__NOTOC__ An unditching beam is a device that is used to aid in the recovery of

armoured fighting vehicle An armoured fighting vehicle (British English) or armored fighting vehicle (American English) (AFV) is an armed combat vehicle protected by vehicle armour, armour, generally combining operational mobility with Offensive (military), offensive a ...

s when they become bogged or "ditched". The device is a beam that is attached to the

continuous track Continuous track or tracked treads are a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the w ...

s that provides additional traction for the vehicle to extricate itself from a ditch or from boggy conditions. The unditching beam was first introduced into service during the

First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

with the British

Mark IV tank The Mark IV (pronounced ''Mark four'') was a British tank of the First World War. Introduced in 1917, it benefited from significant developments of the Mark I tank (the intervening designs being small batches used for training). The main improv ...

. It is believed the device was designed by Philip Johnson who was serving as an engineering officer at the British Army's depot at

Érin Érin () is a commune in the Pas-de-Calais department in the Hauts-de-France region in France. Situation Érin is a small village on the south side of the small river, the Ternoise which flows through St.Pol-sur-Ternoise and joins the River Ca ...

; originally the device weighed and was constructed of a solid beam of oak with two large steel plates bolted to two sides to provide protection. When not in use it was stowed on two rails mounted on the roof of the tank that ran the entire length of the vehicle, and when employed the beam was chained to the tank's tracks, giving the vehicle something firm to drive over. Unditching beams remain a commonly carried standard ancillary on a number of Russian produced armoured fighting vehicles.

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* * * * Automotive_engineering World War I military equipment of the United Kingdom {{Military-stub

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