Rock-shaft.
(Steam-engine.) a. A shaft with tappets which raise the levers of the puppet-valves in a certain class of steam-engines. b. The shaft, with levers, used for working the slide-valves, the notch of the eccentric rod dropping into a stud fixed in one of the levers; the links of the slide-valve spindle being attached to the opposite lever on the same shaft. [1961]