The invention relates to automated storage and dispensing systems for containers, articles and the like. More particularly, the invention relates to apparatus for storing containers and automatically advancing the containers in the storing apparatus as a container is dispensed from the apparatus. Background Art

Systems for automating the storage and distribution of containerized goods in warehousing and manufacturing facilities have been developed to reduce the expense and errors associated with manual storage and distribution. Automated storage and distribution systems, such as that described in United States Patent No. 4,621,745, can improve warehouse and manufacturing operation efficiency and inventory management.

United States Patent No. 4,621,745 discloses a container storage and dispensing assembly for use in an automated storage and distribution system. The assembly includes two opposing stacks of vertically staggered shelf assemblies. The shelf assemblies receive containers at the top of the stacks and distribute the containers in zigzag fashion downward through the stacks to a dispensing location at the bottom of the stacks.

Each shelf assembly is mounted relative to a support structure to pivot between an upwardly tilted receiving position, a substantially horizontal storage position, and a

downwardly tilted discharge position. In operation, a shelf assembly in the upwardly tilted receiving position receives a container from a next higher shelf assembly that is in the downwardly tilted discharge position. The receiving shelf assembly pivots downwardly under the weight of the container and locks in the horizontal storage position if the next lower shelf assembly is not in the receiving position.

The next lower shelf assembly assumes the receiving position when it is empty. The upper shelf assembly is unlocked from the storage position by the upward movement of the next lower shelf assembly, and is thereby permitted to pivot downwardly to the discharge position to transfer the container to the next lower shelf assembly. In this manner, the containers move downwardly through the stacks in sequential fashion until the lowermost shelf assemblies are filled with containers, and advance sequentially as containers are disposed from the bottom of the stacks.

During operation, a transferred container can topple or lodge between shelf assemblies if the receiving shelf assembly is not prevented from pivoting downwardly from the receiving position before the container is completely disposed on the receiving shelf surface. Accordingly, the descent of the receiving shelf assembly should be delayed until the container is fully received.

Static friction between a stored container and the underlying shelf surface can sometimes prevent the container from sliding off the shelf assembly during a discharge operation. The friction can be offset by increasing the

downward angle of the downwardly tilted discharge position to provide a steeper discharge slope. However, increasing the discharge tilt angle reduces the quantity of shelf assemblies that can be arranged in a stack of specified height. It would be desirable to overcome this friction without increasing the discharge tilt angle of the shelf assembly.

Disclosure of the Invention

It is an object of the invention to provide an improved shelf assembly for an automated container storage and dispensing system.

It is another object of the invention to provide a shelf assembly adapted for smooth motion to reduce wear of the components of an automated container storage and dispensing system.

It is yet another object of the invention to prevent premature downward rotation of a shelf assembly in an automated container storage and dispensing system.

It is a further object of the invention to reduce the downward discharge tilt angle required to overcome static friction between a stored container and the underlying shelf surface in an automated container storage and dispensing system.

It is a further object of the invention to provide an automated container storage and dispensing system which can operate substantially independently of the container weight. These and other objects of the invention are achieved by storage and dispensing apparatus for articles, containers and the like. The apparatus has two opposing, substantially vertical stacks of shelf assemblies mounted on support structure, such as walls, columns or a free-standing tower. Each shelf assembly includes a shelf for receiving, storing and discharging containers, and the shelves of the opposing stacks are vertically staggered relative to one another.

Each shelf is pivotally mounted relative to the support

structure for rotation between an upwardly tilted receiving position and a downwardly tilted discharge position. The free ends of the shelves of each stack extend toward the free ends of the shelves of the opposing stack. A shelf in the downwardly tilted discharge position is positioned relative to a next lower, opposing shelf in the upwardly tilted receiving position to permit the sliding transfer of a container under the influence of gravity from the upper shelf to the next lower, opposing shelf.

Containers are introduced to the shelf assemblies at or near the top of the stacks and are transferred downwardly from one shelf to the next in zigzag manner. Each container descends through the stacks until it is disposed on the lowest unfilled shelf. Containers can be selectively dispensed from a dispensing position at the bottom of the stacks.

Each shelf assembly includes biasing means or structure, such as an axial spring, for urging the shelf to the receiving position. The biasing means is adapted, however, to allow the shelf to pivot to the discharge position under the weight of a container disposed on the shelf.

Each shelf assembly also includes a transfer control moveable between a lock position and a release position. The transfer control in the lock position is adapted to retain the shelf in the receiving position or in a storage position when the next lower, opposing shelf is occupied by a container or is not in the receiving position. A mechanical, electrical or pneumatic signal is adapted to move the transfer control between the lock and release positions according to readiness

of the next lower, opposing shelf assembly to receive a container.

The shelf assembly can also include a receiving control for retaining the shelf in the receiving position until a container transferred from the next higher shelf assembly is fully received by the shelf. The receiving control prevents the shelf from descending prematurely, which can cause the container to topple or lodge between shelves.

When both the transfer control and the receiving control are provided in the shelf assembly, the shelf is retained in the receiving position or a storage position until the receiving control and the transfer control are simultaneously configured to allow the shelf to pivot downwardly. If either the receiving control or the transfer control are positioned to retain the shelf in the receiving position, the shelf cannot descend to the discharge position. Thus, the shelf assembly can prevent premature descent of the shelf before a container is fully received and can also prevent the transfer of a container to a next lower shelf that is occupied by a container or is not in the receiving position.

Each shelf assembly can alternatively include fluid- operated structure for raising the shelf to the receiving position. The raising structure is preferably embodied in a liquid or gas cylinder, although other structure known in the art could also be suitable. The raising structure can be used to lower the shelf by positive pressure or by a reduction in the fluid pressure used to raise the shelf. The raising structure is preferably an air cylinder, and most preferably

is a double acting air cylinder. The raising and lowering of the double acting air cylinder can be controlled by a cylinder control valve which selectively supplies control pressure to the top or bottom sides of an air cylinder piston. Alternatively, the raising structure is connectable to a higher pressure fluid source and to a lower pressure fluid source. The lower pressure source can be an exhaust or drain for fluid from the raising structure. Switching structure is provided for switching between the lower pressure source and the higher pressure source according to whether or not a container is present on the shelf. Each shelf assembly can include container indicator structure to provide a raising signal to the fluid-operated raising structure to raise the shelf when it is empty, and to lower the shelf when it has a container.

δ Brief Description of the Drawings

There are shown in the drawings embodiments which are presently preferred; it being understood, however, that the invention is not limited to the present arrangements and instrumentalities shown, wherein:

Figure 1 is a perspective view of a container storage and dispensing apparatus according to the invention.

