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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. It can also serve as a reversing gear. It is sometimes referred to as the ...
The Bulleid chain-driven valve gear is a type of steam locomotive valve gear designed by Oliver Bulleid during the Second World War for use on his Pacific (4-6-2) designs. It was peculiar to the Southern Railway in Britain , and borrowed from motor-vehicle practice in an attempt to create a compact and efficient design with a minimum of service ...
Calculating an exact answer to that question before computers was too much work. The easy approximation (used in Zeuner's and Realeaux's diagrams) is to pretend that both the valve and the piston have a sine-wave motion (as they would, if the main rod were infinitely long). Then, for instance, to calculate the percent of the piston's stroke at ...
During the 1830s, the most popular valve drive for steam locomotives was known as gab motion in the United Kingdom and V-hook motion in the United States. [3] The gab motion incorporated two sets of eccentrics and rods for each cylinder; one eccentric was set to give forward and the other backwards motion to the engine and one or the other could accordingly engage with a pin driving the ...
Some of the Union Pacific 9000 class locomotives were converted to a "double Walschaerts" valve gear, while later examples were built with roller bearings for the moving parts of the Gresley mechanism. In Australia, the VR S class Pacifics avoided many of the middle cylinder problems that beset Gresley by placing a 'set' in the axle of the ...
Gab valve gear was an early form of valve gear used on steam engines. Its simplest form allowed an engine to be stopped and started. A double form, mostly used on steam locomotives, allowed easy reversing. [1] Winding engine at Blists Hill. The red handwheel is the steam stop valve, the lever in front of the engine driver disengages the valve ...
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A similar arrangement transfers the motion via another roller tip to a second rocker arm. This rotates about the rocker shaft, and transfers the motion via a tappet to the valve. [clarify] Some OHC engines employ short rocker arms, also known as fingers, in which the cam lobe pushes down (rather than up) on the rocker arm to open the valve.