GB622139A - Improvements in control levers for machinery parts - Google Patents

Abstract

622,139. Cramps. ROBERTSHAW, E. G. F. Nov. 18, 1946, No. 34075. [Class 61(ii)] [Also in Group XXIV] Operating mechanism for the sliding jaw 19 of a joiner's cramp comprises an operating lever 25 pivoted at 23 to the fixed jaw 21 and coupled by a link 27 to a sliding pawl 30 co-operating with teeth on a rack bar 31 secured to the sliding bar 20 of jaw 19. Also mounted on the pivot 23 is a handle 24 having a certain amount of rotary and lateral'movement relative to the lever 25 allowed for by a pawl 33 pivoted at 32 to said lever and having an end 34 cranked around the handle. The pawl 33 also has a locking tooth 43 co-operating with teeth on a quadrant 44 and a pair of laterally disposed cam surfaces 35, 36 adapted to co-operate with a spring-loaded latch 39 pivoted at 37 on the handle 24. With the parts in the positions shcwn, the end 38 of latch 39 is engaging the cam surface 36 of pawl 33 to hold it out of engagement with the quadrant 44 so that the handle 24 may be rotated freely to operate the lever 25 by engagement with the pivot pin 32 and so operate the jaw actuating pawl 30. On the required movement being completed the handle 24 is moved laterally to disengage the latch 39 from the cam surface 36 and engage it with the cam surface 35 under the tension of its spring, which forces the pawl 33 with its tooth 43 into engagement with the locking quadrant 44. For unlocking, the handle 24 is moved laterally in the opposite direction, the end 38 of the latch 39 being raised to engage cam surface 36 again, by a cam surface 41 on a cranked arm 42 on the lever 25 engaging the latch, and so lifting the pawl 33 from engagement with the quadrant 44.