Switcher locomotive

This article is about the locomotive. For other uses, see Switcher (disambiguation).

A modern US switcher, an EMD MP15DC

British Rail Class 08 — a typical smaller European shunter

A switcher or shunter (Great Britain: shunter; Australia: shunter or yard pilot; USA: switcher or switch engine, except Pennsylvania Railroad: shifter) is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been brought in, and generally moving railroad cars around – a process usually known as switching (UK: shunting). They do this in classification yards (Great Britain: marshalling yards). Switchers may also make short transfer runs and even be the only motive power on branch lines and switching and terminal railroads.

The typical switcher is optimised for its job, being relatively low-powered but with a high starting tractive effort for getting heavy cars rolling quickly. Switchers are geared to produce high torque but are restricted to low top speeds and have small diameter driving wheels. Switchers are rail analogs to tugboats.

Switching is hard work, and heavily used switch engines wear out quickly from the abuse of constant hard contacts with cars and frequent starting and stopping.

Power types

Diesel

File:Lowslug.jpg

An EMD SD39 and slug in switching service

Diesel switchers tend to have a high cab and often lower and/or narrower hoods (bonnets) containing the diesel engines, for all round visibility. Slugs are often used because they allow even greater tractive effort to be applied. Nearly all slugs used for switching are of the low hood, cabless variety. Good visibility in both directions is critical, because a switcher may be running in either direction; turning the locomotive is time-consuming. Some earlier diesel switchers used cow-calf configurations of two powered units in order to provide greater power.

Electric

Light dual-mode (electric and diesel) shunter SBB Tem 346

The vast majority of modern switchers are diesels, but countries with near-total electrification, like Switzerland, use electric switchers. Small industrial shunters are sometimes of the battery-electric type. An early battery-electric shunting locomotive is shown here. Flywheel energy storage was also used experimentally by Sentinel.

Three power

The "GE three-power boxcab locomotive" was a type of switcher developed in the USA in the 1920s. It was a diesel-electric locomotive which could alternatively run on batteries (for use inside warehouses) or from a third rail or overhead supply. It was a type of electro-diesel locomotive.

Steam

Steam shunter/switchers are now mainly of historical interest. Steam switchers were either tank locomotives or had special (smaller) tenders, with narrow coal bunkers and/or sloped tender decks to increase rearward visibility. Headlights, where carried, were mounted on both ends.

Small industrial shunters have sometimes been fireless locomotives and a few of these are still at work in Germany.

Non-US shunters

TCDD DH33121 shunter in Istanbul, Turkey. February 24, 2008

British and European locomotives of this type tend to be much smaller than the common size in the United States. Current British shunters are 0-6-0 diesel-electrics, Class 08 and Class 09, of 350-400 horsepower. These were developed from similar locomotives supplied by the English Electric Company to the Big Four British railway companies in the 1930s and 1940s, e.g. those pioneered by the LMS. Similar locomotives were exported to the Netherlands (e.g. NS Class 600) and Australia (e.g. Victorian Railways F class (diesel)).

In continental Europe 0-6-0 diesel-hydraulics, similar to the short-lived British Rail Class 14, are widely used. Two examples on the Turkish State Railways are TCDD DH33100 and TCDD DH7000.

Station pilot

A station pilot is a shunting engine based at a major passenger station, used for moving trains or carriages between platforms, assembling trains, and other passenger train shunting tasks. Having assembled a train, it could also be used to assist the train engine in starting a train by pushing from behind. It is a predominantly British term.

Station pilots have recently been phased out in the UK as the majority of passenger trains are formed with multiple units or have a Driving Van Trailer at the opposite end to the locomotive; the few locomotive-hauled passenger trains are shunted by the train engine rather than a dedicated station pilot.

Gallery

• 
  Diesel shunter ChME-3ME 6750 at Vilnius station, Lithuania
• 
  RailPower Railpower GG20B Green Goat
• 
  Wabtec EMD GP20D Switcher

See also

• Hydrail switcher
• Road switcher
• Rail car mover - some of which resemble HiRail trucks
• Road-rail vehicle
• Tugboat, marine analog
• Unimog