Garratt

Garratt is a type of articulated steam locomotive that was designed by Herbert William Garratt. The design features two separate radial engine units, one under the front of the boiler and the other under the rear, with a large boiler and water tanks mounted on a single frame between them. This arrangement allows for a very powerful locomotive with a large boiler capacity that can negotiate sharp curves and uneven trackwork.

The first Garratt locomotive was built in 1907 by Beyer, Peacock & Company for the Great Western Railway of England. Garratt locomotives were widely adopted by railways around the world, particularly in countries with extensive narrow-gauge networks and challenging terrain, such as Australia, Africa, and South America. Their ability to carry large quantities of water and fuel, combined with their powerful tractive effort, made them suitable for long, heavy freight trains.

The unique design of the Garratt allowed for a large grate area and firebox, contributing to its high steam-raising capabilities. The two engine units are pivotally mounted, enabling the locomotive to swing through curves independently, greatly reducing the stress on the track and the locomotive itself. This articulation also allows for a longer boiler than would be possible on a rigid-framed locomotive of similar length.

Garratt locomotives were produced in a wide range of sizes and gauges, from small narrow-gauge industrial engines to large express passenger locomotives. They remained in production until the end of the steam era, with the last new Garratt being built in the early 1970s. Many Garratt locomotives have been preserved and some are still operational on heritage railways.