GB573254A - Improvements in or relating to pawl-and-ratchet wheel mechanism - Google Patents

Abstract

573,254. Variable-speed ratchet gearing. C.-W. ENGINEERING CO., Ltd., and SANDERS, J. H. Nov. 30, 1943, No. 20004. [Class 80 (ii)] Relates to ratchet gearing in which a feeding pawl 22 on an oscillatable lever 14 engages a ratchet wheel 12, the number of teeth of which that can be engaged by the pawl 22 being controlled by a cam 44 on a slipper plate 42. The latter can be adjusted by a knob 52 connected to a worm 48 engaging teeth 46 on the slipper plate 42. A check pawl 28 pivoted on a fixed pivot 30 prevents return movement of the ratchet wheel 12, According to the invention, holding means associated with the check pawl is arranged to engage the slipper plate and hold the latter against the reaction of the feed pawl when the feed pawl is moving backwards for disengagement from the ratchet wheel and the check pawl is manually disengaged from the ratchet wheel. As shown, the slipper plate 42 has a notch 78 providing a shoulder 80. A pivoted lever 74 has a lug 84 adjacent the stem 40 of the pawl 28 and a lug 82 adjacent the perimeter of the slipper plate 42. A handle 66 is connected to the stem 40 by links 58, 60. In operation, when it is desired to release the load, the knob 52 is operated until the pawl 22 can engage only a single tooth. This brings the shoulder 80 in line with the lug 82. During the feeding stroke, the handle 66 is pulled to release the check pawl 28 and cause the stem 40 to engage the lug 84 and move the lug 82 into the notch 78. On the return movement of the lever 14, the pawl 22 is forcedly removed from the ratchet wheel 12 which spins backwardly to relieve the load. The engagement of the lug 82 with the shoulder 80 prevents the blow reacting on the slipper plate adjusting gear 46, 48, 52.