GB732465A - Improved power transmission mechanism - Google Patents

Abstract

732,465. Hydraulic machines. GENERAL MOTORS CORPORATION. Nov. 28, 1952, No. 30162/52. Class 69 (2). [Also in Group XXX] An actuator is provided with alternative hydraulic, and screw and nut drives, each of which can operate the actuator in both directions. The hydraulic mechanism comprises a piston 40 which can be reciprocated in a cylinder 22 by the introduction of fluid into a space 41 or 42, and which carries a ball thread nut 56 co-operating with a reversible screw 50. Before the fluid is admitted to space 41, or 42 a clutch element 61 on a bell - shaped member 60 secured to the screw, is engaged with a clutch element 62 held against rotation by the braked motor 100 so locking the screw and preventing the piston from moving, but simultaneously with the admission of fluid to the cylinder, fluid is also admitted to the left-hand end of an annular space 26 so moving an annular piston 75 to the right against the action of springs 71 and allowing weaker springs 63 to disengage the clutch elements 61, 62. Thus, the screw and the piston are free to move. The alternative drive is effected by an electric motor 100 which has an electromagnetic brake 106 and which drives a worm-wheel 42 through a reduction gear (not shown). This wheel 42 is rotatably mounted on member 60 and has an extension 66 which slidably engages lugs 68 on the clutch element 62, so that when it is rotated it drives the screw through the engaged clutch elements 61, 62. Limit switches 131, one only of which is shown, are actuated at the ends of stroke by spring-loaded push-rods (not shown) engaged by the piston 40 and piston-rod extension 47. A remote indication of the position of the piston is effected by a rotary potentiometer 33 which is rotated by an axially fixed sleeve 162 having a helical slot engaged by a lug 169 on a rod 168 secured to the pistonrod. Specification 730,258 is referred to.