Field

This application is directed to a rolling finger follower (RFF) with variations on outer arm and pivot body designs to accommodate alternate assembly approaches.

Background

[001] Valvetrains have tight packaging constraints. It is desired to pack the components as efficiently as possible. Prior art configurations have limited lost motion configurations, large footprints, or could otherwise interfere with adjacent components. Prior art configurations also have high cost for material use.

SUMMARY

[002] As disclosed herein, a rolling finger follower (RFF) can comprise variations on outer arm and pivot body designs to accommodate alternate assembly approaches. These approaches help avoid interference with adjacent cylinder head components while obtaining high lost motion. The disclosed rolling finger followers compactly fit on the cylinder head. Also, cost savings can be achieved by mixing materials used. For example, a high durability material can be used for forming the pivot location as part of a drop-in pivot body. Then, a material conducive to stamping can be used for the outer or inner arm assemblies. A retention clip can be devised to secure the pivot body, whether or not it comprises a latch pin. The retention clip can optionally also include a guiding shape that mates to the pivot location of the related valvetrain. Additional features can ensure alignment of the latch pin, when used. Additional features can ensure connections between the drop-in pivot body and the outer arm assembly.

[003] A switching roller finger follower can include: an outer arm assembly comprising a valve end and a pivot end; an inner arm assembly configured to pivot relative to the outer arm assembly, the inner arm assembly comprising a latch; a pivot body mounted to the pivot end of the outer arm assembly, the pivot body comprising a latch pin bore and an inner stake bore; a latch pin mounted in the latch pin bore, the latch pin comprising a guide groove and a contact surface, the guide groove comprising a first lift zone and a second lift zone; and a stake through the inner stake bore, the stake configured to align through the guide groove.

[004] A switching roller finger follower can include: a latch pin configured to reciprocate in the latch pin bore between a latched position where a stake is configured to enter a first lift zone and a latch is configured to engage with a contact surface, and an unlatched position where the stake is configured to enter a second lift zone and the latch is not configured to engage with the contact surface.

[005] A switching roller finger follower can include: an outer arm assembly comprising two outer axle bores, an inner arm assembly comprising an inner axle bore, a roller axle mounted in the inner axle bore, and a thru-axle arranged within the roller axle and through the two outer axle bores.

[006] A switching roller finger follower can include: a pivot body configured for drop-in assembly into a top of an outer arm assembly.

[007] A switching roller finger follower can include: a pivot body comprising at least one tab, and wherein an outer arm assembly further comprises at least one vertical slot for receiving the at least one tab.

[008] A switching roller finger follower can include: a pivot body comprising at least one tab, and wherein an outer arm assembly further comprises at least one top draft integrated with at least one vertical slot, and the vertical slot is configured to receive the at least one tab.

[009] A switching roller finger follower can include: a pivot body configured for drop-in assembly into a rear of an outer arm assembly.

[010] A switching roller finger follower can include: a pivot body comprising at least one tab, and wherein an outer arm assembly further comprises at least one horizontal slot for receiving the at least one tab.

[011] A switching roller finger follower can include: an outer arm assembly comprising at least one top draft, and wherein a pivot body further comprises at least one top draft receiver for receiving the at least one top draft.

[012] A switching roller finger follower can include: a pivot body manufactured by cold forming and an outer arm assembly manufactured by stamping. [013] A switching roller finger follower can include: an outer arm assembly comprising a first outer arm and a second outer arm each comprising an inner surface and an outer surface, wherein each outer surface comprises a recess and wherein each inner surface comprises a protrusion.

[014] A switching roller finger follower can include: an inner surface configured to abut a pivot body.

[015] A switching roller finger follower can include: a retention clip and recesses, wherein the retention clip comprises respective retention prongs configured to seat in the recesses.

[016] A switching roller finger follower can include: a retention clip and at least one tab, wherein the retention clip comprises at least one bent arm configured to abut the at least one tab.

[017] A switching roller finger follower can include: a retention clip, wherein the retention clip comprises a guide hole, retention prongs, and bent arms.

