Patent GB-1050113-A (GB)
IPC: F16D43/208
Abstract: 1,050,113. Positive clutches. FISHER & LUDLOW Ltd. July 19, 1963 [July 21, 1962]. No. 28157/62. Heading F2C. A snap-action overload release positive clutch comprises driving and driven members arranged concentrically one within the other and each carrying abutments between which can be engaged roller or ball torque transmitting keys, the abutments on either the driving or the driven member each being mounted upon pivoted carriers spring-biased to maintain engagement between the abutments and the rollers &c., overload of the clutch overcoming the spring-bias so that the rollers &c. disengage from the abutments. In one form, a driving shaft 22 is fast with a disc 21 upon which carriers 26 are fulcrumed at 30, each carrier mounting a cylindrical abutment 25. A surrounding driven cup 23 mounts abutments 33, and rollers (or balls) 36 lie between the pairs of abutments 25, 33. Each roller &c. 36 is mounted at the outer ends of a pair of levers 38 connected by pivot pins 40 to the driving disc 21. Helical compression springs 42 act through adjustable thrust pads 44 to bias the carriers 26 radially outwards and maintain the abutments 25, 33, rollers &c. 36 in engagement, this outwards movement being limited by links 46 pivoting on the driving disc 21 and having pin-and-slot connections 48 with the carriers. Torque is transmitted in the clockwise direction from the driving disc 21 to the driven cup 23. On overload, the rollers &c. 36 are projected forwardly, over the abutments 33 in the driven cup, into peripheral recesses 41 in the driving disc 21, friction dampers comprising interengaging spring-biased cams, Figs. 6, 6a, 6b (not shown), connected with each of the pivots 40 of the roller-mounting levers 38, cushioning the engagement of the rollers with the recesses and retaining them therein. The clutch is reengaged by hand when rotation of the driving shaft 22 &c. has stopped, the rollers &c. 36 then being pulled back individually to the positions shown. In a modified form for transmitting drive in either direction of rotation, a driving shaft 22, Figs. 7, 8, 8a (not shown), is fast with a hub 21 having a tiltable, substantially triangular, carrier 26 mounted in a recess 28, the carrier either being fulcrumed about one of its ends 30a or alternatively tilted over to fulcrum about its other end 30b. Springs 42a bias the carrier to engage a cylindrical-shaped abutment 25 at its apex with a roller 36, Fig. 8a (not shown), in turn engaging a cylindrical abutment 33 in a driven cup 23. The roller 36 is free between the arms 38 of a carrier hub 69 in light friction engagement with the end of the driving hub 21, a nut 70 permitting adjustment of the friction engagement. On overload, the roller 36 is forced over the abutment 33 in the driven cup 23 as the carrier tilts from one position to the other, and is carried round until it is free to enter one or other of two recesses 72 in the driving hub. The clutch is then completely disengaged, and can be re-engaged, when the driving shaft 22 &c. has been brought to rest, on manual tilting of the carrier 26 back to its initial position and restoration of the roller 36 to the position shown.