hydraulic ram

English

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hydraulic ram (plural hydraulic rams)

Used other than figuratively or idiomatically: see hydraulic,‎ ram.
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.
A hydraulic cylinder with a piston activated by pumping hydraulic fluid into the cylinder.
- 1961 October, “Car carriage by rail - at home and abroad: 1. New B.R. "covered wagons"”, in Trains Illustrated, page 596:
  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.