parallel motion

noun

a mechanism arranged so as to impart rectilinear motion to a rod connected to a lever that moves through an arc.

Origin of parallel motion

First recorded in 1820–30

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

This form was objectionable, as the whole effort of the engine was transmitted through the parallel-motion rods.
A History of the Growth of the Steam-Engine
Robert H. Thurston
I contrived a sectional model of a complete condensing steam-engine of the beam and parallel-motion construction.
Stories of Invention
Edward E. Hale