Patent GB-1517692-A (GB)
Title: Torque limiting clutch
IPC: F16D43/20
Filed: 1974-06-13
Abstract: 1517692 Positive clutches GIB PRECISION Ltd 12 June 1975 [13 June 1974 5 April 1975] 26229/74 and 14050/75 Heading F2C In an overload release clutch wherein torque transmitting balls or rollers 25 are carried by apertures 27 in a carrier or driving disc 28 which is positioned between a driven disc 20 and another disc 15, the discs 15, 20 are held a predetermined distance apart during clutch disengagement by spacer balls or rollers 34 carried by the carrier disc 28 and engaging tracks located axially relative to the driven and other discs, one of the tracks has recesses 35 in which the balls or rollers engage when the clutch is engaged. As shown, torque transmitting balls 25 normally engage recesses 29, 30 in driving and driven discs 15, 20 urged together by a spring 24. On overload the balls 25 ride out of the recesses 29, 30 and move circumferentially into receiving recesses 31 in the driven disc 20. The circumferential movement of the balls 25 rotates the carrier 28 and spacing balls 34 relative to the driving disc 15 so that when the balls 25 engage the receiving recesses 31 the spacing balls 34 abut the surface of the driven disc 20 and hold it at a predetermined distance from the driving disc 15. The spacing balls 35 abut a freely rotatable track 36 located axially relative to the driving disc 15 to permit free relative rotation between the driving and driven discs 15, 20 during clutch disengagement. A lost-motion pin-and-slot connection (38, 39, Fig. 8, not shown) between the carrier disc 28 and driven disc 20 prevents movement of the carrier disc 28 and balls 25 beyond the receiving recesses 31. During clutch disengagement the torque transmitting balls 25 are urged towards the receiving recesses 31 by springs (Fig. 8, not shown) or by coned surfaces of the apertures 27. To reset the clutch either the carrier 28 is rotated reversely to cam the balls 25 out of the receiving recesses 31 and thereafter move the balls 25 circumferentially until they re-engage the recesses 29, 30 or the driving member 15 is rotated reversely until the recesses 29 are aligned with the apertures 28 and thereafter the driving disc 15 and carrier disc 28 are rotated reversely together until the balls 35 re-engage the recesses 30 in the driven disc 20. Recesses (41, 42) in the carrier 28 and driving disc 15 are engaged by a tool for resetting purposes. In Figs. 19 and 20 (not shown), a pawl (500) fast with the driving disc engages ratchet teeth (502) in the carrier (28) when the recesses (29) in the driving disc (15) are aligned with the apertures (27) in the carrier (28). To reset the clutch the driven element is rotated forwardly, the balls (25) causing the carrier (28) to also rotate forwardly until the apertures (27) are aligned with the recesses (29). Thereupon the pawl (500) engages the ratchet tooth (502) and subsequent further rotation of the driven element urges the balls (25) into the recesses (29) and out of the receiving recesses (31). The driven element is then rotated until the balls (25) re-engage the recesses (30) and the spacing balls (34) re-engage the recesses (35). In Fig. 11 (not shown), the torque transmitting and spacing balls are replaced by rollers. In Fig. 10 (not shown), the pin-and-slot connection between the carrier and driven elements is replaced by a two-part carrier, the two parts having a lost-motion connection therebetween and one part is connected to the driven disc. Alternatively the pin- and-slot connection may be replaced by a friction connection. In Figs. 12-18 (not shown), circumferential ball guiding grooves are provided between the recesses and apertures of the driving, driven and carrier discs. In Figs. 21 and 22 (not shown) the intermediate disc is the driving disc which is positioned between a driven disc and a spring pressed freely rotatable disc. Torque transmitting apertures (630) are formed in the driven disc and the torque transmitting ball receiving apertures (631) and the spacing ball receiving recesses (635) are formed in the freely rotatable disc.