The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in
The Walschaerts valve gear on a steam locomotive (a PRR E6s).
Soo Line 346 in 1961, showing the Kinkan-Ripken arm on the connecting rod at the right hand edge of the picture
Stephenson's Valve gear. Two eccentrics at nearly 180-degree phase difference work cranks from the main drive shaft. Either can be selected to work the valve slide by shifting the slotted expansion link.
Baker valve gear assembly