Departmental locomotives on the London Underground consist of vehicles of a number of types which are used for engineering purposes.

The London Underground has also owned several departmental self-powered vehicles designed for other duties.

Three Plasser & Theurer track tamping machines were purchased in 1980, and two Unimog road-rail vehicles were obtained in 1983 and 1986, for use as depot shunters.

When the Central London Railway opened in 1900, it used camel-back electric locomotives hauling six-car trains.

The locomotives weighed 44 tons and were largely unsprung, causing severe vibration problems in properties near the line.

In an effort to resolve the problem, four of the coaches were fitted with motors, in the first trial in Britain of the Sprague-Thomson-Houston multiple unit control system.

[4] During the Second World War they were used as pilot motor cars for refreshment trains on the Piccadilly line, which supplied food to people sleeping on the stations to escape from the bombing of the city.

The final one was stored in 1955, in the hope that it would be restored and preserved, but by 1960, the project appeared to be too costly, and so the gate end of the car was cut off, and the rest of it was scrapped.

[6] The 14 departmental vehicles which were operational in 1934 continued to be used until 1953, by which time their age made maintenance very difficult.

Following withdrawal, L137 was shipped to the Isle of Wight, to replace a car on the Island Line which had been damaged.

This resulted in a large number of spare cars, which were transferred to Ruislip Depot for eventual scrapping.

The pilot motor cars carried large stencils at both ends, so that they would not accidentally be scrapped until their duties were complete.

One advantage of the ballast motor cars over battery locomotives was that the interiors could be used by personnel and for storing small tools, although they were less powerful, and could only work when the traction current was switched on.

The conversion was carried out at British Rail Engineering Limited's Derby Litchurch Lane Works.

Two units were fitted with Automatic Train Protection (ATP) equipment to allow them to work on the Central line, two were based at Ruislip Depot, and two were owned by TransPlant.

The units were not renumbered in the engineering series and continued to carry their passenger fleet numbers.

Between 1935 and 1950, the District line had a weed-killing train, initially consisting of a 1905-built B stock driving motor car and a control trailer.

The middle vehicle of the five contains a fan unit, which supplies large volumes of low pressure air to a series of nozzles, which disturb the dust on the tunnel walls and track.

The cars on either side of it draw the dust-laden air into filter chambers, and are fitted with conveyors for discharging the dust at depots.

[21] They previously owned a Unimog tractor-trailer pair of vehicles, purchased in 1982, which were used for leaf-clearing duties.

Nozzles on the tractor unit were used to suck up the leaves, which were then stored in a 570-cubic-foot (16 m3) bin mounted in the trailer.

[11] Since 2002, a diesel-powered rail grinding unit owned by Schweerbau GmbH & Co. KG has been hired for track maintenance purposes.