Patent GB-745759-A (GB)
Title: Torque control clutch device
IPC: B25B23/14
Filed: 1953-09-16
Abstract: 745,759. Overload release clutches. CHICAGO PNEUMATIC TOOL CO. Sept. 16, 1953 [Sept. 18, 1952], No. 25617/53. Class 80(2) A torque-release inclinedtoothed clutch of a power tool such as a wrench, or other apparatus, has lock-pawls 102 for holding the toothed members 63, 83 out of engagement and completely separated until manually permitted to re-engage as by releasing the usual axial engaging pressure on the tool. The clutch includes a freely mounted intermediate plate 63 having on its forward and rearward faces clutch teeth 72, 78 respectively engaging teeth 61, 84 on an output clutch plate 52 axially fixed but rotatable on a hollow input shaft 26, and on an input clutch plate 83 slidable on ball-keys 93 on the input shaft 26 which last-named 26, is splined to a motor shaft 22. Plain teeth 53 on the forward face of the output clutchplate 52 are for engagement with similar teeth 54 on a final output clutch member 33 fast with a tool holder 29, which slides rearwardly in the input shaft 26 against an internal spring 35 when axial thrust is applied manually to the motor to engage the clutch 52, 33 to commence operation, Fig. 8a condition. Motor torque then causes inclined sides of the forward teeth 72 on the intermediate clutch plate 63 to ride up the complementary teeth on the output clutchplate 52, until arrested by contact of axial faces 65 of these teeth, Fig. 8b position, the inclination (45 degrees) of the teeth being greater than that (30 degrees) of the rearward clutch teeth 78 to give them preced- ;ence in axial movement. Tool drive now ensues in the Fig. 8b condition until overload causes the inclined teeth 84 of the input clutch-plate 83 to ride up the complementary rear teeth 78 of the intermediate clutch-plate 63, moving the input plate 83 rearwards against a main loading spring 95, whereby inclined surfaces 106 in a sleeve portion 89 of the plate 83 permits outward movement of three lock-pivots 102 under the influence of a wedge 43, loaded rearwards by the internal spring 35 and slidable freely in the hollow input shaft 26 and on a centre post 37 tied to the manual clutch member 33. The inclines of the lock-pawls 102 and complementary surfaces are such that the inner spring 35, acting outwardly on the pawls 102 is sufficient to hold the input clutch-plate 83 in any rearward disengaged position in opposition to the main loading spring 95. In this condition the intermediate plate 63 is torquefree, and a cylindrically curved disc spring 74, reacting on a snap ring 76, is able to thrust it forwards, restoring it to its initial position and completely separating its now stationary rear teeth 78 from those of the rotating input clutch-plate 83, Fig. 8d position. To restore initial conditions the operator releases axial pressure on the tool body, whereupon the internal spring 35 moves the manual clutch element 33 to its extreme forward disengaged position, Fig. 1, in which a collar 49 on the internal rod 37 reacts the wedge 43, permitting the main loading spring 95 to overcome the lock-pawls 102 and move the input clutchplate 83 forwards into re-engagement. The load-breaking clutch teeth 84, 78 have inclined crest portions 80 at a shallow slope (75 degrees) for rapid final break. Spring- loads and rates are stated and the main loading spring 95 is adjustable by screwing a rear abutment collar 96 after removing the motor for its splined shaft 22 to release a ball lock 99. Operation is the same for both directions of drive.