand pivots 564, and right-hand motor 566. Left-hand side roller 552 is connected to a forward end of left-hand side panel 542 with left-hand brackets 554. Left-hand brackets 554 are connected to the forward end of left-hand side panel 542 at left-hand pivots 556. There is an upper left-hand bracket 554 and left-hand pivot 556, and a lower left-hand bracket 554 and left-hand pivot 556. Left-hand brackets 554 and left-hand side roller 552 can pivot outwards from center-pull unloader 520 at left-hand pivots 556. Left-hand motor 558 is connected to a top end of left-hand side roller 552 and controls the rotation of left-hand side roller 552.

Right-hand side roller 560 is connected to a forward end of right-hand side panel 550 with right-hand brackets 562. Right-hand brackets 562 are connected to the forward end of right-hand side panel 550 at right-hand side pivots 564. There is an upper right- hand bracket 562 and right-hand side pivot 564, and a lower right-hand bracket 562 and right-hand pivot 564. Right-hand brackets 562 and right-hand side roller 560 can pivot outwards from center-pull unloader 520 at right-hand side pivots 564. Right-hand motor 566 is connected to top end of right-hand side roller 560 and controls the rotation of right- hand side roller 560.

Left-hand brackets 554 and right-hand brackets 562 are spring-loaded to pivot left-hand side roller 552 and right-hand side roller 558 outwards towards the walls of the semi-trailer when center-pull unloader 520 moves through the door of the semi-trailer. Left-hand motor 558 rotates left-hand side roller 552 in the direction of arrow E2 to pull packages along the walls of the semi-trailer inwards. Right-hand motor 566 rotates right- hand side roller 558 in the direction of arrow F2 to pull packages along the wall of the semi-trailer inwards. Depending on the width of the semi-trailer, left-hand side roller 552 and right-hand side roller 554 can pivot between about zero inches outwards and about four inches outwards to extend across the full width of the semi-trailer.

Center wedge 534, left-hand wedge 538, and right-hand wedge 546 ride on semi trailer floor 526 and are pushed under the packages. Center belt 532, left-hand belt 536, and right-hand belt 544 engage the bottom rear comers of the packages and lift the packages slightly onto center belt 532, left-hand belt 536, and right-hand belt 544. Center belt 532, left-hand belt 536, and right-hand belt 544 move the packages onto incline belt 530 which is turning faster than center belt 532, left-hand belt 536, and right-hand belt 544. The faster speed of incline belt 530 is required to allow space for all of the packages being conveyed onto incline belt 530; the multi-stage belt of extendable conveyor 522 is turning at the same speed as incline belt 530. In this manner, the packages change state from a 3-dimensional, static state to a single-level, in-motion state.

Center-pull unloader 520 will pull the center packages first, and then pull the side packages. As opposed to trying to engage the entire width of the package wall at the same time, center-pull unloader 520 enables the center packages to be lifted and pulled rearward first, allowing space in the center for the side packages to move inward. In a steady-state unloading mode, the flow of packages would be cascading toward the center and also rearward. By controlling the forward travel speed of center-pull unloader 520 and belt speeds of incline belt 530, center belt 532, left-hand belt 536, and right-hand belt 544, a controlled-cascade of the packages is accomplished. It might be necessary to have package dampers (not shown) that slow the fall of the top packages. The force to push center wedge 534 under the wall will be one-third, or less, than trying to push a wedge under the full width of the wall at the same time. This is because, as center wedge 534 slides under the packages, the packages can lift a small amount and push outward slightly (similar to tilling soil). If the entire package wall were to be engaged at the same time, the packages would have less space to move, particularly in the outward/inward direction because all of the packages would be trying to do the same motion. The forward travel speed would be around 1 - 2 meters/minute to give center wedge 534, left-hand wedge 538, and right-hand wedge 546 time to slide under the packages.

Center belt 532, left-hand belt 536, and right-hand belt 544 are turning at about 1.5 - 2.5 meters/minute; slightly faster than the forward travel speed but still speed- coordinated with the forward travel speed. The reason for speed coordination with the forward travel speed is so center belt 532, left-hand belt 536, and right-hand belt 544 ‘crawl under’ the packages. The height of center wedge 534, left-hand wedge 538, and right-hand wedge 546 and frontal height of center belt 532, left-hand belt 536, and right- hand belt 544 are about one inch (25 millimeters) to about 1.5 inches (38 millimeters). They are purposely low profile so the force to push center wedge 534, left-hand wedge 538, and right-hand wedge 546 under the packages is minimized, and center belt 532, left-hand belt 536, and right-hand belt 544 don’t lift the packages any farther than needed since that would require the packages to move upward and outward more, and that room may not be available. Package damage may also occur if the belt speeds are too high relative to forward travel speeds.

Center belt 532 and center wedge 534 have a width of about 30 inches (762 millimeters). The forward end of left-hand belt 536 and left-hand wedge 538 have a width of about 30 inches (762 millimeters). The forward end of right-hand belt 544 and the right-hand 546 have a width of about 30 inches (762 millimeters). The overall width of center-pull unloader 520 is thus about 90 inches (2,286 millimeters). Semi-trailers typically have doorways that are about 92 inches (2,337 millimeters) or wider, thus center-pull unloader 520 is designed to fit through the doorway of the semi-trailers.

The inside of the semi-trailer is typically about 98 inches (2,489 millimeters) or wider. Since the rear doorway of the semi-trailer is 3 inches (76 millimeters) to 4 inches (102 millimeters) smaller in width than the body of the semi-trailer, left-hand side roller 552 and right-hand side roller 560 are spring-loaded outward; they will be guided through the doorway then pivot outwards to run along the walls of the semi-trailer to pull packages inward. Left-hand side roller 552 and right-hand side roller 560 can be positioned farther forward than is shown in FIGS. 31-32 to move the tall, thin packages that are tight against the semi-trailer wall before left-hand wedge 538 and right-hand wedge 546 gets to them.

Center-pull unloader 520 unloads all items in the semi-trailer, and then the operator would pull the irregulars off of the belt of extendable conveyor 522 back near the chute. The operator would stop center-pull unloader 520 to manually unstack pallets, or would just let the center-pull unloader 520 pull the whole pallet onto the belt and convey it rearward if it’s not too tall to get through the door. The operator would still have to stop center-pull unloader 520, at some point, to manually unstack the pallets.

Center-pull unloader 520 allows semi-trailers to be automatically unloaded. Manual labor is not needed to pull packages out of the semi-trailer and place them on a conveyor belt. Further, center-pull unloader 520 can unload packages from a semi-trailer more quickly than packages can be unloaded from a semi-trailer using manual labor. Center-pull unloader 520 allows semi-trailers to be unloaded with less labor and in a quicker time period that previously possible.

While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.