James Thompson Marshall

James Thompson Marshall (1854, Glanford Brigg, Lincolnshire[1] - 1931, Knaresborough, Yorkshire[2]) was an English railway and mechanical engineer known for inventing the 'Marshall valve gear' for steam locomotive use.

At least one of J. T. Marshall's valve gears was a rotary type and the only known application was to the Austrian BBÖ Class 114 locomotive.

When the valve gear was in use, the motion was derived from two eccentrics, one of which gave lap and lead movement by swinging the link backwards and forwards on its suspension bracket.

The position of the radius rod die pin in the link determined the direction of movement and the cutoff.

Showing little advantage over the normal Stephenson link valve gear, it was removed from the C2 'Atlantic' in April 1907 to ease maintenance.