[018] A rolling finger follower can include an outer arm assembly comprising a valve end and a pivot end, the pivot end comprising outer arm slots and a connecting portion; an inner arm assembly configured to pivot relative to the outer arm assembly; and a pivot body comprising pivot body tabs seated in the outer arm slots, the pivot body mounted to the connecting portion.

[019] Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[020] Figures 1A-1 D are views of a roller finger follower.

[021 ] Figures 2A-2D are views of an alternative roller finger follower.

[022] Figures 3A-3C are views of alternative outer arm assemblies and latch pin bodies for use with roller finger followers.

[023] Figures 4A-4C are views of alternative outer arm assemblies and latch pin bodies for use with roller finger followers. [024] Figure 5 is a view of a portion of an alternative outer arm assembly for use with roller finger followers.

[025] Figures 6 is a view of a portion of an alternative outer arm assembly and pivot body for use with roller finger followers.

DETAILED DESCRIPTION

[026] Reference will now be made in detail to the examples which are illustrated in the accompanying drawings. Directional references are for ease of reference to the figures. Commercial implementations can comprise other relative implementations such as north-south, mirror-image, etc.

[027] A rolling finger follower (“RFF”) can form a valve actuation device in a type II end pivot valvetrain. A roller or slider pad can be actuated by an overhead cam actuator while a pivot end pivots on the cylinder head and a valve end transfers the rolling cam lobe actuation to a valve end. As an option, the type II valvetrain can comprise a switching feature such as switching roller finger follower (“SRFF”) 1. SRFF 1 can be configured to provide lost motion for variable valve actuation (“VVA”) including, for example, a first valve lift mode and a lost motion lift mode, though many VVA options can be implemented. Early or late valve opening or closing, engine braking, cylinder deactivation, internal exhaust gas recirculation among many other options can be achieved using one or more SRFF 1 in a valvetrain.

[028] As shown in figure 1 A-1 D, a working example of an SRFF 1 comprises inner arm assembly 101 , outer arm assembly 102, pivot body 103, latch pin 104, and includes a pivot end 107 and a valve end 108. The configuration of the SRFF 1 can be substituted for numerous alternatives known in the art while being compatible with the teachings herein. For example, the outer arm assembly 102 can be with or without outer rollers or slider pads. As another example, the valve end 108, 208 can have an insert instead of a valve pad. As yet another example, the thru-axle 163, 263 can be omitted. The lost motion spring 161 , 261 can be configured in another way.

[029] Inner arm assembly 101 seats within outer arm 102 and comprises an inner pivot axle bore 110, an inner axle bore 111 , an inner roller assembly 112, and latch 113. [030] Outer arm assembly 102 can be cold formed or manufactured from a single stamped piece of material and can comprise a first outer arm 120 and a second outer arm 121 , and at least one connecting portion 122 linking first outer arm 120 with second outer arm 121. Each first outer arm 120 and second outer arm 121 comprise an outer pivot axle bore 123, 124, an outer axle bore 125, 126, an outer roller 127, 128, an optional outer stake bore 129, 130, a block pallet 131 , a top draft 133, and an outer arm slot 135, 136. The at least one connecting portion 122 can form one or more portion of the block pallet 131 for seating the pivot body 103. One or more recess 182 can comprise a stepped portion that can receive a retention clip 137. As an option, retention clip 137 can be seated in the recess 182 or can be seated in the outer arm slot 135, 136. An additional option can comprise bent arms 191 extending from the retention clip 137 and into the outer arm slots 135, 136 to press against the pivot body 103. Retention prongs 189 can catch against the recess 182.

[031] Optionally, outer surfaces 180, 181 of first outer arm 120 and second outer arm 121 can include recess 182 and a mirror recess on second outer arm 121 to facilitate retention of other portions of SRFF 1 . For example, the bent arms 191 and retention prongs 189 of the retention clip 137 can recede into the SRFF 1 to keep a small footprint for the retention clip 137. Conversely and optionally, inner surfaces 184, 185 of first outer arm 120 and second outer arm 121 can include protrusion 186 and a mirror protrusion on first outer arm 120 to facilitate retention of other portions of SRFF 2. For example, the pivot body 103 can be wedged, guided, press-fit, or clamped in place by the inner surfaces 184, 185.

