The Gresley conjugated valve gear is a valve gear for steam locomotives designed by Sir Nigel Gresley, chief mechanical engineer of the LNER, assisted by Harold Holcroft. It enables a three-cylinder locomotive to operate with only the two sets of valve gear for the outside cylinders, and derives the valve motion for the inside cylinder from them by means of levers. The gear is sometimes known as the Gresley-Holcroft gear, acknowledging Holcroft's major contributions to its development.
New South Wales Government Railways D57 class 4-8-2, with Gresley conjugated gear visible at front below the smokebox. The longer 2 to 1 Lever is located on the right side of the locomotive, and the shorter Equal Lever on the left side.
The third cylinder and Gresley gear are visible below the smokebox of this 4-12-2.
Victorian Railways H class
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The Victorian Railways H class was an express passenger steam locomotive operated by the Victorian Railways from 1941 to 1958. Intended to eliminate the use of double heading A2 class locomotives on The Overland services on the steeply graded Western line to Adelaide, wartime restrictions led to only one locomotive being built. Nicknamed Heavy Harry, H220 was the largest locomotive ever built in Australia and the largest non-articulated steam locomotive to run on Australian railways.
Builder's photograph of H220, 1941
Detail view of the Henschel & Son valve gear mechanism
H220 leads the Albury Express out of Melbourne, past the signalbox at Essendon, circa 1949
H220, in static preservation at the Newport Railway Museum