Figure 2 is a side elevation view, partially broken away, depicting a first mode of operation.

Figure 3 is a side elevation view, similar to Figure 2, and depicting a second mode of operation.

Figure 4 is a top plan view of a shelf assembly according to the invention.

Fig. 5-A is a side elevation, partially broken away and partially in phantom, and depicting a first sequence of operation.

Fig. 5-B is a side elevation including schematic representation of fluid operated controls, and depicting the first sequence of operation.

Fig. 6-A is a side elevation similar to Fig. 5-A, and depicting a second sequence of operation.

Fig. 6-B is side elevation similar to Fig. 5-B, and depicting the second sequence of operation.

Fig. 7-A is a side elevation similar to Fig. 5-A and depicting a third sequence of operation.

Fig. 7-B is a side elevation similar to Fig. 5-B, and depicting the third sequence of operation. Fig. 8 is a plan view.

Fig. 9 is a schematic representation of a pneumatic control system superimposed on a schematic phantom, side elevation view of the invention, and depicting a first mode of operation.

Fig. 10 is a representation similar to Figure 9, and depicting a second mode of operation.

Fig. 11 is a representation similar to Figure 10, and depicting a third mode of operation.

Fig. 12 is a representation similar to Figure 11, and depicting a fourth mode of operation.

Fig. 13 is a top plan view.

Best Mode of Carrying Out The Invention

General Arrangement The invention relates to apparatus for vertically storing and dispensing containers, cartons, articles or the like. The apparatus can have many applications, including storing containerized goods in warehousing facilities and storing parts in manufacturing facilities.

Referring to Figs. 1-4, the container storage and dispensing apparatus includes two opposing, substantially vertical stacks of shelf assemblies 30, 32, 34 and 36 mounted on support structure. The stacks can consist of a large number of shelf assemblies, perhaps sixty, but for purposes of illustration and explanation, shelf assemblies 30, 32, 34 and 36 are shown in the drawings. The support structure can be walls or the like, but is preferably a framework, such as a free standing tower 10, which has vertical columns 12, 14, 16 and 18, laterally supported by cross members 20.

Each shelf assembly includes a shelf 40 for receiving, storing and discharging containers, and the shelves of the opposing stacks are vertically staggered relative to one another. Each shelf 40 is pivotally mounted relative to the support structure for movement between an upwardly tilted receiving position, illustrated by the shelf assemblies 30, 32 and 34, and a downwardly tilted discharge position, illustrated by the shelf assembly 36 (Fig. 1) . The free ends 37 of the shelves of each stack extend toward the opposing stack. As illustrated in Figure 3, the forward end 37 of a shelf assembly 34 in the downwardly tilted discharge position

preferably aligns with the free end 37 of a next lower, opposing shelf 36 in the upwardly tilted receiving position to allow for the smooth transfer of the container 7 under the influence of gravity from the upper shelf to the next lower, opposing shelf.

Containers are introduced to the apparatus at or near the top of the stacks. A biased ramp 39 can be provided to receive containers at the top of the apparatus and pivot under the weight of containers to transfer the containers to the first, uppermost shelf assembly 30. The containers are transferred sequentially downward in a zigzag manner through the stacks, from one shelf to the next lower shelf, and each container descends through the stacks until it is disposed on the lowest unfilled shelf. The apparatus can include a fixed, upwardly tilted dispensing ramp 38 to dispense containers discharged from the lowest shelf assembly 36 to external structure, such as a conveyor belt (not shown) .

The Preferred Shelf Assemblies

Referring to Figure 2, the uppermost shelf assembly 30 is representative of a preferred shelf assembly according to the invention.

The shelf assemblies 30, 32, 34 and 36 illustrate various modes of operation of the preferred shelf assembly and the associated position of the shelf assembly components. Accordingly, reference to particular shelf assemblies are made in connection with the particular mode of operation being discussed.

Each shelf 40 is pivotally attached to a vertical support

structure, such as between the columns 14 and 16, for movement between an upwardly tilted receiving position, as shown, and a downwardly tilted discharge position, shown by shelf assembly 34 in Fig. 3. The receiving position also serves as a storing position for the container 5 occupying the shelf 40 until the next lower shelf assembly 32 is prepared to receive the container 5. The tilt angles of the receiving and discharge positions relative to horizontal are preferably approximately 10 degrees, but can range between 5 and 20 degrees for suitable performance.

The shelf 40 can be formed by two or three shelf arms 46, which extend in parallel from the support structure to the free end 37 of the shelf 40 (Fig. 4) . Cross members 47 are mounted between and transversely to the shelf arms 46, and can have a plurality of rollers 51 to assist movement of containers across the surface of the shelf 40. The shelf arms 46 can be attached to a mounting bar 48, which is pivotally mounted between the columns 16 and 18. The mounting bar 48 can include pins 49 which extend into aligned holes in the columns 16 and 18, thereby allowing the shelf 40 to pivot vertically relative to the support structure.

The shelf assembly includes biasing means, such as spring 50, for urging the shelf 40, when empty, upwardly to the receiving position. The spring rate of the preferred biasing means 50 is selected to provide the necessary upward movement of an empty shelf, but is also selected to yield under the additional weight of a container disposed on the shelf 40, to allow the shelf 40 pivot to the discharge position. As the

shelf assembly 30 is preferably designed to accommodate a range of container weights, the biasing means 50 is preferably selected to operate within a desired range of weights, and not merely at a single weight value. The biasing means 50 is preferably an axial cylinder spring, as shown, mounted at its lower end to the support structure, and operatively connected to the shelf 40 at its upper end. Alternatively, the biasing means can be switchable mechanism, such as a solenoid or pneumatic drive for driving the shelf 40 to the receiving position when the shelf is empty, but allowing descent when a container is present on the shelf 40.

The shelf assembly 30 also includes a transfer control stop for retaining the shelf 40 in the receiving position when a container is disposed on the next lower, opposing shelf 32, or when the shelf 32 is transitioning to or from the discharge position. The transfer control is moveable between a lock position and a release position. A transfer signal, which can be mechanical, electrical or pneumatic, controls the action of the transfer control according to status of the next lower, opposing shelf assembly 32. When the next lower shelf assembly 32 is prepared to receive a container, i.e. is empty and located in the receiving position, the transfer control of the upper shelf assembly 30 is moved to the release position to allow the shelf 40 to pivot downwardly to discharge the container. When the next lower shelf assembly 32 is unprepared to receive a container, either because the shelf assembly 32 is occupied by a container or because the shelf assembly 32 is pivoting to or from the discharge position, the

transfer control of the upper shelf assembly 30 remains in the lock position to retain the shelf 40 in the receiving position.

