The earliest brakes were
probably ratchets on hand-powered windlasses. These, and all brakes
thereafter, were designed to stop and hold the elevator at a floor,
and are distinguished from car safeties that were designed to stop cars
in the event of an emergency. Hand brakes, operated by a pull-rope from
hand-powered lift platforms were of a band type around a drum on the
bull wheel shaft. A pull would activate a lever or a screw, thus tightening
the band. With the coming of electricity brakes were electrically opened,
then closed by springs when power drifted out of the solenoid coil.
Although the electric brake shoes usually operated on a drum fastened
to the worm/motor shaft an auxiliary brake periodically was used for
redundancy on the drive sheave shaft. Two brakes were sometimes used
on the worm shaft. Brakes were also both opened and closed by a small
motor. With the coming of variable voltage and gearless drive machines,
the braking was dynamic and the brake only came into action as a holding
device after the drive machine halted.
