GB973333A - Improvements in impact clutches - Google Patents

Abstract

973,333. Overload slip couplings. ATLAS COPCO A.B. March 15, 1963 [April 2, 1962], No. 10309/63. Heading F2C. An overload slip coupling for power tools, &c. comprises a driving shaft 29, Fig. 1, having a rotary lost-motion spline coupling 52, Fig. 10, with a hammer mass 45 formed with an axial groove containing a rockable clutch dog 54, Fig. 7, which in the normal drive position is so tilted that its trailing edge 57 engages and transmits drive to one, 39, of two symmetrical camming ears 39, 40 constructed on an output anvil 25, 38. Radially projecting shanks 67, 68, Figs. 5, 10, on a spring 66 co-operate with a projection 64 on the driving shaft and an axial pin 62 on the clutch dog 54 to control the angular position of the clutch dog, angular movement of the driving shaft 29 relative to the hammer mass 45, as permitted by the lostmotion spline coupling 52, causing the clutch dog to tilt so that whichever of its two edges 57 is the leading edge is withdrawn into the hammer mass 45, Fig. 7. Since the parts are symmetrically arranged, the direction of rotation of the driving shaft 29 may be reversed. On overload of the anvil 38, the clutch dog 54 is tilted by the camming action of the engaged driven ear 39 on the anvil against the bias of the spring 66, and rides over the camming ear. The hammer mass 45 then rotates relatively to the anvil 38, Fig. 8, until the trailing edge 57 of the clutch dog 54 engages the camming ear 40 of the anvil, Fig. 9, and tilts the dog so that it rides over the ear. In this tilted position, the back face 55, Fig. 3, of the clutch dog 54 now gives a sharp blow with its leading edge to the front face 41 of the camming ear 39 on the driven anvil 38. During the rebound following the blow, the clutch dog 54 is tilted back by the spring 66 to the position shown in Fig. 7 and, if the overload has been surmounted, drive is recommenced. As shown, the shank of the spring 66 extends into a hole in the driving shaft 29, but alternatively it may extend into a hole in the driven anvil 25, 38. Reference has been directed by the Comptroller to Specification 934,010.