Safety gear for e.g. up=and=over garage door - has secondary counterweight manoeuvred by pulley block and resisting reversal of door movement

摘要

The safety mechanism comprises a counterweight(1) which is manoeuvred by a pulley block and affords absolute safety to potentially dangerous counterbalanced elements, e.g. an up and over garage door. The door may be displaced with the assistance of a prim. counterweight on pulley-guided cables, and the additional counterweight (1) may be fixed to the original. The mechanism stabilizes the leaf of the door in the event of strong winds etc. The action of the additional counterweight increases safety factors and opposes the reversal of a manually effected door movement. The pulley-block(4, 7) compensates for the additional weight(1) and may be operated by a crank-handle(5). The block includes a brake of which the capacity considerably exceeds the forces applied by the weight (1). The brake may retain one of the counterweights should the cable to the prim. counterweight be ruptured.