Gresley conjugated valve gear [SEP] discoverer or inventor
Gresley conjugated valve gear
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 "2 to 1 lever" and "equal lever"). The gear is sometimes known as the Gresley-Holcroft gear, acknowledging
, but with the pivot point being moved back and forth by a lever from the other outside cylinder. See Gresley conjugated valve gear for more detail.
When it proved impractical to mount the conjugation apparatus behind the cylinders on the N1 Holcroft had to revise the design to have the apparatus in front of the cylinders. He did not wish to use an extension of the valve spindles, as on Gresley conjugated valve gear. Instead, Holcroft carried-forward the action of the combination lever assembly that controlled the fore and aft