SET OF SPRING COUPLINGS WITH REDUCED RADIAL CARRIER CAPACITY Russian patent published in 1997 - IPC

FIELD: drive for lowering and lifting of window screen by spring couplings. SUBSTANCE: coupling has shaft, first and second spiral wound axial springs for providing frictional engagement with shaft. Coupling is further provided with engagement devices, one for each spring, for selectively applying compression force to one end of each spring for preventing spring from rotation relative to shaft. Each frictional engagement device is extending in radial direction and symmetrically along shaft to reduce radial force induced by spring ends. EFFECT: increased efficiency, simplified construction and enhanced reliability in operation. 28 cl, 13 dwg