The transfer control preferably includes a post 50 extending from the shelf 40 through a slot in a plate 52 (Fig. 4) . A roller sleeve 59 can be placed around the post 58 to provide smooth, rolling engagement between the post 58 and the slot of the plate 52 (Fig. 4) . The plate 52 is preferably mounted below the shelf 40 to the column 16 and extends upwardly, adjacent to the post 58. The plate 52 provides a slot surface 54 which defines a transfer channel 55 and a transfer stop notch 56. The post 58 moves within the channel 55 and notch 56.

When the shelf 40 of the shelf assembly 30 is in the receiving position (Fig. 2) , the post 58 is positioned in the upper end of the transfer channel 55. The plate 52 pivots downwardly under its own weight to a lock position, thereby aligning the post 58 with the transfer stop notch 56. The shelf 40 cannot pivot downwardly because the position of the post 58 in the notch 56 prohibits movement of the post 58.

The shelf 40 is retained in the receiving position until the plate 52 moves to a release position. Shelf assembly 34 (Fig. 2) illustrates the plate 52 in the release position. Movement of the plate 52 aligns the post 58 with the transfer channel 55. The curved path of the transfer channel 55 preferably corresponds to the arcuate downward path of the post 58 during descent of the shelf 40. Thus, when the post 58 is aligned with the transfer channel 55, the post 58 and

the shelf 40 to which the post 58 is connected will descend to the discharge position to transfer a container to the next lower shelf assembly 36 (Fig. 3) .

The plate 52 is moved from the lock position to the release position by an appropriate transfer signal according to the receiving status of the next lower shelf assembly. The transfer signal can be provided by a connecting rod 82 connected between the plate 52 and the next lower shelf assembly 32. The connecting rod 82 can be connected to the plate 52 through a slotted end member 84, disposed adjacent the plate 52 of upper shelf assembly 30. The end member 84 loosely surrounds a pin 86 attached to the face of the plate 52, and is adapted to slidingly and pivotally engage the pin 86 when urged by the connecting rod 82. The pin 86 is preferably mounted near the top of the plate 52 above the aperture 64, but can be attached at various locations on the plate 52.

Upward movement of the shelf assembly 36 causes associated movement of the connecting rod 82. Engagement of the end member 84 with the pin 86 moves the plate 52 upwardly to the release position shown by shelf assembly 34. The transfer stop notch 56 is moved away from the post 58, which aligns with the channel 55. The post 58 and the associated shelf 40 of the shelf assembly 34 can descend to the discharge position to transfer the container 7 to the next lower shelf assembly 36 (Fig. 3) .

The lower end of the connecting rod 82 can be connected to various parts of the next lower shelf assembly 32, but is

preferably connected to an indicator arm 60. The indicator arm 60 is pivotally mounted to the shelf 40 for movement between a forward position toward the free end 37 of the shelf 40 and a rearward position, as shown, away from the free end 37. In the preferred embodiment, the indicator arm 60 of shelf assembly 32 is urged to the forward position by the biasing means 50 when the shelf assembly 32 is empty. When a container 6 is disposed on the shelf assembly 32, the container engages a cross bar 69 (Fig. 4) of the indicator arm 60, and moves the indicator arm 60 to the rearward position against the force of the biasing means 50. Thus, the position of the indicator arm 60 is dependent upon the presence of a container on the shelf assembly 32.

The connecting rod 82 communicates the position and the associated status of the next lower shelf assembly 32 to the plate 52 of the upper shelf assembly 30. When the next lower shelf assembly 32 is occupied by a container, the indicator arm 60 is retracted to the rearward position, and the connecting rod 82 does not urge the slotted end member 84 to engage the plate pin 86. Accordingly, the plate 52 of the shelf assembly 30 remains in the lock position.

Similarly, when the next lower shelf assembly 32 is transitioning to or from the discharge position, the plate 52 of the upper shelf assembly 30 should remain in the locked position. The connecting rod 82 and the end member 84 are preferably selected to move with the next lower shelf assembly 32 during transitioning to and from the discharge position without affecting the plate 52 of the upper shelf assembly 30.

Now referring to the lower shelf assemblies 34 and 36 in Fig. 2, the shelf assembly 36 is prepared to receive a new container, such as container 7, because the shelf assembly 36 is located in the receiving position and is empty. Accordingly, the indicator arm 60 is urged to the forward position by the biasing structure 50. As the indicator arm 60 is driven toward the forward position, the connecting rod 82 moves upwardly, thereby urging the slotted end member 84 to engage pin 86 of the shelf assembly 34. The plate 52 is moved to the release position shown, thereby allowing the tray to pivot to the discharge position to transfer a container (Fig. 3).

The preferred shelf assembly 30 also provides a receiving control for retaining the shelf 40 in the receiving position until a container being transferred from a next higher shelf assembly is completely disposed on the shelf surface. The receiving control prevents the shelf 40 from descending prematurely, which can cause the transferred container to topple or lodge between shelf assemblies.

The receiving control is preferably integrated into the plate 50. A receiving stop channel 67 is formed by a slot 64, which also defines a receiving stop recess 66. A receiving stop pin 62 extends from the indicator arm 60 through the slot 64 formed in the plate 52 (Fig. 4) . The receiving stop pin 62 is preferably surrounded by a roller sleeve 61 for smooth, rolling engagement between the slot 64 and pin 62. The receiving stop recess 66 prohibits movement of the receiving stop pin 62. The receiving stop channel 67 preferably

coincides with the downward arcuate path of the receiving stop pin 62 to permit the descent of the shelf 40 when the receiving stop pin 62 is aligned with the receiving stop channel 67.

Referring to the shelf assembly 36 in Fig. 2, when the shelf 40 is empty, the indicator arm 60 is driven to the forward position, toward the free end 37, by the biasing means 50. Correspondingly, the receiving stop pin 62 is positioned in the receiving stop recess 66 of the slot 64. The plate 52 blocks the downward arcuate path of the receiving stop pin 62 required for downward pivoting of the shelf 40.

As the indicator arm 60 pivots to the rearward position, the receiving stop pin 62 leaves the receiving stop recess 66 and aligns with the channel 67, which permits descent of the receiving stop pin 62 and the shelf 40. Thus, the receiving stop will retain the shelf 40 in the receiving position until a container is completely disposed on the shelf.

