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The Walschaerts valve gear on a steam locomotive (a PRR E6s).. 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.
[5] [7]: 18 Early American locomotives had bar frames, made from steel bar; in the 20th century they usually had cast steel frames or, in the final decades of steam locomotive design, a cast steel locomotive bed – a one-piece steel casting for the entire locomotive frame, cylinders, valve chests, steam pipes, and smokebox saddle, all as a ...
The Hackworth valve gear is a design of valve gear used to regulate the flow of steam to the pistons in steam engines. It is a radial gear , with an actuating lever driven from the crank. The drive may be taken directly from the crank or indirectly via a return crank (as in all pictures).
Diagram showing lap and lead and their relation to valve travel. When on the move, a steam locomotive requires steam to enter the cylinder at precise times relative to the piston's position. [3] This entails controlling the admission and exhaust of steam to and from the cylinders with a valve linked to the motion of the piston. [3]
The Kuhn valve gear was not as widespread as the classic Walschaerts valve gear as its production costs were higher. One advantage of the Kuhn slide is that it runs equally smoothly in either direction. For that reason it was preferred on tank locomotives which, for operational reasons, often had to run backwards for long periods.
The Walschaerts valve gear is a type of valve gear used to regulate the flow of steam to the pistons in steam locomotives, invented by Belgian railway engineer Egide Walschaerts in 1844. [ 1 ] [ 2 ] The gear is sometimes named without the final "s", [ a ] since it was incorrectly patented under that name.
The gear was first tested on Mikado 586 in February, 1913 at Southern Knoxville Shops. It was specified for some USRA standard locomotive designs, though many locomotives constructed to these patterns used Walschaerts or Baker valve gear instead. The Southern valve gear was used on many Southern Railway locomotives, including survivors 630 and 722.
The Baker valve gear replaces the expansion link of the Walschaerts gear with an assembly of levers and links which produces the same effect of allowing continuous variation valve travel. The remainder of the gear is the same, so that the return crank and combination lever take the same form, although the proportions are usually modified.