Valve gear
![The Walschaerts valve gear on a steam locomotive (a PRR E6s).](/Images/godic/202502/05/Walschearts_valve_gear4531.jpg")
4531.jpg")
![Baker valve gear assembly](/Images/godic/202502/05/Baker_valve_gear4532.jpg")
![View of Henschel & Son conjugated valve gear mechanism used on Victorian Railways H class locomotive, driven from the outside Walschaerts valve gear](/Images/godic/202502/05/H220motion34532.jpg")
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 cycle. It can also serve as a reversing gear. It is sometimes referred to as the "motion".