Unditching roller

The unditching roller is a device fitted to the front of military vehicles, such as the M3 Scout Car and the M3 Half-track, for the purpose of preventing the vehicle from getting stuck in an obstacle, such as a ditch.

Upon entering a ditch the roller prevents the front of the vehicle digging-in to the opposite face of the ditch, instead the roller acting as a wide wheel enabling the front to climb out of the ditch more easily.

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Wikipedia