a brake system, used on British and many overseas railways, in which the brake is held off by a vacuum on one side of the brake-operating cylinder. If the vacuum is destroyed by controlled leakage of air or a disruptive emergency, the brake is applied. It is now largely superseded by the Westinghouse brake system
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Examples from the Web for vacuum brake
In the 1886 tests there were five competitors—three buffer-brakes, one compressed-air brake, and one vacuum-brake.