Trolley drive for over and under conveyor

Claim 2

A power and free conveyor having trolley and power tracks spaced a constant distance from each other throughout the system and a driven propelling member mounted in said power track, at least one elongated load carrier supported on said trolley track for travel therealong, said load carrier having a primary drive post at its leading end and secondary drive post at its trailing end, a primary drive on said propelling member adapted to engage said primary drive post, an auxiliary drive on said propelling member spaced from said primary drive a distance greater than the spacing between said primary and secondary drive posts, the improvement in said conveyor comprising: said auxiliary drive having a pusher arm, said pusher arm having a weighted end and a drive end and means pivotally mounting said pusher arm intermediate said ends to said auxiliary drive, said pusher arm urged by its weighted end into a retracted position disengaged from both said primary and secondary drive posts; actuating means at selected positions along said conveyor for engaging said pusher arm to urge said pusher arm into an extended position and holding said pusher arm in said extended position; said pusher arm, when so extended, being engageable with said secondary drive post for transmitting motion from said propelling member to said load carrier.

Claim 3

A conveyor as described in claim 1 wherein said actuating means includes a rail means positioned adjacent said power track for engaging said weighted end of said pusher arm, said rail means including a ramp portion inclined upwardly for engagement with said weighted end of said pusher arm to urge said pusher arm into said extended position, said rail means including a second portion extending downstream from said ramp portion, said second portion being generally parallel to the direction of movement of said auxiliary drive and engageable with said weighted end to hold said pusher arm in said extended position.

Claim 4

A conveyor as described in claim 2 wherein said actuating means includes a second rail means defining a ramp portion spaced longitudinally from said first rail means, said second ramp portion being inclined downwardly for engagement with said weighted end of said pusher arm to urge said pusher arm into said retracted position to provide positive disengagement by said pusher arm from said secondary drive post.

Claim 5

A conveyor as described in claim 3 wherein said weighted end of said pusher arm includes a laterally projecting pin having a cam roller mounted on the end for engagement with said rail means.

Claim 6

A conveyor as described in claim 1 wherein said conveyor includes inclined track portions to provide relative vertical ascent and descent of said load carrier; said primary drive including a puller arm pivotally mounted thereon and urged by its gravitational weight into an extended drive engaging position, said puller arm including a downwardly opening socket haVing one wall defining a drive dog adjacent its rearward end and a second wall defining a holdback dog adjacent its forward end, said walls being adapted for engagement with said primary drive post, said socket being non-compatible with said secondary drive dog, the upper surface of said socket having a downwardly offset portion adjacent said second wall to limit the distance said puller arm seats down over the primary drive post when the post is in engagement with said second wall; said upper surface having a smooth transition section between its forward and rearward portions for camming said puller arm on said drive post; said forward and rearward portions of said upper surface positioning said puller arm to provide straight-line force generation through said puller arm pivot.

Claim 7

A conveyor as described in claim 5 wherein said conveyor includes additional actuating means at selected positions along said conveyor for engaging said puller arm to urge said puller arm into a retracted non-drive engaging position; and means for preventing disengagement between said puller arm socket and primary drive post during movement of said load carrier along said inclined track portions.

Claim 8

A conveyor as described in claim 6 wherein said additional actuating means includes a rail means positioned adjacent said power track for intercepting a portion of said puller arm, said rail means including a ramp portion inclined upwardly for engagement with said portion of said puller arm to urge said puller arm upwardly into a retracted, non-drive engaging position, said rail means including a second portion extending downstream from said ramp portion, said second portion being generally parallel to the direction of movement of said puller arm and engageable thereby to hold said puller arm in said retracted position, said means for preventing disengagement between said puller arm socket and primary drive post comprising a second rail means similar to said second portion of said rail means spaced slightly above said portion of said puller arm when said puller arm socket is engaged with said primary drive post to prevent disengagement between said puller arm socket and primary drive post.

Claim 9

A conveyor as described in claim 5 wherein said propelling member includes a front and rear longitudinally spaced clevis interconnecting said puller and pusher arms to said power track, each of said clevis members being identical and adapted for receipt of either of said puller or pusher arm.

Claim 10

A conveyor having a power track and a propelling member movable along said power track; a puller arm having a lead end and a trailing end, said puller arm pivotally mounted adjacent its lead end to said propelling member; a load carrier movable along a load track, said carrier having a drive post projecting towards said puller arm, said puller arm at its trailing end having a socket formed therein to capture said drive post, said socket being longer than the fore and aft length of said drive post, said socket defining integral rearward drive and forward holdback faces spaced longitudinally from each other to provide and inhibit respectively movement of said carrier with respect to said puller arm when said drive post is captured in said socket, said socket having an upper surface extending between said drive and holdback faces, said upper surface having forward and rearward portions, the improvement comprising: said forward portion of said upper surface of said socket being downwardly offset adjacent said holdback face to restrict the depth or entry of said drive post into said socket when said holdback face is engaged with said drive post so that the pivot angle of said puller arm relative to said power track is larger when said arm is operable to pull said load carrier than when said puller arm is operable to hold back said load carrier.

Claim 11

A conveyor having a power track and a propelling member movable along said power track; a puller arm having a lead end and a trailing end, said puller arm pivotally mounted adjacent its lead end to said propelling member; a load carrier movable along a load track, said carrier having a drive post projecting towards said puller arm, said puller arm at its trailing end having a socket formed therein to capture said drive post, said socket being longer than the fore and aft length of said drive post, said socket defining integral rearward drive and forward holdback faces spaced longitudinally from each other to provide and inhibit respectively movement of said carrier with respect to said puller arm when said drive post is captured in said socket, said socket having an upper surface extending between said drive and holdback faces, said upper surface having forward and rearward portions, the improvement comprising: said forward portion of said upper surface of said socket being downwardly offset adjacent said holdback face to restrict the depth or entry of said drive post into said socket when said holdback face is engaged with said drive post so that the pivot angle of said puller arm relative to said power track is larger when said arm is operable to pull said load carrier than when said puller arm is operable to hold back said load carrier.

Claim 12

A conveyor as described in claim 9 wherein said upper surface of said socket has a smoothly curved transition section between the forward and rearward portions thereof for camming said puller arm about the top of said drive post as said drive post shifts forwardly or rearwardly within said socket.

Claim 13

A conveyor as described in claim 10 wherein said rearward portion of said upper surface has a fore and aft length at least equal to that of the top of said drive post to permit said forward portion of said upper surface to rest on the top of said drive post when said drive post and said rearward drive faces are engaged.

Claim 14

A conveyor as described in claim 11 wherein a pin provides said pivotal mounting of said puller arm to said propelling member and said pivot angle of said puller arm both when said drive post is engaged with said drive face and when engaged with said holdback face is such that the forces generated about said pin pass through said pin eliminating bending movements about said pin.