Electrically operated shutter closure for building openings

摘要

The closure uses an electric motor driving a winding drum for opening the shutter which has a counter-balancing spring arrangement incorporated to balance the downward movement of the shutter and a one-way clutch between the motor and the drum which slips at a pre-determined load. The winding drum (4), on which the shutter is wound is rotated, from one end, in either direction in a housing (5) by an electric motor (7) through a clutch (8). The clutch is so arranged that it slips if the load, during the lowering of the shutter, exceeds a pre-determined value, eliminating the need for a braking mechanism. At the other end of the drum is a shaft (9a) on which is wound a compensating spring (9) which is tensioned as the shutter is lowered.