[032] Pivot body 103 seats in the pivot end 107 of outer arm assembly 102. Pivot body 103 can optionally be secured by top draft 133 and a mirror top draft on second outer arm 121 . Pivot body 103 can comprise one or more of a latch pin bore 141 , an optional inner stake bore 142, a socket 143, top draft receivers 144, 145, and block seat 148. Connecting portion 122 of outer arm assembly 102 can form block pallet 131 that can surround or seat one or more portions of block seat 148 of the pivot body 103. Options for seating the pivot body 103 in the pivot end 107 can comprise a press- fit, crush-fit, slip-fit, weld, among others. Optional protrusions, such as protrusion 186 and a mirror protrusion on first outer arm 120, in outer arm assembly 102 can also optionally facilitate the retention of pivot body 103.

[033] Latch pin 104 seats within, and slides within, latch pin bore 141 of pivot body 103. Optional features of the latch pin 104 comprise a contact surface 150, a guide groove 151 , a biasing retainer 152, and an actuation surface 153. A bleed passage 156 can optionally be included through the latch pin 104 to transfer lubrication, actuation, or other fluid from the socket 143 to the bleed port 149. Biasing retainer 152 secures biasing mechanism 154 which is sleeved along latch pin 104. Biasing mechanism 154 is seated between biasing retainer 152 and pivot body 103. The biasing mechanism 154 is illustrated to bias the latch pin 104 to an unlatched position, but an opposite bias can be achieved using an alternative known in the art for biasing the latch pin 104 to a latched position. The latch pin 104 can be configured to reciprocate in the latch pin bore 141 between a latched position where the stake 155 is configured to enter the first lift zone 193 and the latch 113 is configured to engage with the contact surface 150, and an unlatched position where the stake 155 is configured to enter the second lift zone 194 and the latch 113 is not configured to engage with the contact surface 150. In the unlatched position, the latch 113 can swing past the contact surface 150. Or, using a stepped latch pin as known in the art, multiple contact surfaces can be switched among.

[034] Optional stake 155 passes through optional outer stake bores 129, 130 of outer assembly 102, optional inner stake bore 142 of pivot body 103, as well as guide groove 151 of latch pin 104. Optional stake 155 can optionally be used to further secure pivot body 103 to outer body assembly 102 and can optionally serve as a travel limit for latch pin 104 within the confines of guide groove 151 . However, in lieu of optional stake 155 and associated stake bores 129, 130, 142, pivot body 103 can be welded or crush- coupled to outer arm assembly 102.

[035] Pivot axle 160 passes through outer arm assembly 102 via outer pivot axle bores 123, 124, through inner arm assembly 101 via inner pivot axle bore 110, and lost motion spring 161. Pivot axle 160 is one example for providing relative motion between an inner arm assembly 101 and an outer arm assembly 102. Other alternatives known in the art are compatible herewith, such as sliding or reciprocating inner arm assemblies.

[036] Hollow roller axle 162 is received by inner axle bore 111. Inner roller can roll on roller axle 162 with or without needle roller bearings. Outer axle bores can be formed similarly to outer axle bores 325, 425 so that inner roller assembly 112 and outer rollers 127, 128 can be associated with thru-axle 163. Thru-axle 163 passes through roller axle 162, and roller axle 162 can form a travel limit for thru-axle 163. The range of travel of thru-axle 163 within roller axle 162 is defined by gap G1 , and serves as a boundary of the magnitude of lost motion which can be absorbed by SRFF 1. Many alternative lost motion configurations exist in the art and are compatible with the pivot body and outer arm teachings herein.

