GB1265983A - - Google Patents

Abstract

1,265,983. Overload clutches. A. J. BRADLEY. 15 Sept., 1970 [17 Sept., 1969], No. 45758/69. Heading F2C. An overload clutch comprising a hollow shaft 10 fitted over an input shaft 11 and on which an output clutch member 12 is rotatable has balls 17 carried by a freely rotating annular plate 18 transmitting the drive from a clutch member 19 mounted by splines 20 on the shaft 10. A twin spring assembly 23 urges the member 19 into driving engagement the outer spring 26 allowing axial disengagement at a normal running overload while an inner spring 27 maintains engagement during larger starting torques. The spring 27 abuts an abutment 31 which in the stationary position shown has a small clearance with pins 33 urged inwards by a spring 41. On starting slight initial separation of the clutch plates engages the pins 33 with the abutment 31 held by the spring 27 but upon increase of speed centrifugal force will withdraw the pins 33 out of engagement with the abutment 31 after the torque has fallen sufficiently to allow the spring 26 to restore the clearance between the pins 33 and the abutment 31 so that the drive is only maintained by the spring 26 allowing disengagement at the running overload torque. The overload disengagement can be preset by adjusting the spring loadings by screw abutments 24, 25 locked by a screw 28. In a modification a positive drive is provided during starting by firing the abutment 31 on the shaft 10 and then the spring 27 is omitted. In an alternative arrangement the balls may be located in curved slots or other means may be provided such that the balls move radially outwards upon disengagement into positions in which the recesses in the clutch members are not contacted. In this case manual restoration of the balls is necessary after disengagement.