Patent GB-799800-A (GB)
Title: Cam and jack arrangements for flat-bed transfer knitting machines
IPC: D04B7/06
Filed: 1956-11-08
Abstract: 799,800. Knitting-machines. PRIOR, A. E. Nov. 8, 1956 [Nov. 23, 1955], No. 34149/56. Class 74 (2). In a machine having two horizontally opposed flat beds, in tricks 15 in which double-ended latch needles 18 are reciprocated by cams in a slidable carriage, acting through jacks 16, 17, and between which beds the needles may be transferred, the lower edges of the jacks have a convex profile, to provide humps 33 which act as fulcra, and the upper edges have depressions 35 to permit rocking of the jack; and, after the free end of a needle to be transferred has been engaged by the accepting jack, the needleengaging end of that jack is held down on the needle by the associated one of a pair of bars 30 on the carriage, whilst the relinquishing jack is positioned with its depression below the other bar 30 so that it can rock about its hump to release the needle. The bars 30 and other bars 31 hold down the front ends of the jacks during knitting, to guard against unintentional release of the needles by reason of (say) jack bounce; but the bars 31 do not extend into zones B within which needle transfer takes place. For any stroke of the carriage in either direction along the needle beds, the needles may be selected so that the butts of their jacks follow a transfer path " a," a knitting path " b," or a non-knitting path " c." In following the ordinary knitting path " b," a jack butt enters the cam track between guard cams 64, 66 or 65, 66, rises over a clearing cam 67 or 68, to cause its needle to clear the loop drawn in the previous course, moves in a relatively straight path under the guard cam 64 or 65 to the centre of the track, engages a centre flap cam 43 and swings it into a trailing position, whilst its needle takes yarn from a feed hole 40, passes down this flap cam and under a stitch cam 48 or 47 to cause its needle to knit, and passes out of the track between the other clearing cam 68 or 67 and the other end of the guard cam 66. To vary the stitch length, the stitch cams are slidable parallel to their faces by a double snail-cam 59, rotatable by a finger knob and acting against return springs 56. The clearing cams may be swung to inoperative position (shown dotted in Fig. 6 for one of them) about pivots 69 by finger buttons 74-77 which slide in slots 78, are connected to the cams by straps 73 and act against return springs 72. The transfer track " a " joins the knitting track " b " just before the centre of the cam system; and thus any jack from which a needle has been transferred will join and thereafter idly follow the knitting track. To transfer a needle, its jack is positioned manually, so that its butt bears against a bar 29 which each bed carries. This puts the butt of the jack into track " a " and it rides over that part of cam 64 (say) corresponding to a span B, whilst the receiving jack, riding idly in the knitting track of the other bed, mounts the opposite clearing cam 67 (say) to the point where its bight is under its bar 29, rocks to engage the needle and starts to descend its cam 64, its latch guard finger 28 now coming under the span B of its bar 30 to prevent release of the needle. The relinquishing jack, however, has its depression 35 under its bar 30 and may therefore rock to release the needle, being thereafter passed by cam 45 (say) into the knitting track. Whenever a clearing cam is in its inactive position, jack butts approaching will so pass through the cams that their needles fail to clear or to take yarn. Thus tubular fabric may be knitted by disabling two diagonally opposed cams, or half cardigan stitch by disabling one cam, if the cams are so proportioned that the butts can proceed in a straight line to the flap cam. By disabling the related clearing cam or cams, moving selected jacks by hand to bring their butts against the bar 29 and moving the opposed jacks in the other bed to non-working position (to avoid needle transfer) the needles associated with the selected jacks may be made to knit to the exclusion of all others. The yarn feed hole 40 is in the centre of a plate 39 slidable along grooves 37 on the underside of the carriage, and the yarn may run to the hole by way of either end of a groove 41 in the plate which plate, whilst normally retained by abutment of lugs 42 against the carriage edges, may be flexed and removed endwise.