The transfer control and the receiving control are preferably provided integrally, such that the shelf 40 of shelf assembly 30 is retained in the receiving position until a container is fully received and further until the next lower shelf assembly 32 is prepared to receive a container. This can be accomplished by providing the single plate 52 having both the transfer channel 55 and the receiving channel 67. Thus, the preferred shelf assembly provides a dual stop arrangement in which movement of a plate relative to a pin controls descent according to the readiness of a next lower shelf and the movement of a pin relative to the plate controls

descent of the shelf according to the presence of a container on the shelf. This assembly provides reliable coordinated operation of the shelf assembly with minimal structural components.

The preferred shelf assembly can also be adapted to provide a discharge drive means for overcoming friction between a stored container and the underlying shelf surface during transfer operations. The discharge drive means should include a driving member for imparting force on the container toward the free end of the shelf as the shelf pivots to the discharge position. The driving member preferably imparts a continuous force to the container during the descent of the shelf. However, an initial, impulsive force to the container can be sufficient to overcome static friction when the downward tilt angle of the shelf is selected to overcome the remaining kinetic friction between the container and the underlying shelf surface as the container is transferred.

In the preferred shelf assembly, the driving member is the indicator arm 60 and cross bar 69. Referring to Fig. 2, the indicator arm 60 of shelf assembly 34 is positioned relative to the plate 52 to permit descent of shelf 40. As the shelf 40 and the indicator arm 60 descend, the biasing means 50 urges the indicator arm 60 forward towards the free end 37 of shelf 40. The forward rotation of the indicator arm drives the container 7 towards the free end, thereby overcoming static friction between the container 7 and the underlying surface of shelf 40. Thus, the components of the preferred shelf assembly can not only control the position of

the shelf but can also simultaneously serve to overcome the static friction between a stored container and the underlying surface during the transfer operations without increasing the downward tilt angle of the shelf in the discharge position. When the receiving stop means is in the releasing rearward position but the transfer stop means is in the lock position, the receiving stop pin 62 should be secured in the full rearward position to avoid false signals to the next higher shelf assembly.

As discussed above, the connecting rod 82 controls the transfer stop means of shelf assembly 30 according to the location of the indicator arm 60 of the next lower shelf assembly 32. A forward position of the indicator arm 60 indicates the shelf 40 is empty, and a rearward position of the indicator arm 60 indicates that a container is occupying the shelf 40. Accordingly, the indicator arm 60 of the next lower shelf assembly 32 should be accurately positioned to adequately represent the presence or absence of a container on the shelf 40. Positions of the indicator arm 60 between the forward and rearward locations can create ambiguous signals to the connecting rod 82, causing the connecting rod 82 to prematurely activate the transfer stop means of the upper shelf assembly 30 or to fail to release the upper shelf assembly 30.

The initial impact of a received container with the cross bar 69 drives the indicator arm 60 to the rearward position. If the forward force exerted by the biasing structure 50 is greater than the weight component applied to the indicator arm

60 by the container, the indicator arm 60 can settle at an intermediate position between the forward and rearward positions. Each shelf assembly therefore preferably provides a latch 70 to secure the receiving stop pin 62 and the indicator arm 60 in the rearward position upon receipt of a container. Referring to the shelf assembly 30, the latch 70 is preferably pivotally mounted to the shelf 40 and extends toward the free end 37. A free end 71 of the latch 70 provides a sloped surface for engaging the receiving stop pin 62. As the receiving stop pin 62 moves rearwardly, the sloped surface raises the latch 70.

In the shelf assembly 30, the indicator arm 60 has been partially broken away to illustrate the interaction of the latch 70 with the receiving stop pin 62. When the receiving stop pin 62 reaches a latch corner 65, located at the upper end of the channel 67, the latch 70 pivots downwardly under its own weight and secures the receiving stop pin 62 in the latch corner 65 by a shoulder 73. When the shelf 40 and associated receiving stop pin 62 descend to the discharge position, the latch 70 is preferably prevented from following by a retaining pin 75 extending from the face of the plate 52. In the shelf assemblies 32 and 34, the latch 70 has been partially removed so as not to interfere with the clarity of the surrounding structure for illustration and explanation purposes.

Operation

Referring to Fig. 1, a container, such as container 9, can be selectively dispensed from the storing and dispensing

apparatus by release of the lowermost shelf assembly 36. A solenoid 22 can be provided to move the plate 52 to the release position, thereby permitting the descent of shelf 40 to the discharge position. The container 9 is transferred from the shelf assembly 36 to the dispensing ramp 38 for delivery to external structure, such as a conveyor belt.

Referring to Fig. 2, when the container 9 has been discharged, the shelf 40 of shelf assembly 36 is urged to the receiving position by a biasing means 50. When the post 58 reaches the upper portion of channel 55, the plate 52 moves downwardly to secure the post 58 and the transfer stop notch 56. Simultaneously, the indicator arm 60 is rotated forward by the biasing structure 50 to the forward position toward the free end 37. Thus, the shelf assembly 36 is configured to receive a container as it is in the receiving position and is empty. The forward position of the indicator arm 60 in relation to the upwardly tilted receiving position of the shelf 40 moves the connecting rod 82 and the end member 84 into sliding engagement with the pin 86 on plate 52 of the upper shelf assembly 34. The plate 52 is thereby moved to the release position, aligning the post 58 with the transfer channel 55. As the shelf assembly 34 is presently occupied by a container 7, the indicator arm 60 is in the rearward position, thereby aligning the receiving stop pin with the receiving stop channel 67. Thus, the post 58 and the receiving stop pin 62 are aligned in their respective channels 55 and 67 to permit the downward pivot of the shelf 40.

Referring to Fig. 3, the shelf 40 of shelf assembly 34

pivots downwardly to the discharge position to transfer container 7 to shelf assembly 36. During the descent, the indicator arm 60 is pivoted forwardly by the biasing structure 50 to drive the container 7 toward the free end 37 of shelf 40. This forward drive overcomes static friction between the container 7 and the surface of shelf 40 to provide smooth transfer of the container 7 to shelf assembly 36.

The above-described transfer operation continues sequentially between shelf assemblies 32 and 34 and shelf assemblies 30 and 32 until containers are transferred to the lowest unfilled shelf.

Thus, the preferred storage and dispensing apparatus includes shelf assemblies for selectively dispensing and automatically advancing containers through the shelf assembly stack with shelves having only an upwardly tilted receiving and storage position and a downwardly tilted discharge position.

