Stoneblower

An alternative to the use of a ballast tamper, the totally self-contained machine levels track without the use of a large gang of workmen.

[1] A "frog" device which attached ahead of the machine reported measurements one metre apart of the altitude, relative to the starting point, of each rail head, at each sleeper, to an accuracy of 0.25 mm.

Deflection indicators on each side reported height deviation at the 50 cm point between the two axles.

Electromagnetic sensors flagged the location of the steel Pandrol clips which bind the rails to the sleepers.

Expected results were not achieved in practice,[2][3] and British Rail continued to use the ballast tamper.