SCREW DRIVE FOR VERTICAL MOTION OF LOAD Russian patent published in 1994 - IPC

FIELD: load-hoisting machinery. SUBSTANCE: screw drive comprises screw 1 with operating nut 2 and auxiliary nut 3. Operating nut is attached to load 4 via spherical axial bearings 5, 6 without being capable of turning relative to said load, and takes the main load. Auxiliary nut 3 which bears no load and is intended to prevent the load from falling in case of sheared thread is disposed under the operating nut. Auxiliary nut carries thrust bearing 7 installed with a certain clearance from the operating nut. The nuts interact with each other via plates 8 disposed in slots of auxiliary nut, via cover 9 connected with operating nut, and via roller-type overrunning clutch 10 disposed in radial circular gap between the nuts so that clutch rings are rigidly connected, respectively, with operating and auxiliary nuts by means of keys 11 and 12. Roller overrunning clutch provides for lowering the load in case of sheared thread. Plates intended to lock the nonloaded auxiliary nut relative to the operating one are selected so that they would be sheared if the thread is sheared and the load is transferred to the auxiliary nut. EFFECT: improved design. 4 dwg