There is shown in the Figs. 5-8 an alternative embodiment including a plurality of shelf assemblies with shelves 120- 123. Each shelf is pivotally mounted to vertical support structure such as the posts 128, 129. The shelves 120-123 are pivotable between at least an upwardwardly tilted, receiving position and a downwardly tilted, discharge position, as illustrated respectively by the shelves 120, 121 in Fig. 5-A.

The construction of the shelves can vary widely. In one construction, each shelf is comprised of a series of parallel support plates 132 (Fig. 8) which are joined at an axle 134. The axles 134 can be mounted to the posts 128, 129 about

mounting pins 144. Cross bars 136 are mounted through the support plates 132 and can have a plurality of rollers 140 to assist the transfer of containers onto or off of the shelves. The raising structure is preferably a pneumatic cylinder 152 which is mounted at one end to a shelf, and at another end to fixed structure such as the support posts 128, 129. A source of high pressure fluid 156 is provided to supply raising pressure to the cylinder 152. In one embodiment, a path 158 provides a high pressure fluid to a port 160 of the cylinder 152 (Fig. 5-B) . High pressure fluid entering the port 160 drives a piston 162 and piston arm 164 to extend the cylinder 152 and raise the corresponding shelf. A lower pressure source 170 can be provided as a drain or exhaust for high pressure fluid from the cylinder 152 to permit lowering of the shelf under the weight of the shelf and an associated container. This drain or exhaust could be at or near atmospheric pressure. The source 170 can return fluid to a suitable pump for repressurization to the higher pressure.

Container indicator switching structure is provided for lowering the cylinder and the shelf when a container is received on the shelf. In a preferred embodiment, the switching structure includes a valve 176 which has at least two positions. In one position, the valve connects the path 158 to the high pressure source 156 through a high pressure path 172. In a second position, the valve 176 connects the path 158 to the low pressure source 170 through a low pressure path 174. Actuation of the valve 176 can be provided by

suitable structure which senses the presence of the container. In one embodiment, a switch arm 180 is associated with the surface of a shelf, whereby a container transferred to the shelf will strike the switch 180 to actuate the valve from a connection to the high pressure source 156, to a connection to the lower pressure source 170. This will provide a lowering signal to the associated cylinder 152 when a container is received on the shelf.

The high pressure source and low pressure source can operate at various pressures. The precise pressures will largely depend on the weight of the container and the associated weight of the shelf, as well as the mechanical characteristics of the components, particularly the fluid- operated raising structure. The low pressure source 170 can be an exhaust or drain for the high pressure fluid from the cylinder 152. The flow of fluid entering the low pressure source 170 from the cylinder 152 can be controlled by the use of a flow valve, such as a needle valve, or by the pressure of the low pressure source 170 to control the rate at which the container is lowered. This will help to prevent jarring and vibrations, particularly where heavy containers are present. Fluid leaving the cylinder 152 can exit through the port 160. It may be desirable to meter some fluid through a port 182 to the opposite side of the piston to facilitate the lowering process. Other fluid connections are also possible.

A transfer control is operatively connected between each shelf and the next lower shelf. The transfer control prevents the lowering of a shelf to the discharge position unless the

next lower shelf is in the receiving position. A presently preferred embodiment of the transfer control includes a movable transfer stop member 190. The transfer stop member 190 is adapted to contact a portion of the shelf to prevent the shelf from pivoting to the discharge position, and to be moved from engagement with the shelf when the next lower shelf is prepared to receive a container. The transfer stop member 190 can be pivotally mounted to a fixed object such as the support posts 128, 129. A support 194 can be fixed to the support posts 128, 129 to provide a fixed surface for mounting the transfer stop member. The transfer stop member 190 is preferably pivotally mounted on the support 194. In a preferred embodiment, a cam plate 198 is provided which is fixed to the shelf and thereby pivots with the shelf. An abutment portion 200 of the cam plate 198 is adapted to engage a first seat 202 of the transfer stop member to prevent the shelf from pivoting to the discharge position.

The transfer stop member is actuated according to the position of the next lower shelf to move out of engagement with the first abutment portion 200 so as to permit the upper shelf to pivot downwardly to the discharge position. This will occur only when the next lower shelf is in the upwardly tilted, receiving position. In a preferred embodiment, a connecting rod 206 is attached to the transfer stop member 190 and to the next lower shelf. The connection to the next lower shelf can be through any suitable structure, such as the connecting arm 210 which is fixed to and extends upwardly from each shelf. A pin in the connecting arm can be engaged to a

slotted fitting 212 of the connecting rod 206 to permit sliding movement. Pivoting of the next lower shelf to the upwardly tilted, receiving position causes rearward movement of the connecting arm 210 and similar movement of the connecting rod 206. The transfer stop member 190 is moved out of engagement with the abutment portion 200 of the cam plate 198, to permit downward movement of the shelf to the receiving position. A second seat 216 can be provided on the transfer stop member 190 which can be engaged to provide the lower limit of movement of the shelf in the discharge position.

Some downward pivoting of the shelf can occur when a container has been received, such that the container is stored in an intermediate storage position. The orientation of the first abutment portion 200 of the cam plate 198 to the first seat 202 of the transfer stop 190 can be such that downward pivoting of the shelf will occur prior to contact between the first abutment portion 200 and the first seat 202.

A transfer stop spring 218 can be utilized to urge the transfer stop member 190 into engagement with the cam plate 198. Preferably, downward movement of the shelf will cause contact between the transfer stop 190 and a cam surface 219 of the cam plate 198 to provide a smooth transfer to the discharge position.

A second abutment portion 220 of the cam plate 198 can be utilized to limit upward movement of the shelf during the raising process. The second abutment portion can contact a fixed object, which preferably is a portion 224 of the transfer stop member 190, to limit the upward movement of each

shelf .

Latching structure is preferably provided to secure the shelf in the receiving position until a container has been fully received on the shelf. The latching structure can take several alternative forms. In a presently preferred embodiment, a latch arm 230 is pivotally mounted to each shelf, as about a pivot pin 236. A latch seat 240 can be fixed to the support 194 such that, when the shelf is in the receiving position, a dog-leg portion 242 of the latch arm 230 rests on the latch seat 240 to support the shelf in the receiving position. A latch spring 244 can be provided to urge the dog-leg portion of the latch arm into engagement with the latch seat 240. A portion of the latch arm 230 extends above the shelf, and a cross bar 248 can extend transversely over a rear portion of the shelf. A container that has been fully received onto the shelf will strike the cross bar 248 and pivot the latch arm 230 out of engagement with the latch seat 240. This will permit the shelf to pivot downwardly to the intermediate storage position wherein the abutment portion 200 of the cam plate 198 rests on the first seat 202 of the transfer stop member 190.

