Joy valve gear

<div style="float: right>thumb|right|Joy Valve Gear Diagram<!-- Deleted image removed: thumb|right|Lew - one of four similar locomotives owned by the L&B using Joy valve gear --></div>Joy valve gear is a type of locomotive valve gear, patented in 1870, where the movement is derived from a vertical link connected to the connecting rod. The vertical movement is translated into the horizontal movement required by the valve spindle by a die block moving in a slide which can be varied in inclination. The necessary 90 degree phase shift is obtained not from an eccentric as with most designs but from the 90 degree phase difference between the horizontal and vertical components of the motion of the connecting rod.

Joy gear was also used by John Fowler & Co. and several other steam traction engine manufacturers.

Designed by David Joy (1825&ndash;1903) Locomotive and Marine engineer, Joy valve-gear was used extensively on L&YR and LNWR locomotives, and also by the Manning Wardle-built narrow gauge 2-6-2 locomotives of the Lynton & Barnstaple Railway.

The last locomotives with Joy valve gear to remain in service with British Railways were the LNWR G2 and G2A classes, one of which is preserved.

References

See also

• Extracts from the Diaries of David Joy:

• A software simulation of Joy - and other common valve gear configurations - is available for download from:

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