Technical Details
A Czech hedgehog made to specifications could be constructed from any material capable of withstanding at least 60 tonnes-force (600 kN), while being at most 1.4 metres (4 ft 7 in) high. However, such parameters were hard to achieve in makeshift hedgehogs, reducing their usefulness.
The hedgehog is not supposed to be an immovable obstacle because of its size or weight. The proper size is to be slightly larger than the clearance under the enemy tank, so that a tank that attempts to move the hedgehog would instead roll on top of the hedgehog and get stuck.
Industrially manufactured Czech hedgehogs were made of three L-shaped metal brackets (L 140/140/13 mm, length 1.8 metres (5 ft 11 in), weight 198 kilograms (440 lb); later versions: length 2.1 metres (6 ft 11 in), weight 240 kilograms (530 lb)) joined by sheet metal, rivets and bolts (or, later in the war, welded together) into a characteristic spatial three-armed cross. (This pattern forms the axes of an octahedron.) Two arms of the hedgehog were connected in the factory, while the third arm was connected on-site by an M20 bolt. The arms were equipped with square "feet" to prevent sinking into the ground, as well as a notch for attaching barbed wire.
During the Normandy Invasion the allies cut up several hedgehogs and welded them to the front of M4 Sherman tanks and M5 Stuart tanks. Known as the Rhino tank, it proved very useful for clearing the hedgerows that made up the bocages across Normandy.
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