The complete assembly of linkages, rods, cranks, and levers that transmit power or control timing in a machine. Historically used in steam engineering to describe the valve gear and connecting rods of a locomotive, the term survives in heavy machinery to describe exposed, complex kinematic linkages working together.
Heard on the job
Shut down the main drive and lock it out before you get anywhere near that motion to grease the pins.
Also heard as
- motion work
Related terms
Valve gear
The mechanical linkage that controls the timing and duration of fluid entering and exiting a cylinder.
Crosshead
A sliding block that connects a piston rod to a connecting rod, absorbing lateral forces.
Bellcrank
A pivoting lever bent at an angle to change the direction of applied force or motion.