[037] In one embodiment, SRFF 1 can comprise an outer arm assembly 101 comprising a valve end 108 and a pivot end 107; an inner arm assembly 101 configured to pivot relative to outer arm assembly 101 , the inner arm assembly 101 comprising a latch 113; a pivot body 103 mounted to the pivot end 107 of the outer arm assembly 101 , the pivot body 103 comprising a latch pin bore 141 and an inner stake bore 142; a latch pin 104 mounted in the latch pin bore 141 , the latch pin 104 comprising a guide groove 151 and a contact surface 150, the guide groove 151 comprising a first lift zone 193 and a second lift zone 194; and a stake 155 through the inner stake bore 142, the stake 155 configured to align through the guide groove 151.

[038] In another embodiment, latch pin 104 can be configured to reciprocate in the latch pin bore 141 between a latch position where stake 155 is configured to enter the first lift zone 193 and the latch 113 is configured to engage with the contact surface 150, and an unlatched position where the stake 155 is configured to enter the second lift zone 194 and the latch 113 is not configured to engage with the contact surface 150.

[039] In another embodiment, outer arm assembly 102 can comprise two outer axle bores 125, 126, inner arm assembly 101 can comprise inner axle bore 111 , roller axle 162 is mounted in inner axle bore 111 , and thru-axle 163 is arranged within roller axle 162 and through the two outer axle bores 125, 126.

[040] As shown in FIG. 2A, SRFF 2 comprises inner arm assembly 201 , outer arm assembly 202, pivot body 203, latch pin 204, and includes a pivot end 207 and a valve end 208. While Figures 1A-1 D & 3A-5 provide a pivot body 103, 303, 403 that is configured for drop-in assembly into a top of the outer arm assembly 102, 302, 402, Figures 2A-2D & 6 provide the pivot body 203, 603 configured for drop-in assembly into a rear of the outer arm assembly 202, 602. The switching roller finger follower 2 comprises a pivot body 203 further comprising at least one tab (pivot body tab 246, 247), and the outer arm assembly 202 further comprises at least one horizontal slot (outer arm slot 235) for receiving the at least one tab.

[041] In Figures 3C and 4C, the switching roller finger follower 3, 4 is configured for drop-in assembly of the pivot body 303, 403 into a top of the outer arm assembly 302, 402. Pivot body 303, 403 comprises at least one tab, also called pivot body tab 348, 448. The outer arm assembly 302, 402 comprises at least one vertical slot, also called outer arm slot 335, 433, for receiving the at least one tab. In Figures 4A-4C, the outer arm assembly is configured to comprise at least one top draft with integrated slots 433 or 434. The vertical slot portion of 433 or 434 is configured to receive the at least one tab (pivot body tab 447 or 448) while the top draft portion of 433 or 434 is configured to mate with the pivot body 403, which further comprises at least one top draft receiver 444 for receiving the at least one top draft 433 or 434.

[042] In this working example, inner arm assembly 201 seats within outer arm assembly 202 and comprises an inner pivot axle bore 210, an inner axle bore 211 , an inner roller assembly 212, and latch 213.

[043] Outer arm assembly 202 can be cold formed or manufactured from a single stamped piece of material and can comprise a first outer arm 220 and a second outer arm 221 , and at least one connecting portion 222 linking first outer arm 220 with second outer arm 221 . Each first outer arm 220 and second outer arm 221 comprise an outer pivot axle bore 223, 224, an outer axle bore 225, 226, an outer roller 227, 228, an optional outer stake bore 229, 230, a block pallet 231 , a top draft 233, 234, and an outer arm slot 235, 236 for receiving an optional retention clip 237 as well as pivot body tabs 246, 247.

[044] Optionally, outer surfaces 280, 281 of first outer arm 220 and second outer arm 221 can be stamped or otherwise formed to include recess 282 and a mirror recess on outer arm 221 to facilitate retention of other portions of SRFF 2. Similarly and conversely, inner surfaces 284, 285 of first outer arm 220 and second outer arm 221 can be stamped or otherwise formed to include protrusion 286 and a mirror protrusion on inner surface 285 to facilitate retention of other portions of SRFF 2.

