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 on 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 "2 to 1" or "conjugating" lever and the "equal" lever). The gear is sometimes known as the Gresley-Holcroft gear, acknowledging Holcroft's major contributions to its development.
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- ⭐ Core Definition: Gresley conjugated valve gear
- Gresley conjugated valve gear in the context of Nigel Gresley
Gresley conjugated valve gear in the context of Nigel Gresley
Sir Herbert Nigel Gresley CBE (19 June 1876 – 5 April 1941) was a British railway engineer. He was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer (CME) of the London and North Eastern Railway (LNER). He was the designer of some of the most famous steam locomotives in Britain, including the LNER Class A1 and LNER Class A4 4-6-2 Pacific engines. An A1 Pacific, Flying Scotsman, was the first steam locomotive officially recorded over 100 mph in passenger service, and an A4, No. 4468 Mallard, still holds the record for being the fastest steam locomotive in the world (126 mph).
Gresley's engines were considered elegant, both aesthetically and mechanically. His invention of a three-cylinder design with only two sets of Walschaerts valve gear, the Gresley conjugated valve gear, produced smooth running and power at lower cost than would have been achieved with a more conventional three sets of Walschaerts gear.
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