Centrifugal brakes for focal plane shutters

摘要

In a focal plane shutter having two curtains which unwind from shafts after being released, the shaft controls a master gear, causing a keying pin on the latter to activate braking action on the curtain at a time interval near the terminal end of running-down movement of the curtain, as a pair of heavy expanding frictional shoes are driven to rotate at accelerated speeds and pressed against the internal surface of a fixed drum by a centrifugal force. During the shutter cocking operation, the key is taken out of connection with the brake so that the driving torque of the film winding shaft is correspondingly decreased.