Patent GB-653434-A (GB)
Title: Improvements in or relating to conveyor or transmission systems
IPC: B65G17/38
Filed: 1947-06-16
Abstract: 653,434. Chains. CARVELL, E. R. June 16, 1947, No. 15848. [Class 24] [Also in Group XXX] In a transmission system of the type which comprises a flexible member including a series of connected elements and in which selected elements spaced along the length of the member are adapted to be displaced laterally relatively to elements intermediate those selected to reduce the effective length of the member, means are provided for positively displacing the selected elements laterally and for positively maintaining the resulting relative lateral displacement against the action of any centering forces produced by a tension in the member while the elements are passing through a section of their travel in the system. As shown in Fig. 6 the pins 203 of a chain comprising links 201, 202 and rollers 204 are extended upwardly and downwardly and carry rollers 205, 206, 207, 208, alternate upper rollers 205 and alternate lower rollers 208 being longer than the intermediate rollers 206, 207. The rollers 205, 208 engage upper and lower tracks 209, 210 which diverge at 219, 220 to meet parallel sections 221, 226 so that alternate pins 203 of the chain are moved laterally relatively to the intermediate pins as the chain moves to the right in Fig. 6, so decreasing the effective length of the chain. After the pins 203 have diverged, further guides 233, 234 which may however be omitted, together with the pins 206, 207, engage the shorter pins 206. 207. The parallel section of the tracks 221, 226 is terminated in a similar section to that shown in Fig. 6 and may be telescopic so that the section in which the chain is shortened may be varied. Alternatively the two sets of tracks at each side may be capable of bodily lateral movement together or apart to adjust the extent to which the chain folds. The overlapping portions of the guides 209, 210 may be continued throughout the remainder of the circuit of the chain. Where the chain initially engages a guide the latter is preferably flared. The guides may be shaped so that one set of articulations continue on a straight path from which alternate articulations diverge; alternate pins may then be long enough to engage a deflecting plate which is not engaged by the intermediate pins. The rollers 205, 206, 207, 208 may be replaced by rollers offset from the line of pins 203, alternate links carrying rollers offset on opposite sides to engage different guides. The tracks 209, 210 may be replaced by upper and lower forked tracks provided with a gate operated by passage of the chain rollers to divert the rollers alternatively to one side and to the other. As shown in Fig. 11 a pair of rotating members 511, 512 geared together may be provided with arms 514, 517 adapted at 515, 518 to engage alternate rollers 508 of a chain passing through a guide so to move them into engagement with guides 502, 503 flared at 504, 505 The paths of the rollers 508 in this construction may be modified by mounting the arms 514, 517 slidably in the corresponding member 511, 512 to engage at their inner ends with a fixed cam member which extends and retracts them against springs. In Fig. 13 alternate links 602 of 'a chain are formed with lateral extensions 607 carrying rollers 609 while alternate pins 604 are formed with rollers 606. As the chain moves from right to left the rollers 606, 609 engage with tracks 610, 611 respectively, the track 611 diverging at 612 to join a section 613 parallel to the track 610 so that the chain is shortened. Pins 615 on the links 602 carry links 614 provided with catches 616 which may be guided into engagement with the pins 604 by rollers 617 engaging a shaped track 618, 619, 620. The tracks 610, 613, 620 are terminated beyond the point at which the catches 616 are engaged, similar tracks being employed for releasing the catches. The length of the section in which the chain is shortened may be varied in this construction by varying the spacing between the latching and unlatching sections. The chains may be driven by sprockets in their unfolded portions or by chains carrying driving abutments in their folded or unfolded portions. They may be of the type in which the links are single bars connected by pins which carry rollers on one side of the links only. The invention is particularly adapted for use where a large amount of slack must be taken up in adjusting the tension in a driving chain or where the driving and tail sprockets may be moved relatively to one another.