vacuum brake

vacuum brake (plural vacuum brakes)

1. (rail transport) A brake used on trains, working on the principle of keeping up a vacuum in a continuous pipe or pipes extending under the train, and in brake-cylinders connected to them under each vehicle, the air being sucked out by ejectors or pumps on the locomotive.
   • 1951 January, “Diesel-Electric Branch-Line Locomotive for British Railways”, in Railway Magazine, page 71:

     Compressed air is used for the operation of certain contactors, the sanders, the horn, and the re-fuelling equipment, but vacuum brakes are fitted to the locomotive.

   • 1963 January, “A second chance on brakes”, in Modern Railways, page 1:

     Consideration of recent pronouncements and predictions shows second thoughts to be practicable, in particular, on the technical decision for which the previous B.T.C. regime was most hotly criticised by experts - the adoption of the vacuum brake as standard for the modernised British Railways. [...] The original decision to retain the vacuum brake was justified largely on grounds of the intolerable operating convenience that would ensue from a changeover.