[045] Therefore, outer arm assembly 202 can comprise a first outer arm 220 and a second outer arm 221 , each comprising an inner surface 284, 285 and an outer surface 280, 281 , wherein each outer surface 280, 281 can comprise a recess 282 and a mirror recess on outer surface 281 , and each inner surface 284, 285 can comprise a protrusion 286 and a mirror protrusion on inner surface 285.

[046] As shown in Figure 2B, pivot body 203 seats from above in the pivot end 207 of outer arm assembly 202, secured by top drafts 233, 234, and comprises a latch pin bore 241 , an optional inner stake bore 242, a socket 243, top draft receiver 244 and a mirror top draft receiver on the opposite side of pivot body 203, pivot body tabs 246, 247, and block seat 248. Inner surface 284, 285 can be configured to abut pivot body 203. Optional protrusions 286 and a mirror protrusion on inner surface 285 in outer arm assembly 202 can also facilitate the retention of pivot body 203 within outer arm assembly 202 as shown in figures 3C and 4C. Connecting portion 222 of outer arm assembly 202 can form block pallet 231 that can surround or seat one or more portions of block seat 248 of the pivot body 203. Optional protrusions 286 and a mirror protrusion on inner surface 285 in outer arm assembly 202 can also facilitate the retention of pivot body 203. Note that, optionally, block seat 248 can be reduced such that pivot body 203 has a smaller footprint compared to pivot body 103. The reduced footprint of SRFF to reduce the size of pivot body 203 or otherwise allow SRFF 2 to be deployed in confined areas.

[047] Retention clip 237 can comprise a guide hole 288, retention prongs 289, 290, and bent arms 291 , 292. Retention clip 237 provides circular guide hole 288 to direct a ball end of a hydraulic lash adjuster or other pivot device into socket 243 of pivot body 203. Retention clip 237 can be stamped to form retention prongs 289, 290. Retention prongs 289, 290 can seat in recess 282 and a mirror recess on outer arm 221 while bent arms 291 , 292 can engage with outer arm slots 235, 236. When bent arms 291 , 292 are applied to outer arm slots 235, 236, bent arms 291 , 292 can press on pivot body 203 to bias pivot body 203 into position as shown in figure 2D. While figure 2B shows outer arm slots 235, 236 as a pass-through gap in first outer arm 220 and second outer arm 221 , outer arm slots 235, 236 can also manifest as a recess in first outer arm 220 and second outer arm 221 as seen in figure 2C.

[048] Alternatively, retention clip 237 can be configured to comprise only retention prongs 289, 290. As noted above, retention prongs 289, 290 can be configured to seat in recess 282 and a mirror recess in outer arm 221 . In another alternative, retention clip 237 can comprise at least one bent arm 291 or 292 configured to abut at least one pivot body tab 246 or 247.

[049] Latch pin 204 seats within, and slides within, latch pin bore 241 of pivot body 203. Optional features of the latch pin 204 comprise a contact surface 250, a guide groove 251 , a biasing retainer 252, and an actuation surface 253. A bleed passage 256 can optionally be included through the latch pin 204 to transfer lubrication, actuation, or other fluid from the socket 243 to the bleed port 249. Biasing retainer 252 secures biasing mechanism 254 which is sleeved along latch pin 204. Biasing mechanism 254 is seated between biasing retainer 252 and pivot body 203. The biasing mechanism 254 is illustrated to bias the latch pin 204 to an unlatched position, but an opposite bias can be achieved using an alternative known in the art for biasing the latch pin 204 to a latched position. The latch pin 204 can be configured to reciprocate in the latch pin bore 241 between a latched position where the stake 255 is configured to enter the first lift zone 293 and the latch 213 is configured to engage with the contact surface 250, and an unlatched position where the stake 255 is configured to enter the second lift zone 294 and the latch 213 is not configured to engage with the contact surface 250. In the unlatched position, the latch 213 can swing past the contact surface 250. Or, using a stepped latch pin as known in the art, multiple contact surfaces can be switched among.

