Motor Rail

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Simplex 40HP armoured 600 mm (1 ft 11 58 in) gauge, built for the British Army for World War I
Two models of Simplex locomotive at Alan Keef's works, 1999

Motor Rail was a British locomotive-building company, based in Bedford. In 1987 loco manufacture ceased, and the business line sold to Alan Keef Ltd of Ross-on-Wye, who continue to provide spares and have built several locos to Motor Rail designs.


Formed in 1911 as The Motor Rail & Tramcar Co Ltd, the company built petrol and diesel-engined locomotives, mainly for narrow gauge railways. In January 1916, the company answered a War Department tender for military supply railways. The specification was for a 600 mm (1 ft 11 58 in) gauge locomotive, with no more than 1ton of axle load per axle, capable of hauling up to 15tons at 5 miles per hour (8.0 km/h).[1]

The company designed a new locomotive, based around a square-set but with outer longitudinal "bent-rail" frame, mounted on two axles. The 2JO petrol engine manufactured by W.H.Dorman & Co of Stafford was centre-set longitudinally in the frame. This resultantly required the operator to sit above the engine facing to one side of the design, to enable mounting of the engine and Dixon-Abbott patent gearbox, which drove the unsprung axles through a chain-drive. The water cooling radiator was mounted to the nominal front of the locomotive, and a large fly wheel gave relatively smooth operation.

A second but armoured version was made to a specification defined by the Ministry of Munitions. This used an upgraded Dorman 4JO 40HP engine and two speed gearbox, coming in three versions:[1]

  • Open: armoured end plates plus height-adjustable canopy on pillars
  • Protected: as Open, plus armoured side doors and visors
  • Armoured: completely enclosed with armour-plated roof, and end slits for the driver to look through

With over 900 such locomotives supplied to the WD and MoM, post-WW1 the resultantly large and cheap supply of these trench tractors opened up the use of internal combustion engine powered locomotives to many new and existing applications, where steam engines were either too heavy, too expensive or allowed cheaper operations. The trade name Simplex was used from the early days, and in 1972 the company was renamed Simplex Mechanical Handling Ltd.[1]


Fuel Power Weight AKA Notes
Petrol 20HP Bent Frame Original trench tractor built for the War Department specification
Petrol 40HP Upgraded and armoured version of the 20HP, built for the Ministry of Munitions
Petrol 10/20HP 2ton First new post-WW1 design. 30 built between 1929-1940, latter version using Austin 12/4 engine
Diesel 18HP 4ton/5ton First diesel locomotive. First two models used the Helios 18HP made by J. & H. McLaren Ltd. of the Midland Engine Works, Leeds. Quickly replaced by the 30HP Mercedes-McLaren engine. As it cost twice as much as a similar-powered petrol engine model to purchase, most went for export
Diesel 20HP 4ton/5ton Used Dorman 2RB engine. Designation changed to 20/36HP in 1932
Petrol 25/35HP 4ton A more powerful heavy-weight locomotive built for use by contractors from 1930-1937
Diesel 65/85HP 10ton An advanced heavy-weight locomotive built in 1932, it proved unreliable and the only model produced was scrapped at the works during WW2
Diesel 25/35HP 4ton Replaced 20/36HP. Introduced 1934 when the 2RB engine was upgraded. Uses same frame and gearbox as Petrol 25/35HP, allowing later upgrade or inter change
Petrol 25/40HP One built for the Ford Motor Company at Dagenham in 1932. It used Ford AA 4-cylinder, 3-Litre side valve engine, the industrial version of the Ford Model A engine. Returned within a year, it was rebuilt and sold in 1937 to Dinmor Quarries Ltd
Petrol 25/26HP 2ton/3ton Available in 2 or 3ton variants, it replaced the 20HP from 1934 by using the more reliable Dorman 2JOR engine. Uses same frame and gearbox as the diesel-powered 20/28HP
Diesel 25/28HP 2ton/3ton Available in 2 or 3ton variants, it replaced the 20HP from 1934. Uses same frame and gearbox as the petrol-powered 20/26HP

Preserved locomotives[edit]

Many Motor Rail products survive in preservation, and they are probably the most common make of narrow gauge locomotive still in existence in the United Kingdom.

Heritage railways with Motor Rail locomotives include:

See also[edit]


  • Hall, D.R. and Rowlands J.A.S. (2001). A Guide to Simplex Narrow Gauge Locomotives. Moseley Railway Trust. ISBN 0-9540878-0-1.