Dynamometer car

A dynamometer car is a railroad maintenance of way car used for measuring various aspects of a locomotive's performance. Measurements include tractive effort (pulling force), power, top speed, etc

The first dynamometer car was probably one built in about 1838 by Charles Babbage. Working for the Great Western Railway of Great Britain, he equipped a passenger carriage to be placed between an engine and train and record data on a continuously moving roll of paper. The recorded data included the pulling force of the engine, a plot of the path of the carriage and the vertical shake of the carriage. The work was undertaken to help support the position of the Great Western Railway in the controversy over standardizing the British rail gauge.