[050] Optional stake 255 can pass through optional outer stake bores 229, 230 of outer assembly 202, optional inner stake bore 242 of pivot body 203, as well as guide groove 251 of latch pin 204. Top draft 233, 234 can be configured to hold pivot body 203 against block pallet 231 , while optional stake 255 prevents pivot body 203 from rocking on the block pallet 231 as latch pin 204 reciprocates. Further, optional stake 255 can serve as a travel limit for latch pin 204 within the dimensions of guide groove 251 . However, in lieu of - or in addition to - optional stake 255 and associated stake bores 229, 230, 242, pivot body 203 can be welded or crush-coupled to outer arm assembly 202. As seen in figure 2C, top drafts 233, 234 and top draft receiver 244 and a mirror top draft receiver on the opposite side of pivot body 203 can be eliminated to streamline manufacturing, and pivot body 203 can be secured by welding, crush-coupling, or by interfacing with protrusion 286 and a mirror protrusion on inner surface 285.

[051] Pivot axle 260 passes through outer arm assembly 202 via outer pivot axle bores 223, 224, through inner arm assembly 201 via inner pivot axle bore 210, and lost motion spring 261.

[052] Hollow roller axle 262 is received by inner axle bore 211 as well as outer axle bores 225, 226, inner roller assembly 212, and outer rollers 227, 228. Thru-axle 263 passes through roller axle 262, and roller axle 262 can form a travel limit for thru- axle 263. Inner arm assembly 201 pivots on pivot axle 260 and compresses lost motion spring 261 when a cam lobe presses on the inner roller assembly 212. The travel of the roller in inner roller assembly 202 is limited by the engagement of the thru-axle 263 against roller axle 262. The range of travel of thru-axle 263 within roller axle 262 is defined by gap G2. Note that the greater diameters of roller axle 262 and outer axle bore 225, 226, as compared to roller axle 162 and outer axle bore 125, 126 of figure 1 , allow gap G2 to be greater than gap G1 , yielding a greater possible amount of lost motion which can be absorbed by SRFF 2, though the magnitudes of either G1 or G2 are a matter of design choice to balance lift heights.

[053] An actuation assembly 270 can be controlled to switch between a first valve lift mode and a second valve lift mode. Actuation assembly 270 can actuate latch pin 204 of SRFF 2 by exerting or releasing force on actuation surface 253 of latch pin 204. When actuation assembly 270 engages with actuation surface 253, latch pin 204 can be configured to slide along latch pin bore 241 and guide groove 251 to engage contact surface 250 against latch 213 on inner arm assembly 201 . When actuation assembly 270 disengages with actuation surface 253, biasing mechanism 254 pushes against biasing retainer 252 of latch pin 204, sliding latch pin 204 along the longitudinal axes of latch pin bore 241 and guide groove 251 such that contact surface 250 is not engaged against latch 213 on inner arm assembly 201 . As mentioned above, the latch pin 204 can be configured in alternatives, such as having the actuation assembly 270 push or pull on the latch pin 204.

[054] Placing stake 255 in the guide groove 251 can prevent the latch pin 204 from rotating in the latch pin bore 241 . Stake 255 can also serve as a travel limit with the guide groove 251 to facilitate the desired VVA. First lift zone 293 can be realized by latch pin 204 in a first location, and a second lift zone 294 can be realized by latch pin 204 in a second location. The number of lift zones can be varied to correspond with additional locations for latch pin 204 by modifying latch pin 213, contact surface 250, and guide groove 251. Contact surface 250 can serve as a latching shelf for latch 213 locking the inner arm assembly 101. By moving the latch pin 204, a corresponding valve lift height can be conveyed by a cam lobe pushing on inner roller assembly 212 and in a first lift zone 293 wherein latch pin 204 is located to allow latch 213 to engage with contact surface 250, or, in a second lift position 281 wherein latch pin 204 is located so latch 213 is disengaged from contact surface 250, a cam lobe can push the inner roller assembly 212 down in lost motion, either partial or full lost motion, and the cam lobe can ride on outer rollers 127, 128.