In operation, the bottom-most shelf 120 will have a container and is caused to pivot downwardly by operation of a suitable control mechanism such as the solenoid 250. The solenoid 250 operates to pivot the transfer stop 190 to release the shelf 120, which will pivot downwardly to the discharge position to discharge the container from the tower. A fixed exit ramp 254 can be provided to direct the container

onto a conveyor or other structure.

Following the discharge of the container, the switch member 180 will be released and the valve 176 will be actuated to connection with the high pressure source 156. High pressure fluid will be applied through the path 158 to the cylinder 152 to extend the cylinder and raise the shelf 120 to the position shown in Fig. 5-B. The dog-leg portion 242 of the latch arm 230, under the influence of the latch spring 244, will be moved into engagement with the latch seat 240 to secure the shelf 120 in the receiving position. Upward pivoting of the shelf 120 will cause corresponding rearward movement of the connecting arm 210 and connecting rod 206 (Fig. 5-A) . The transfer stop member 190 associated with the shelf 121 will be pivoted such that the first seat 202 will be moved from engagement with the abutment portion 200 of the associated cam plate 198. The shelf 121 will pivot downwardly under the weight of container 260 until the abutment portion 200 contacts the second seat 216 of the transfer stop member 190, which defines the lower limit of the discharge position. The container 260, when received fully on the shelf 120, will strike the cross bar 248 of the latch arm 230 at the rear of the shelf so as to pivot the latch arm out of engagement with the latch seat 240. Also, the container 260 will contact the switch 180 on the shelf 120 to cause the valve 176 to move to connection with the low pressure source 170. This will drain high pressure fluid from the cylinder 152 to permit the shelf 120 to pivot downwardly to the intermediate storage position in which the abutment portion 200 of the cam plate 198 is in

engaged to the first seat 202 of the transfer stop member 190

(Figs. 6-A, 6-B.)

Discharge of the container 260 from the shelf 121 causes the release of the associated switch 180 and actuation of the valve 176 to connection with the high pressure source 156. The shelf 121 will be raised to the receiving position shown in Fig. 6-A. Pivoting of the shelf 121 to the receiving position will cause movement of the connecting arm 210 and connecting rod 206, to pivot the first seat 202 of the transfer stop member 190 that is associated with the shelf 122 out of engagement with the corresponding abutment portion 200 of the cam plate 198. The shelf 122 will rotate downwardly under the weight of the container 261 to the discharge position in which the first abutment portion 200 of the cam plate 198 contacts the second seat 216. The container 261 will thereby be transferred from the shelf 122 to the shelf 121.

Transfer of the container 261 to the shelf 121 will depress the switch 180 associated with the shelf 121 to actuate the valve 176 to a connection with the low pressure source 170. Also, the container 261 will strike the latch arm 230 to move it out of engagement with the latch seat 240 (Fig. 7-A) . These conditions will permit downward pivoting of the shelf 121 to the intermediate storage position. Removal of the container 261 from the shelf 122 will release the switch 180 associated with that shelf and connect the corresponding valve 176 to the high pressure source 156. This will raise the shelf to the receiving position shown in Fig. 7-A.

Movement of the corresponding connecting rod 206 will cause the shelf 123 to pivot downwardly to the discharge position to transfer the container 262 to the shelf 122.

The above-described process will continue up the tower until all containers have been transferred downwardly through the tower to the lowest available shelf. Similarly, containers loaded at the top of the tower will be transferred downwardly through the tower to the lowest available shelf.

This embodiment of the invention can take many alternative forms. The connecting rod 206, for example, can be replaced by corresponding electrical or fluid-operated control apparatus. The latch arm can be constructed according to several alternative designs which will accomplish this function. The cam plate and transfer stop member can likewise be modified to many designs, or replaced with alternative structure which will perform the necessary functions described herein.

The precise dimensions of the components are selected for the particular containers that are to be stored in the tower. The shelves preferably pivot upwardly and downwardly approximately 10 degrees from the horizontal, while the intermediate storage position preferably defines an angle of approximately 5 degrees upward from the horizontal. Operating pressure of 80 psig for the high pressure and 50 psig for the low pressure have been utilized, although pressures for a given application can vary widely. The cylinder 152 can have an inside bore of approximately 1 1/2", although this also will vary widely with the particular application.

Referring to Figs. 9-13, there is shown a completely fluid-operated embodiment of the invention. The container storage and dispensing system generally includes two opposing, substantially vertical stacks of staggered shelf assemblies 290, 292, 294 and 296 mounted on support structure, for example, columns 302 and 304. The columns can be laterally supported by cross members. Each shelf assembly includes a shelf 300 for receiving, storing and discharging containers. Each shelf 300 is pivotally mounted relative to the support structure for movement at least between an upwardly tilted receiving position, illustrated by the shelf assembly 296, and a downwardly tilted discharge position, illustrated by the shelf assembly 294 (Fig. 12) . One or more intermediate storage positions are also possible.

The shelf assemblies 290, 292, 294 and 296 illustrate various modes of operation of this embodiment and the associated position of the shelf assembly components. Accordingly, reference to particular shelf assemblies are made in connection with the particular mode of operation being discussed.

Each shelf 300 is pivotally attached to the vertical support structure, such as between the columns 302 and 304, for movement at least between an upwardly tilted receiving position, as shown, and a downwardly tilted discharge position. A raising means such as a pneumatic air cylinder is provided for driving the shelf 300 to the receiving position when the shelf is empty, but allowing descent when a container is present on the shelf 300. The receiving position can also

serve as a storing position for a container, as illustrated in Fig. 9. The container will occupy a shelf until the next lower shelf assembly is prepared to receive the container. The tilt angles of the receiving and discharge positions relative to horizontal can be varied, but preferably are between 5 and 20 degrees. One or more intermediate storage positions, preferably at or near the horizontal, are also possible.

Each shelf assembly includes transfer control structure which prevents lowering of the shelf 300 to the discharge position when a container is disposed on the next lower, opposing shelf, or when that shelf is not in the receiving position. The shelf assembly also provides a container indicator as a receiving control for maintaining the shelf 300 in the receiving position until a container being transferred from a next higher shelf assembly is completely disposed on the shelf surface.

The invention utilizes fluid-operated control components, which have been found to be particularly desirable for light¬ weight containers and packages. In addition to light-weight applications, the fluid-controlled system may be appropriate for heavy-weight applications, perhaps of 100 pounds or more. A preferred fluid-controlled embodiment of the invention can include double acting fluid cylinders that are controlled to raise and lower t.__. shelves. Air is a preferable fluid, although other gases or liquids such as oil could alternatively be utilized. The lowering of the shelves can be accomplished by suitable connections to a lowering cylinder

or to the lowering side of a double-acting cylinder, or by the exhaust of pressure to a raising cylinder.

