GB853856A - Improvements in or relating to looms for weaving - Google Patents

Abstract

853,856. Dobby. BRITISH COTTON RESEARCH ASSOCIATION. July 28, 1958 [Aug. 1, 1957], No. 24367/57. Class 142(2). In a positive double-lift open shed dobby, Fig. 2, fixed bars 21, 22 receive the upper ends 19c of any hooks 19 whose lower ends 19b are not engaged with the lifting knives 17, 18; accidental displacement of the hooks on the bars is prevented by lowering locking bars 28, 29 to the positions 28a, 29a, the bar 29 being of comblike construction to pass between the jacks 12. The hooks are set by feelers 23, 24, of which the pair pertaining to the same baulk 11 are coupled together by a spring 25 which holds them against stops 26, 27 when they are not rocked by pegs 30 on a pattern barrel 16; the pegs on alternate lags 31 are staggered so that the feelers 23 are operated for one pick and the feelers 24 for the next. Pattern mechanism, Fig. 3. The pattern barrel 16 is driven by a pin 35 engaging an arcuate slot 36 in the striker wheel 34 of a Geneva motion 37, 38; when the dobby is reversed, the slot 36 provides the necessary re-timing between the operation of the feelers and the dwell of the lifting knives. A clutch 39 between the Geneva wheel 38 and the shaft 16a of the pattern barrel enables the barrel to be turned by hand, the Geneva wheel then riding out of the notches of the clutch against the action of a spring 40. For pick-finding, the pattern barrel is turned an even number of notches of the clutch. To bring all the warp threads to the same level, the barrel is turned only one notch; the feelers 23, 24, Fig. 2, are then operated when the corresponding hooks 19 are out of their range whereby, on turning the loom two revolutions of the crankshaft all the hooks become engaged by the knives 17, 18 and all the heald shafts are consequently lowered. Adjusting shed size, Fig. 1. The dobby is mounted at the side of the loom and coupled to the shafts 15 by links 13, 13x and bellcrank levers 14, 14x. The lower ends of the jacks 12 have three holes 12b to receive the links 13; the holes lie on an arc of a circle having its centre at the position occupied by the right-hand end of the links 13 when the shafts are in their lowermost position; when the shed opening is altered by moving a link 13 from one hole to another, the bottom shed line therefore remains unaltered at shuttle race level. Specification 733,777 is referred to.