[055] Inner roller assembly 212 can be engaged by a cam lobe to accomplish a first valve lift. However, the lost motion lift mode can result in zero valve lift or a valve lift that is less than the first valve lift. VVL such as cylinder deactivation (“CDA”), engine braking (“EB”), late intake valve closing (“LIVC”), early exhaust valve opening (“EEVO”), among many other options can be implemented. The lift height can be varied for the valvetrain application.

[056] Figure 2A shows latch 213 unlatched from contact surface 250. A travel limit can be formed via thru-axle 263 being restricted by roller axle 262. Numerous travel limit alternatives exist in the art, such as steps or other engaging surfaces between the inner arm assembly 201 and the outer arm assembly 202. Or, thru-axle 263 can pass through travel bores in the outer arm assembly 202. Also, many aspects are compatible with cantilever post alternatives. So, first and second outer rollers 227, 228 can be integrated onto the thru-axle 263 for travel therewith. Fasteners such as bushings or the like, can secure the first and second outer rollers 227, 228 to the thru- axle 263. Or, first and second outer rollers 227, 228 can be mounted on cantilevered posts of the first and second outer arms 220, 221 , among options. Also, one or more of the inner roller assemblies 212 and first and second outer rollers 227, 228 can be exchanged for slider pads.

[057] As shown in Figure 2B, SRFF 2 allows alternate assembly of the pivot body from the rear of outer arm assembly 202 via outer arm slots 235, 236 to the pivot body tabs 246, 247, as opposed to the top of outer arm assembly 202 as in SRFF 1 . This rear-assembly allows installation of SRFF 2 into tight confines which could otherwise prevent the use of an SRFF with a top-down assembly as seen in SRFF 1 . Further, as shown in Figure 2C, the top draft can be eliminated from the outer arm as well as the top draft receiver from the pivot body, which saves machining time and costs.

[058] Further variations can be made to the outer arm assemblies and latch pin bodies. As shown in Figure 3A, an SRFF can comprise an outer arm assembly 302, a pivot body 303, and a latch pin 304. Outer arm assembly 302 can comprise first outer arm 320, second outer arm 321 , connecting portion 322, compact top drafts 333, 334, outer arm slots 335, 336, outer pivot axle bore 323, outer axle bore 325, outer stake bores 329, 330, inner surfaces 384, 385 with protrusion 386, outer surfaces 380, 381 with recess 382, and retention clip receivers 387, 388. Pivot body 303 can comprise pivot body tab 347, 348, optional inner stake bore 342, top draft receivers 344, 345, and latch pin bore 341.

[059] Pivot body 303 can be assembled from the top of outer arm assembly 302 as partially seen in SRFF 3 of Figure 3C, with pivot body tabs 347, 348 pairing with outer arm slots 335, 336 of outer arm assembly 302 and compact top drafts 333, 334 of outer arm assembly locking into top draft receivers 344, 345. The reduced length of compact top drafts 333, 334 allows additional room on pivot body 303 and outer arm assembly 302 for pivot body tab 347, 348 and outer arm slots 335, 336. Optional stake 355 seated in outer stake bores 329, 330 and inner stake bore 342 can assist in securing pivot body 303.

[060] Note that pivot body 303 has a further reduced footprint compared to pivot body 103 and pivot body 203 as seen in Figure 1 and Figure 2. The reduced foot print of pivot body 303, in turn, reduces the size of the SRFF and can allow it to be utilized in confined environments where SRFF 1 or SRFF 2 might be too large or otherwise unsuitable.

[061] Figures 4A-C show another variation to the outer arm assembly and pivot body which are incorporated in SRFF 4, as partially shown in FIG 4C. An SRFF can comprise an outer arm assembly 402, a pivot body 403, and latch pin 404. Outer arm assembly 402 comprises first outer arm 420, second outer arm 421 , connecting portion 422, top drafts with integrated slots 433, 434, retention clip receivers 435, 436, outer stake bores 429, 430, outer pivot axle bore 423, and outer axle bore 425.

