Apparatus having mechanical timer for delayed operation of a sliding door

摘要

Apparatus comprising a first system for operating on a cable 12 from a cable pulling system, the first system is changed from a second condition, which opposes movement of the cable, to a first position, which allows movement of the cable, by a second system comprising a mechanical timer; the first system is changed from the second condition to the first after expiry of a predetermined time period. In use the cable pulling system 6 may be a spring wound drum 6 arranged to retract the cable 12 after manually opening the door; the apparatus may be arranged to hold the door open. The first system preferably comprises a brake lever (32, fig.4) which opposes rotation of a pulley and prevents the cable being retracted by the winding mechanism 6. The braking system has a clutch to allow unimpeded opening of the door. Preferably the mechanical timer is wound up by opening the door and upon expiry of time rotates cam (30, fig.4) to release the brake achieving delayed closing of the door. An override lever may be provided to release the brake when the door is manually closed and slack is detected on the cable (fig.7).