hydraulic ram

plural hydraulic rams

1. A water pump in which a flow of water is intermittently halted by a valve so that the flow is forced upward through an open pipe, usually into a reservoir.

   Synonyms: hydram, ram pump

2. A hydraulic cylinder with a piston activated by pumping hydraulic fluid into the cylinder.

   The sleeper squarer manufactured by Permaquip is used to push sleepers back into their correct alignment, using hydraulic rams.

   2026 July 8, “RAIL Live 2026 exhibits”, in RAIL, number 1065, page 54

   1 more example

   The lifts are operated by means of a hydraulic ram with wire ropes, which derives its pressure from a small pump driven by an electric motor.

   1961 October, “Car carriage by rail - at home and abroad: 1. New B.R. "covered wagons"”, in Trains Illustrated, page 596

3. Used other than figuratively or idiomatically: see hydraulic, ram.