[062] Pivot body 403 comprises draft receivers with integrated tabs 447, 448, latch pin bore 441 , optional stake bore 442. Top drafts with integrated slots 433, 434 can then interlock with draft receivers with integrated tabs 447, 448 to secure pivot body 403 to outer arm assembly 402. Stake 455 can be seated in inner stake bore 442 and outer stake bores 429, 430. Further, pivot body 403 can be manufactured by cold forming to be laterally symmetric about axis AA, thereby reducing manufacturing time and costs. Furthermore, different manufacturing techniques can be employed, such as pivot body 303, 403 being manufactured by cold forming while the outer arm assembly 302, 402 is manufactured by stamping.

[063] So, the drop-in assembly of the various pivot bodies 103, 203, 303, 403, 603 into their respective outer arm assemblies 102, 202, 302, 402, 502, 602 allows combinations of different cost and durability materials, as a design choice. The retention clip 137, 237 also yields light weighting and further material selection options, as by offering up guide hole 288 as an augment to socket 243. And, when used as a source of bias or pressure on the pivot body, the retention clip 137, 237 can optionally eliminate a welding step. The retention clip 137, 237 can be used with or without the illustrated alternative top drafts 334, 433 and top draft receivers 344, 444. So, the teachings of the various embodiments are usable together.

[064] Figures 5 and 6 show alternative outer arm assemblies and latch pin bodies. Figure 5 shows a portion of an alternative outer arm for use with an outer arm assembly. Outer arm 520 comprises an outer arm slot 521 for receiving a latch pin assembly from above, optional outer stake bore 522 for receiving an optional stake bore, as well as outer recess 523. Recess 523 can receive an optional retention clip. Outer arm slot 521 can provide vertical and lateral support, and act as a stopping feature, for a pivot body. Outer arm slot 521 can also prevent a pivot body from rocking while a latch pin reciprocates. Outer arm 520 can be coupled with a mirror-image version via a connecting portion to form an outer arm assembly.

[065] Figure 6 shows an alternative outer arm assembly 602 and pivot body 603 in a partially view of an RFF 6. RFF 6 can comprise an outer arm assembly 602 and a pivot body 603.

[066] Outer arm assembly 602 can be a single stamped piece of material and can comprise a first outer arm 620 and a second outer arm 621 , and at least one connecting portion 622 linking first outer arm 620 with second outer arm 621 . Each first outer arm 620 and second outer arm 621 can comprise an outer axle bore 626, an optional outer stake bore 629, 630, a recess 632 on the outer surface, a protrusion 633 on the inner surface, and an outer arm slot 635, 636 for receiving a retention clip and/or pivot body 603.

[067] Pivot body 603 comprises pivot body tabs 640, 641 , inner stake bore 642, as well as a socket, similar to sockets 143, 243 discussed above. Pivot body tabs 640, 641 are retained by outer arm slot 635, 636 and, with optional protrusion 633, assist in seating and positioning pivot body 630 within outer arm assembly 602. As compatible options, pivot body tabs 640, 641 can press-fit, crush-fit, or welded into the outer arm slots 635, 636, or pivot body tabs 640, 641 can be biased in place as taught above for retention clip 237.

[068] One embodiment of RFF 6 can comprise an outer arm assembly 602 comprising a valve end, similar to valve ends discussed above, and a pivot end 607, the pivot end comprising outer arm slots 635, 636 and a connecting portion 622; an inner arm assembly, similar to inner arm assemblies discussed above, configured to pivot relative to the outer arm assembly 602; and a pivot body 603 comprising pivot body tabs 640, 641 seated in the outer arm slots 635, 636, the pivot body 603 mounted to the connecting portion 622.

[069] Other implementations will be apparent to those skilled in the art from consideration of the specification and practice of the examples disclosed herein.