During the 1930's the LMS planned elaborate new locomotive testing facilities, including a new mobile test train (known as the Mobile Test Plant) and the Locomotive Testing Station at Rugby which was a joint project with the LNER. Both railways planned new dynamometer cars and ordered three Swiss Amsler hydraulic dynamometers, the third for incorporation in the stationary test plant at Rugby.

Construction of the new LMS vehicle commenced at Derby C&W Works shortly before the outbreak of war in 1939, but it was not completed until a decade later, soon after the formation of British Railways in January 1948. Initial trial runs were made in late April 1949 and it ultimately made 1,086 scheduled test runs between May 1949 and July 1975, covering an estimated 147,616 miles. Although originally designed to test steam locomotives, in the event it was also employed to evaluate diesel and electric locomotives and also the Prototype High Speed Train on the East Coast Main Line in June 1973.

During its working life this vehicle has carried several liveries, i.e. LMS crimson lake, BR 'blood and custard' and latterly the BR Research Department 'Orange and Blue'. Restored in 1979 it has been lettered LMS in recognition of its origins although not actually completed until after 1947.

The above information is provided - courtesy of the National Railway Museum.

It is now cosmetically restored into its former LMS livery and housed at Barrow Hill, Derbyshire

A description of the Mobile Test Plant 

The Mobile Test Plant comprised the LM Region No.3 Dynamometer Car M45049, Mobile Test Units Nos. 1, 2 and 3 M45053, M45054 and M45055 and a special locomotive tender which were all designed and built by the LMS at Derby C&W Works in 1938 but not completed until after WW2.

The main Instrument Room in the Dynamometer Car, accommodated the Control Desk for the Mobile Test Units, as well as housing the Recording Table which provided a continuous record of speed, drawbar pull, horsepower etc. The various multi-point thermometers, draught gauges etc. were also housed in this room.

A smaller room, the Indicator Compartment, contained a Farnborough Indicator which furnished indicator cards on a crank angle base, whilst another compartment contained apparatus for continuous smoke box gas sampling during tests.

The Mobile Test Units, were electrically braked vehicles, which could automatically keep the speed constant, irrespective of gradient, by varying the load as required. The units were capable is being be used singly, in pairs or all three together, according to the speed and braking force required for each controlled test. Control was applied from the Dynamometer Car and speed could be regulated by hand or automatically.

The special Tender was equipped with a corridor allowing access to the footplate and the coal space was divided centrally, one side being used for test coal in one cwt bags, the other side for loose coal for periods not under test and for standby purposes. A water meter was fitted to give the amount of water taken from the tender.

Here are some pictures of the units which made up the Mobile Test Plant taken from the early BR test bulletins. A number of new photos of the inside of the dynamometer car and of a Mobile Test Unit under construction have recently been added

All photos are BR Official unless otherwise indicated

The MTU's survived until 1976 and at least one was re-painted into R&DD red and blue livery. M45053 is part of the national collection although in very poor state of preservation. Look here for a couple of photos on Ben Williams' excellent Departmentals.com site.

The ex-LMS dynamometer Car No:3, running number M45049, is preserved as part of the National Collection by the NRM and is presently at Barrow Hill where it has been re-painted into LMS crimson lake livery.

45054 and 45055 were sent to Cashmores at Great Bridge where they were cut up.