Messrs. Spencer and Dawson, who were the General Manager and Engineer respectively at Bradford, took out a patent for a variable-gauge truck which would permit through running on the service between Bradford and Leeds, as the two systems were of different gauges.

This photograph shows what I assume to be the first modified truck, which was based on a Peckham cantilever truck. It is in the narrow (4'-0") gauge position. When traversing the taper track the truck would be unlocked to allow the wheels and gear wheels to slide outwards along the axle, along with the brake gear, to the standard gauge position.

This design led to a non-standard motor with drive at both ends through extended pinion wheels.

If it is the first truck it was fitted to Bradford's Brush car 124 which started the trial operation of the service from 22nd April 1907. Ultimately over twenty cars were modified to work the service, but the First World War took its toll on the maintenance of these complex trucks and the service was quietly abandoned in early 1918.