Safety device for protection against the falling down of motordriven up and down moving objects

摘要

The driveshaft (10) has an insert (11) with an axially movable friction plate (12) against which two parallel pressure plates (20,22) having limited relative rotation are brought to bear by the spring-biased armature (18) of an electromagnet (17) when the latter is de-energised. The pressure plates have elevations with sloped edges on the faces turned towards each other, so that their relative rotation causes the elevations to slide over each other and to force the pressure plates apart.