Timer switch using controlled return of depressed pushbutton - has locking ring with projecting pin which can be held in bayonet mount in depressed position for permanent contacting

摘要

The timer switch has a push-button (3) forced inwards against a spring bias to cause air to be forced out of a chamber, which slowly fills up again, via a control valve, to force the push-button (3) back outwards. A locking ring (4) surrounds the push-button (3) and can pivot through a given angle to lock the push-button in the depressed position to allow the switch to be permanently held in the on position. Pref. the push-button (3) has a radially projecting pin and the locking ring (4) has an L shaped notch, one part of which extends in the axial direction of the push-button (3) to allow its return, with the other part retaining the pin to prevent return of the push-button (3). The switch can be used for stairwell lighting etc. and readily allows either self-timed switching or permanent manually controlled switching.