Joy valve gear is a type of steam locomotive valve gear, designed by David Joy (3 March 1825 – 1903), Locomotive and Marine engineer, and patented (no. 929) on 8 March 1879.[1] The British patent has not been found but the US patent (US252224 of 10 January 1882) has.[2] Joy's gear is similar to Hackworth valve gear but has a compensating mechanism which corrects for "the slight inequality in the motion of the valve arising from the arc of the lever".[3]
The drawing (right) shows the Joy gear as applied to a London and North Western Railway locomotive.[4] The US patent shows several modifications of the gear. In figure 6 of the patent, one of the levers has been replaced by a slide.
On 10 January 1882, Mr. Joy received U.S. Patent No. 252,224 for the invention.
- ^ "David Joy's Diaries". 1878–9 Winter. Archived from the original on 4 March 2015. Retrieved 10 February 2015.
- ^ "Espacenet - Original document". worldwide.espacenet.com. Retrieved 20 January 2021.
- ^ Lines 35-50 of the US patent specification
- ^ Scientific American Supplement, No. 458, October 11, 1884 by Various