were also used to carry and operate equipment such as: Churchill AVRE Bobbin: A reel of wide canvas cloth reinforced with steel poles carried in front of the tank and unrolled onto the ground to form a "path", so that following vehicles (and the deploying vehicle itself) would not sink into the soft ground of the beaches during the amphibious landing. Fascine: A bundle of wooden poles or rough brushwood lashed together with wires carried in front of the tank that could be released to fill a ditch or form a step. Metal pipes in the centre of the fascine allowed water to flow through. Small Box Girder: An assault bridge that was carried in front of the tank and could be dropped to span a gap in 30 seconds. Bullshorn Plough: A mine plough intended to excavate the ground in front of the tank, to expose and detonate any land mines. Churchill Double Onion: Two large demolition charges on a metal frame that could be placed against a concrete wall and detonated from a safe distance. The tank could place demolition charges at heights up to 12 feet. The tank was driven against a wall, the framework was lowered into the ground against the wall. The tank then backed up a 100 feet laying out an electric detonating cable. The explosives were then detonated by the tank driver. It was the successor to the single-charge device Carrot Tank. Also called the Jones Onion Tank. A large Onion frame was called the Goat Tank. ARK (Armoured Ramp Carrier): was a Churchill tank without a turret that had extendable ramps at each end; other vehicles could drive up the ramps and over the vehicle to scale obstacles, effectively functioning as a mobile bridge. Crab: A modified Sherman tank equipped with a mine flail, a rotating cylinder of weighted chains that exploded mines in the path of the tank. DD tank (from "Duplex Drive"): An amphibious M4A1 or M4A4 Sherman fitted with a large watertight canvas housing able to float and reach the shore after being launched from a landing craft up to several miles from the beach. They were intended to give support to the first waves of infantry that attacked the beaches. A Valentine tank version was used for training only. LVT "Buffalo": British name for the American LVT2 and LVT4: lightly armoured amphibious landing vehicles. The latter had a