vacuum brake

plural vacuum brakes

1. rail transportA 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.

   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.

   1951 January, “Diesel-Electric Branch-Line Locomotive for British Railways”, in Railway Magazine, page 71

   1 more example

   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.

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