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Sherman Crab Flail Tank

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Sherman Crab flail tank

Mine clearing

In order for the Western Allies to successfully invade the beaches of Normandy, which was fortified by the German built Atlantic Wall, a great many difficulties needed to be overcome. One such hurdle was the over 5,000 mines laid by the Germans along the coast of Normandy.


The anti-tank mines were often laid in ‘minefields’, in order to block the landing and advance of the Allies. These minefields (many of them quite large) would need to be cleared and this would often need to be done under enemy fire. IWM photo shows a Sherman Crab during testing.


Crab Flail, one of Hobart’s Funnies

Prior to the invasion of Normandy, a variety of mine clearing devices had been designed and tested, with the the Sherman Crab agreed to be one of the best. It was put into production in November 1943 to equip the 79th Armoured Division, commanded by General Percy Hobart, becoming one of Hobart's Funnies. These Funnies were a group of machines and vehicles created for the special problems that were to be encountered when landing at Normandy.


The Sherman Crab used a flail system which avoided missed mines caused by bridging, a downfall of the roller types of mine clearing devices. Carrying a crew of 5, the Crab was equipped with two arms which held a rotating roller on which over 40 chains were attached. The roller was driven by the tank's engine and when engaged, caused the chains beat the ground, exploding the mines. Clearing a 9 strip feet wide, it could detonate mines up to 4 inches deep. It traveled at about 1 ¼ mph, and could explode up to 14 mines before it would need to have its chains replaced.


Sherman Crab flail tank

Marking lanes and cutting wire

The Crab was able to mark the lanes which it had swept and later versions had cutting disks on the roller which allows the tank to slice through barbed wire. It retained the Sherman 75 mm turret gun as well as the one 7.62 mm machine gun.


IWM photo shows disabled Sherman flail tank on June 6, 1944. In the center of the photograph, German prisoners await transfer to allied ships. Note the wire cutting disk at the end of the flail arm. The jeep on the right being towed to the beach is equipped with deep water wading gear. Photo source: Imperial War Museum photo.


Sherman Crab in action

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Although a very successful minesweeper, the Sherman Crab was not without problems. The crew of the tank continuously placed themselves in danger from the exploding mines and from enemy fire. The action of the chains caused vast amounts of dust which greatly limited driving and shooting visibility, and could draw the attention of the enemy.


The minesweeping procedure was to work in groups of several Crabs with some sweeping and the others to provide cover, and act as reserves. During the Normandy landings, many Crabs were able to successfully fulfill both mine-clearing and assault roles.

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