GB1048124A - Improvements in or relating to overload release devices - Google Patents

Abstract

1,048,124. Overload release positive clutches. CAMPBELL & ISHERWOOD Ltd. Aug. 16, 1963 [May 18, 1962], No. 19184/62. Heading F2C. An overload release positive clutch between a driving shaft 10 and a driven sleeve 11 comprises rollers 19 engaging radial wedge-shaped grooves 15 in a flange fast with the driven sleeve and caged in slots in a flange 17 rotatively fast with the driving shaft, increasing torque loading causing the rollers to ride out of the grooves and force an engaging plate 20 rightwards against the bias of adjustably compressed springs 21 acting through a thrust plate 25, a main ball 24 and three trains of balls 23, 22, the latter engaging a chamfered surface 26 around the inner side of the engaging plate. Additionally, when stationary, and at relatively slow speeds, masses 34 are biased radially inwards of a carrier 32, 38 fast on the driving shaft 10 by springs so that cam faces 35 at their inner ends engage a cammed spigot 36 on the thrust plate 25 to reinforce the springs 21 in maintaining the clutch in engaged condition. Thus under these circumstances, a relatively large torque can be transmitted between the driving shaft 10 and the driven sleeve 11 before the rollers 19 ride out of the grooves 15 and force the engaging plate 20 towards the carrier 32, 38 for complete clutch disengagement. At relatively high speeds, however, the masses 34 fly radially outwards against the bias of their springs, so that their cam faces 35 no longer engage the cammed spigot 36 on the thrust plate 25. The springs 21 then alone maintain the clutch engaged, so that disengage. ment can be effected by a smaller transmitted torque. Re-engagement is effected by depressing a button 39, so that pins 40 push the engaging plate 20 back over the balls 22 &c. to the position shown. A housing 14 surrounding the clutch acts as an oil reservoir.