piston valve

Noun

piston valve (plural piston valves)

1. A valve which uses a hollow or double piston sliding in a cylinder to direct fluid along one of two paths
   • We already know that a balanced slide valve requires about half as much power to move it as an unbalanced valve, but the piston valve requires only about half as much as the balanced valve.1898, “A Plea for the Piston Valve”, in Bulletin of the International Railway Congress Association, volume 12
   • The three cylinders of these engines are 18½ in. dia. by 26 in. stroke; and as the three piston valves were all between the frames, it resulted in the monoblock casting being weak, so far as the centre cylinder was concerned, with the result that the life of these castings left a good deal to be...1944 November and December, “Conversion of L.N.E.R. "B16" Class 4-6-0 Locomotives”, in Railway Magazine, page 349