direct-acting

[ dih-rekt-ak-ting, dahy- ]

/ dɪˈrɛktˌæk tɪŋ, daɪ- /

(of a steam pump) having the steam pistons connected directly to the pump pistons without a crankshaft or flywheel.

Origin of direct-acting

First recorded in 1855–60

In a direct-acting engine the throw of the crank is equal to the stroke of the piston.

An Introduction to Machine Drawing and Design |David Allan Low
Each was fitted with a Blake, horizontal, direct-acting, vacuum pump.

Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910 |B. H. M. Hewett
Fishers carriages were driven by direct-acting engines, one cylinder on each side of the smoke-box.

Automobile Biographies |Lyman Horace Weeks
A vastly simpler form of pumping-engine without fly-wheel is the now common “direct-acting steam-pump.”

A History of the Growth of the Steam-Engine |Robert H. Thurston

Direct-acting compressors are liable to center when doing work at slow speed.

Scientific American Supplement, No. 799, April 25, 1891 |Various