Patent GB-763943-A (GB)
Title: Improvements in or relating to conveyor systems
Inventor: BURROWS ARTHUR THOMAS CHARLES
IPC: B65G17/26
Filed: 1953-06-19
Abstract: 763,943. Endless conveyers. KING, Ltd., G. W. June 18, 1954 [June 19, 1953], No. 16946/53. Class 78 (1). Load carriers supported on one endless driven chain are transferred to another endless driven chain running parallel with the first chain by a transfer unit comprising a piston and cylinder unit mounted in such a way that supply of pressure fluid to either side of the piston causes an initial vertical movement followed by a rotary movement, a transfer arm being attached to the cylinder, and the arrangement being such that supply of fluid to one side of the piston engages the arm with a load carrier on the first chain and transfers it to the second chain, and supply of fluid to the opposite side of the piston disengages the arm and returns it to its initial position. As shown, each load carrier 5 is provided with a shoe 7 resting on the support rollers of a chain 1, the load carriers and the chain being constructed as described in Specifications 701,610 and 719,888. Chain 1 runs in a guide 2 the upper part of which acts as a guard to prevent the shoes from leaving the track. A similar chain 3, running in a guide 4, is disposed with a portion parallel and adjacent to a portion of chain 1. A selector key 87 is also secured to each carrier and operates as described in Specification 763,944 to select one of several transfer stations such as that shown. Each transfer station comprises a transfer cylinder 9 which is rotatably mounted in a frame 10 by a shaft 30, secured to its upper end and slidably engaging within a bearing 29 so that limited vertical movement is allowed, and a lower bearing member 13. The piston 8 is connected by a rod 11 to a screw 12 engaged in a nut formed by the member 13, while relative rotation between the piston and cylinder is prevented by a cross bar 14 on the screw-engaging slots 15 in an extension 16 of the cylinder wall. The cylinder is caused to have an initial vertical movement to the extent allowed by abutment of the top of the cylinder or a collar 32 against the bearing 29 by the provision of a brake band 20 frictionally engaged around it, a lug 21 attached to the brake band engaging between fixed lugs 21 and 22. When a carrier reaches the selected station it causes movement of a sliding plate which releases a spring-loaded plunger to operate a control valve 28, and also engages an arm 26 to rotate a shaft 24 journalled in the transfer arm 17 and hence move a stop arm 23 on the shaft into position to stop the carrier. The arrested carrier raises one end of a stop lever 36, the other end of which is thereby depressed to retain a following load carrier. When valve 28 is operated, fluid is supplied to the lower end of cylinder 9 and simultaneously to two further cylinders, one of which 59 causes a stop arm 54 to be lowered into the path of load carriers on the chain 3 and also lowers an arm 50 whose outer end depresses a hinged section 48 of the inner wall of guide 4 against the pressure of a spring-loaded link 49, while the other (not shown) lowers a similar hinged section of the inner wall of guide 2, so that the load carrier to be transferred is free to leave guide 2 and enter guide 4 at these points. Upon supply of fluid to cylinder 9, the cylinder is first lowered, since the brake band 20 restrains it from rotation, so that arm 17 engages the load carrier, and is then rotated through 180'degrees into engagement with a stop 19 so that arm 17 pushes the load carrier over a rollerway 27 to the other chain. As cylinder 9 reaches the end of its rotary movement an arm (not shown) secured to it engages a lever 84 which through a link 85 restores the valve 28 and its operating plunger to its original position. This exhausts cylinder 59 and the corresponding cylinder (not shown) associated with guide 2, and causes fluid to be supplied to the upper end of cylinder 9 so that the latter first rises, owing to the action of the brake band, and then rotates in the reverse direction to return arm 17 into its initial position. Instead of brake band 20, a pair of opposed spring-loaded pawls may be adapted to co-operate with a projection on the cylinder, so that the pawls prevent rotation until the pro jection is raised or lowered to clear them. Instead of a screw 12 a member having two pairs of helical grooves of opposite hand may be used, the nut being replaced by a pair of pivoted keys adapted to be adjusted to follow one or other pair of grooves. By adjusting the keys at the end of a 180 degree rotation of the cylinder the return movement may be in the same direction to complete a 360 degree rotation. The brake band 20 may also be replaced by a projection on the cylinder 9 adapted to be restrained against rotation at the beginning of the transfer movement until arm 17 is lowered and thereafter to follow below a guide which prevents upward movement of arm 17 until completion of the return movement. If prior to transfer of a load carrier from chain 1 to chain 3 a load carrier on chain 3 which has passed the stop arm 54 is in the transfer region a skid 67 is displaced which operates through a crank 66, elastic connection 65 and link 64 a control adapted to prevent valve 28 from being operated. If, however, during transfer a load carrier arrives at stop arm 54 and displaces skid 67 the elastic connection 65 prevents jamming of the valve gear while ensuring that a further transfer operation is prevented until the load carrier held at stop arm 54 has been allowed to pass the transfer region. In order that only loaded carriers may be transferred when loaded and unloaded carriers are present, a pivoted skid plate 99, Fig. 10, is provided in the track adjacent each transfer station for engagement with the. vertically movable peg provided on each carrier as described in Specification 701,610.. The arrangement is such that only the pegs on unloaded carriers will be in a position to pivot the skid, this movement then being communicated by a sheathed cable to a latch lever (not shown) adapted to lock the sliding plate at the station being passed, to prevent its operating the valve 28 or the stop arm 23.