Shunters

Shunters, also known as switchers in the United States, are locomotives used to move rail cars within yards, assemble trains, and perform short transfers between facilities. They are designed for frequent stop-and-go work at low speeds rather than long-distance travel.

Most shunters are diesel-electric or electric. Diesel-electric shunters use a diesel engine to drive a generator that powers traction motors on the axles; electric shunters draw power from overhead catenary or a third rail. They are compact with a short wheelbase to negotiate tight curves, have high starting tractive effort, and utilize simple coupler arrangements. Many also feature multiple-unit control to allow a single operator to command several locomotives.

Uses and examples: Shunters operate in marshalling yards, container terminals, industrial railways, and mining operations. In North America the term switcher is common, while in Britain and many other regions the term shunter is standard. Notable classes include British Rail Class 08 and its derivatives, and North American models such as EMD NW2 and SW900, along with other small switcher locomotives.

History and variants: Shunters date to the early 20th century and evolved from small steam locomotives to diesel-electric and electric types for safer, more efficient yard work. Modern shunters may include remotely controlled or battery-powered variants to reduce emissions and improve performance in confined spaces.