train-pipe

from The Century Dictionary.

• noun In a continuous train-brake or power brake for railway-trains, the pipe which connects the sonrce of power or stored energy on the locomotive with the brake elements under each car. In the air-brake it is the pipe connecting the compressing air-pump on the locomotive with the storage air-tanks under each car, by means of which the engineman in the locomotive sets and releases the brakes by causing variations of pressure in the pipe and on the face of the piston in the triple valve on each car. Now called brake-pipe. See triple valve.