dynamometer car

plural dynamometer cars

1. rail transportA piece of railway rolling stock used to measure various aspects of a locomotive's performance.

   Wide open, a 4000 consumed up to 22 tons of coal and 100,000 pounds of water an hour and produced in one authenticated dynamometer-car test 6290 drawbar horsepower at 41.4 miles per hour.

   1959, Steam's Finest Hour, edited by David P. Morgan, Kalmbach Publishing Co., referring to the Union Pacific "Big Boy" 4-8-8-4

   1 more example

   More trials of diesel locomotives with fitted mineral trains have been observed. On October 31 a Brush Type 2, No. D5834, was seen on the Doncaster-Scunthorpe line with dynamometer car and 32 loaded wagons.

   1963 January, “Motive power miscellany”, in Modern Railways, page 64