London Underground battery-electric locomotives

London Underground Battery-electric locomotives, most commonly known as battery locomotives are used for hauling engineers' trains. These locomotives are also named tunnelrats.

Main battery locomotives

Roster

Design

All locomotives were built to a similar design, but with a number of variations included over the years of development. Numbers L41-L43 had Metadyne control gear.

The locomotives have a cab at each end and are built to the standard 'Tube' loading gauge so that they can work over all lines on the London Underground network. The are equipped with standard buffers and coupling (the buffers are either hinged or retractable), 'Ward' type couplings and 'Buckeye' couplings. They have train air-brake equipment.

The body sides take the form of louvres to allow ventilation around the batteries (most locomotives had four solid body panels on one side only). All body panels are hinged to allow the batteries to be removed.

The original livery was Maroon, but this was changed to Yellow in the early 1980s.

Power

The locomotives can draw power from the 630 V electrified rails like a normal tube train, or run on 320 V DC traction batteries when the power is switched off. The lead-acid batteries are usually recharged inside a depot.

Protection

All battery locomotives are fitted with tripcocks and some (L15 - L21 & L44 - L54) are also fitted with Central Line ATP. Some locomotives (L27 - L32) are fitted with Victoria Line ATP equipment which was designed by Metronet BCV on behalf of Transplant, the operator of the fleet. This system was installed during 2007 at Ruislip Depot.fact|date=April 2008

Ownership

The locomotives are, since the start of London Underground's PPP scheme, in the ownership of TransPlant. The locomotives are usually stabled at Lillie Bridge depot or West Ruislip depot.

Use

The traditional use of these locomotives has been to haul trains as electric locomotives until they reach the area where work is to be undertaken, then (as the electrified rails would be isolated) switch to battery operation. They are also used for transporting diesel powered equipment like tampers through tunnel sections. Normally one locomotive will be at each end of the train, this allows the train to be reversed easily (the connections between different Underground lines often require reversals on route). Early locomotives were not allowed to operate on their own as they only had a single air compressor. Twin compressors were fitted after 1964.With the building of the Jubilee Line diesel-powered locomotives took over part of the jobs the battery locomotives did.

The London Underground battery locomotives have been rented to Network Rail on several occasions for trackwork in the London area.

Metronet battery locomotives

In February 2006, Metronet received four small battery locomotives. These were named "Walter", "Lou", "Anne", and "Kitty", names that pun the name of the line they were bought to work on, London Underground's Waterloo and City Line. They are used for hauling materials and equipment and were specially designed and built for work in narrow tunnels with tight curves and steep gradients. Clayton Equipment of Derby designed and built them in about four months, which is relatively fast. The locomotives weigh 15 tonnes each and have 200 Volt DC motors providing 75 hp to each axle. As a fail-safe feature they have spring-applied disc brakes that are automatically applied if something goes wrong. Built-in cameras are connected to screens in the cab to make shunting easier. Unlike London Underground's battery-electric locomotives, these battery locomotives cannot draw power from the electrified rails. Under normal use this is not a problem because they are designed to work on engineering projects in tunnels where the power is cut off anyway, but it does mean they have to return to the depot to be recharged — never far away on the relatively short W&C.