GB861345A - Arrangement for unwinding warp threads in weaving looms - Google Patents

Abstract

861,345. Letting off and tensioning warps in looms. PICANOL-CAMPS, J. Jan. 30, 1959 [Jan. 31, 1958], No. 3464/59. Class 142(2) In a positive let-off motion in which rotation of the beam is controlled by the tension of the warp acting on a movable tensioning roller, a feeler adjusts the leverage of a balance weight for the tensioning roller in accordance with the amount of yarn on the beam. The tensioning roller is locked in position during shedding. The warp passes round a back rest constituted by a roller whose bearings can be clamped to produce a braking effect. Controlling let-off. The warp beam 1 is rotated by a ratchet-operated worm drive (not shown), the pawl being actuated by a rod 16 from a slide 18 oscillated by the slay 29 through a link 26. The slider is slotted to embrace a fixed pivot pin 19 upon which it is vertically movable to alter the ratio of its two arms, and hence alter the stroke of the pawl The slider is supported by a roller 22 running in an arcuate slot 23 in a lever 24 which is coupled by links 33, 38 to a shaft 43 carrying a tension roller 46, whereby an increase in the tension of the warp depresses the lever 24 to increase the stroke of the pawl. The tension roller is loaded by a weight 61 on a lever 36 pivoted at 37. To compensate for the changing line of action of the warp on the tension roller as weaving proceeds, a feeler 77 resting against the yarn on the beam is coupled to the weight by links 72, 62 to move the weight further away from the pivot 37 as the beam empties. To prevent excessive oscillation of the shaft 43 during the loom cycle, a brake shoe (not shown) is pressed against a sector 42 by a cam when the slay is at the rear part of its stroke. Tensioning warp. By tightening nuts 56, the back rest roller 49 can be braked or completely clamped to increase the tension in the warp above that determined by the tensioning roller.