The shelves, support structure and containers are represented schematically and in phantom in Figs. 9-12, it being understood that the details of these components can be constructed according to known engineering principles. The array of valves and air lines in the control system of the preferred pneumatic embodiment is illustrated schematically to more clearly show the operation of the fluid-operated control system relative to the operation of the shelves. The various valves can be mounted to the support structure and shelves in any fashion that is suitable to permit actuation according to the position of the shelves and the associated containers in the manner to be described. The valves are depicted in conventional pneumatic logic symbology, with adjacent boxes schematically representing the alternate operational configurations of the valves. It should be appreciated, however, that alternative logic designs and control configurations can be designed, and the invention is not intended to be limited to that disclosed herein.

The valves can be selected from several conventional pneumatic valve constructions, such as four-way spool valves, and can be actuated by cam rollers, air pilots, return springs, solenoids and other suitable actuators.

The shelf raising means is preferably a pneumatic cylinder, such as the double acting air cylinder 306. The shelf raising means provides for movement of the shelf 300 at least between an upwardly tilted receiving position, as shown

by the shelf assembly 296 in Fig. 11, and a downwardly tilted discharge position, shown by the shelf assembly 294 in Fig. 12. The air cylinder 306 can be attached between the shelf 300 and the support structure by suitable structure such as a strut 305 and a piston arm 307. The air cylinder 306 can include an upper chamber 308 and a lower chamber 310 that are pneumatically connected to a cylinder control valve 312 through lines 314 and 316, respectively. The cylinder control valve 312, which can be a four-way, double air pilot spool valve, can be configured to selectively provide supply pressure to either the upper chamber 308 or to the lower chamber 310, while exhausting the non-supplied chamber.

When placed in the raising configuration, the cylinder control valve 312 ports supply pressure to the lower chamber 310 through the air line 316. Simultaneously, the upper chamber 308 is exhausted through the line 314. The cylinder control valve 312 can alternatively be placed in a lowering configuration, as shown by the shelf assembly 296 in Fig. 10, wherein pressure is provided to the upper chamber 308 through the line 314 and the lower chamber 310 is exhausted through the line 316. The relative rates of pressurization and exhaust of the opposing chambers 308 and 310 can be regulated to insure smooth raising and lowering of each shelf 300.

In the event of an air supply failure, the air pressure in the air cylinder may be discharged, causing raised shelves to lower prematurely. Accordingly, the air cylinder 306 can be equipped with a return spring 318 (Fig. 9) for maintaining the shelf 300 in the raised position in the absence of air pressure.

The positioning of a shelf 300 between the upwardly tilted receiving position and downwardly tilted discharge position, and the movement of the cylinder control valve 312 between the raising configuration and the lowering configuration, are preferably dependent upon two factors. First, an upwardly tilted shelf should remain in that position so long as the shelf does not have a container, so as to be in a position to receive a container. Second, a shelf should remain upwardly tilted or in an intermediate storage position so long as the next lower shelf assembly is not prepared to receive a container. A shelf can be adapted to move to an intermediate storage position if it has a container and the next lower shelf is unprepared to receive a container.

The pneumatic control system is constructed so as to maintain the cylinder control valve 312 in the raising configuration if the shelf 300 is empty, or in the raising configuration or an intermediate storage configuration if the next lower shelf assembly has a container or is not prepared to receive a container. The container indicator structure preferably includes a container indicator valve 326 to detect the presence of a container on each shelf 300. The container indicator valve 326, which is shown in pneumatic logic symbology, can be a four-way spool valve, and includes a first configuration illustrated within the box 325 of shelf assembly 290 in Fig. 9. The box 325 represents the porting of a supply source 330 to a line 322, and the porting of an exhaust outlet 331 to a line 323. A second configuration, illustrated by the box 327, represents the porting of the supply source 330 to

the line 323, and the porting of the exhaust 331 to the line 322.

The valve 326 is operated by an actuator which responds to the presence or absence of a container on the shelf. For example, a mechanical actuator such as a cam roller 328 can be provided, which will be depressed by a container 291 that is transferred onto the shelf 300. When the container 291 is present on the shelf 300, the indicator valve 326 is oriented to the position represented within box 325, in which flow from the supply source 330 is routed as a lowering signal through the air line 322 to the gate 313 of cylinder control valve 312, while the line 323 is exhausted. The cylinder control valve 312 will therefore be moved from the raising configuration shown within box 337 to the lowering configuration shown with box 335. This will port air to the upper chamber 308 of the air cylinder 306 to lower the shelf 300. A return spring 332 can be utilized to position the valve 326 in the second configuration 327 when a container is removed from the shelf 300, as illustrated by the shelf assembly 296 in Fig. 11. In this orientation, the line 322 is exhausted and a raising signal is routed through the line 323 to the gate 315. The cylinder control valve 312 will be placed in the raising configuration to raise the shelf 300. Other valving and control configurations are also possible.

The pneumatic system preferably also includes transfer control structure operatively connecting the shelf assembly with the next lower shelf assembly. The transfer control structure of a shelf assembly, for example of the shelf

assembly 390, applies the condition of the next lower shelf assembly to the positioning of the shelf 300 of the upper shelf assembly 290, so that the shelf assembly 290 will not be lowered to the discharge position unless the next lower shelf assembly 292 is prepared to receive a container.

The transfer control structure most preferably includes a normally open three-way transfer valve 320 for controlling the passage of a lowering signal through the line 322 to the cylinder control valve 312, according to whether the next lower shelf assembly is presently storing a container. In a presently preferred embodiment, the transfer valve 320 in either the open or closed condition is controlled by the configuration of the container indicator valve 326 of the next lower shelf assembly. An air line 329 taken, for example, from the air line 323 can be utilized to apply a transfer signal to the gate 321 when the container indicator valve 326 is in the raising configuration. The presence of the transfer signal at the gate 321 is operable to close the transfer valve 320 to permit the lowering signal of the container indicator valve 326 of the shelf assembly 290 to pass to the cylinder control valve 312, which will effect lowering of the shelf 300 and transfer of the container.

