An unditching beam is a device that is used to aid in the recovery of armoured fighting vehicles when they become bogged or "ditched".
The device is a beam that is attached to the continuous tracks 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 with the British Mark IV tank.
[1] 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; originally the device weighed one-half long ton (0.51 t) and was constructed of a solid beam of oak with two large steel plates bolted to two sides to provide protection.
[2][3] Unditching beams remain a commonly carried standard ancillary on a number of Russian produced armoured fighting vehicles.