Brakes applied by springs or weights and released by vacuum

Full Title

Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems (arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions B60T8/00; valves incorporated in such systems B60T15/00) > with fluid assistance, drive, or release > the fluid being gaseous > Vacuum systems > Brakes applied by springs or weights and released by vacuum