The open condition of the transfer valve 320 occurs when the next lower shelf assembly is unprepared to receive a container, in which case the transfer signal is not generated through the line 329. The open condition of the transfer valve 320 prevents the lowering signal of the container indicator valve 326 from reaching and actuating the cylinder

control valve 312 of the upper shelf assembly. When the next lower shelf assembly has discharged a container and is prepared to a receive another container, the container indicator valve 326 of that shelf assembly changes configuration and a transfer signal is generated through the line 329 to close the transfer stop valve 320 again. This permits the lowering signal to pass through the line 322 to the cylinder control valve 312 to initiate the lowering of the shelf 300 of the upper shelf assembly if that shelf assembly has a container.

The container indicator valve 326 of the next lower shelf assembly can possibly forward a transfer signal to the upper shelf assembly before the next lower shelf assembly is in the fully upright position, ready to receive a container. This can cause mishaps during the container transferring process. The transfer control structure therefore preferably also includes a receiving position indicator valve 334 which prevents the passage of the transfer signal to the transfer valve 320 until the shelf 300 of the next lower shelf assembly is fully disposed in the receiving position. The receiving position indicator valve 334 can be a normally open three-way valve connected to the support structure and equipped with a mechanical actuator 336 or other structure for contacting or otherwise sensing the position of the shelf 300 of the next lower shelf assembly. The mechanical actuator 336 closes the receiving position indicator valve 334 when the shelf 300 of the next lower shelf assembly is fully in the upwardly tilted, container receiving position, and opens the receiving position

indicator valve 334 when the shelf 300 is not fully in the receiving position.

The container indicator valve 326 is preferably positioned on the shelf 300 such that the actuator 328 extends slightly above the support surface of the shelf, to provide for engagement with a container transferred onto the shelf 300. The container indicator valve 326 and actuator 328 can sense when the container is fully received on the shelf 300 by positioning the actuator 328 at the rear of the shelf 300, nearest the pivot point. A container will not contact the actuator 328 to position the container indicator valve 326 in the lowering configuration until the container has been fully received on the shelf 300. The container indicator valve 326 thereby can also serve as a container position indicator for delaying the discharge of a container until a container is fully received on the shelf 300. Alternative sensors, including mechanical and electronic sensors, can be provided to prevent the lowering of a shelf 300 unless the container has been properly received.

Referring to Fig. 13, the double acting air cylinder 306 can extend from the vertical support structure 302, 304 to connect to a cross bar 346 extending outwardly from the shelf 300. A support plate 348 can extend from the vertical support structure 302 to provide intermediate cantilever support to the cross bar 346 between the shelf 300 and the air cylinder 306. Thus, the raising and lowering forces generated by the air cylinder 306 are transferred more efficiently to the shelf 300, and the effects of torque on the cross bar 346 are

minimized.

In operation, the shelves 300 of the pneumatically controlled shelf assemblies 290, 292, 294 and 296 can be filled with containers 291, 293, 295 and 297 in preparation for automatic dispensing (Fig. 9) . The presence of the container 297 on the shelf 300 positions the respective container indicator valve 326 of the shelf assembly 296 to supply a lowering signal to the air line 322. The lowering signal is restricted from advancing to the air cylinder control valve 312 by the dispensing valve 338, which is preferably a normally closed three-way valve. The dispensing valve 338 can operate through a solenoid actuator connected to a remote control, such as a computer 340.

Actuation of the dispensing valve 338, as signified by the curved arrow 341, opens the dispensing valve 338 and permits passage of the lowering signal through the air line 322 to the cylinder control valve 312. The cylinder control valve 312 is reoriented to the lowering position, whereby supply pressure from a supply 344 is ported to the upper chamber 308 of the air cylinder 306 and air pressure is exhausted from the lower chamber 310. As shown in Fig. 10, this will pivot the shelf 300 to the downwardly tilted discharge position. The container 297 slides off of the shelf 300, and is dispensed from the apparatus.

When the container 297 leaves the shelf 300, the actuator 328 for the container indicator valve 326 is released, permitting the return spring 332 to orient the container indicator valve 326 in the raising configuration, as

illustrated in Fig. 11. This configuration of the indicator valve 326 applies pressure from the supply source 330 to the air line 323 and the gate 315, which causes the cylinder control valve 312 to move to the raising configuration. The raising configuration of the cylinder control valve 312 ports supply pressure to the lower chamber 310 of the air cylinder

306 while exhausting pressure from the upper chamber 308, thereby causing the air cylinder 306 to raise the cylinder arm

307 and the shelf 300 to the upwardly tilted receiving position shown in Fig. 11.

The container indicator valve 326, when in the raising configuration, also supplies a transfer request signal through the air line 329 to the receiving position indicator valve 334 of the shelf assembly 296. The pivoting of the shelf assembly 296 to the fully upwardly tilted receiving position causes suitable contact by the shelf 300 with the actuator 336, which opens the receiving position indicator valve 334 to permit passage of the transfer signal to the gate 321 to open the transfer valve 320 of the next higher shelf assembly, here the shelf assembly 294.

The opening of the transfer valve 320 permits passage of a lowering signal from the container indicator valve 326 of the next higher shelf assembly 294 to the gate 313 of the respective air cylinder control valve 312. This will result in lowering of the shelf 300 of the shelf assembly 294 to the downwardly tilted discharge position (Fig. 12) . Should the shelf assembly 294 not have a container, the container indicator valve 326 would be oriented to the raising

configuration and a signal would be present in the air line 323. The opening of the transfer valve 320 would then be ineffective to lower the shelf 300 until a container is transferred to the shelf assembly 294 to change the configuration of the container indicator valve 326.

When a container leaves the shelf 300 of the shelf assembly 294, the container indicator valve 326 is returned to the raising configuration, thereby signalling the cylinder control valve 312 through the air line 323 to raise the air cylinder 306. A transfer signal is also transferred through the line 329 to the next higher shelf assembly 292, which signal is applied to the gate 321 of the transfer valve 320, to permit the transfer of a lowering signal through the air line 322. This will lower the shelf 300 of the shelf assembly 292, discharging the associated container to the shelf assembly 294. The transfer process described for the shelf assemblies 294 and 296 proceeds up the tower from side to side until all containers have moved to the lower most shelves. Activation of the dispensing valve 338 starts the process again.

The present invention provides storing and dispensing stacks that operate with pivoting shelves, through any number of intermediate positions, when transfer control structure and receiving control structure are used to control, either passively or actively, raising and lowering of shelves. Specific and alternative structure for accomplishing this system of container storage and distribution, in addition to the preferred embodiments set forth above, will be apparent to

those skilled in the art. Although particular details of preferred embodiments have been set forth, the scope of the invention is not limited to the details of these preferred embodiments, but rather, only by a reasonable interpretation of the appended claims.