M4 SHERMAN MEDIUM TANK
'THE MINE CLEARING TANK'

The mine clearing tanks that were based on the M4 Sherman tank chassis, are worth some extra pages. Not an experiment was too much to try to find the solution to come to a good mine clearing device. The most famous of these vehicles were the ‘Crab’ flailtanks. But other models also deserve to be mentioned on these pages.

When the invasion, June 6th 1944, on the beaches of Normandy were eminent, the urge to come up with a vehicle that could sweep a clear path through a minefield became important. It had to be a relative fast vehicle that had to move under enemy fire without danger to be destroyed by the mines it was clearing. When these vehicles were produced, they would be deployed with the British 79th Armoured Division.

An early sweep installation on a Matilda II in Africa

One of the first solution, and in hindsight the best, was a rotating cylinder in front of a tank with chains that were battering the ground and hopefully were striking a mine and made it detonate. The first of these contraptions were placed on Matilda and Valentine tanks. But they proved to be not a great success.

A Scorpion installation on an M3 Grant

The next generation was placed on the Grant and Sherman tank. These so called Scorpion, had two separate Dodge engines at the rear of the tank to rotate the flail. The arms of the flail were constructed beside the tank, this made it difficult to maneuver around sharp corners and small bridges. The follow up was the Pram Scorpion on the chassis of an M4 and was also driven by the engine of the Sherman. The rotor arms were bolted to the bogies and had extra support from some extra heavy rollers in front of the tracks. Experiments were also done with a model called Marquis. This had instead of a turret, an armoured housing for the engine for the rotor. None of these two types were taken into production.

The Pram Scorpion built only as a testvehicle

General Hobart went for a simple solution. A standard M4 got a flail that was directly driven by the engine of the M4. It would remain his gun, but lost the bow machinegun (the rotor was blocking the vision). To drive the rotor, an axel with a chain that was protruding on the right side of the tank. This was connected with a cardan shaft to a gearbox at the end of the flail-rotor. The flail, with 43 chains, rotated with the power of 285 hp. The whole contraption could move hydraulic up and down.

A Crab I operates in Holland

During normal driving the whole installation was lifted of the ground. When in servicemode, the whole thing was lowered, until the arms were horizontal. Disadvantage in this configuration was that in rough terrain not all of the holes could be ‘flailed’, the chains would ‘mow’ over it. To overcome this, a new arm construction was made that could follow the ground more precisely.

The Crab II with the pathmarking installation

On the left flailarm an adjustable counterweight was constructed, so the height would be always the same with the terrain. Because of this, the left hydraulic adjuster was deleted. With this model, the Crab II a pathmarker was installed at the rear on both sides of the flailtank. It consisted of a container with chalk. During ‘flailing’ a speed of 2 km/ph was driven.

Testing with the Crab was with great satisfaction, and Hobart placed them in the 79th Armoured Division for the landing in Normandy. With the 30th Tank Brigade they served until the end of the war.

A Crab II

Testing was done with the Lobster. This was equipped with an open rotor for a better view at the front. The chains were connected with a horizontal extension to create more effect. But it never came to a production because of the success of the Crab II.

A Lobster

Mine clearing with rollers

Drawing of the AMRCR

In Great-Britain the testing to find a solution to clear minefields was a constant struggle. One of these constructions was the Attachment, Anti-Mine Reconnaissance Castor Roller (AMRCR). It consisted of four heavy steel rollers at the front of a Sherman V tank. Each wheel was built up from 18 steel plates. Fourteen of those were 49.5cm wide and 25.5mm thick. The other four were 66cm across and 12.7mm thick.

How the AMRCR wheel was built up

The wheels were placed in a frame. Each wheel had an individual suspension so a maximum effect was created in the field. It was possible to dislodge the whole frame from the tank by triggering small charges, so the crew could stay in the tank and be (relative) safe. It was difficult to maneuver with construction and it was not further developed.

An 18 inch CIRD/Sherman

An installation that looked like the above Construction, with only two rollers instead of four, was the Canadian Indestructible Roller Device (CIRD). There were two versions, the (measured across the roller) 15-½ inch CIRD/Sherman (39.4cm) and the 18 inch CIRD/Sherman (45.7cm). The rollers were made out of massif steel and connected through an axel with suspension on to a frame. When a mine exploded, the complete roller shot upwards and swept forward. The frame was then lifted and the Sherman moved onwards and the roller fell back in place to ‘look’ for a next mine. The 15-½ inch CIRD had wheels with a cross section of 63.5cm and a weight of 487 kilo. The 18 inch CIRD measured 71cm and a weight of 762 kilo. During operation, the speed was around the 10 km/ph. Testing was also done with Flying Bangalore torpedo’s that were fired from the side arms. These were use to destroy barbwire obstacles and the occasional mine that came on it’s path.

The Lulu, a beauty, but not practical

A very beautiful solution with ‘rollers’ was the mine detector Lulu. Electrical coils were placed inside three lightweight wooden barrels. Two were placed on the front and one on the rear of the tank. Were the heavy rollers used with their weight to explode the mines, the Lulu detected the mine. When one was located, a light lit and a sound signal was given inside the tank. A mine demolition team was brought forward to remove the mine.

The Lulu coils together on the reardeck

It looked very impressive. When in transit, the coils were neatly stacked on the reardeck of the Sherman tank. But it was a fragile construction and slow to operate. When a mine was located, the Sherman had to back up, so the demolition team could move in. More than an experimental setup was not built.

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on the M32 Recovery Vehicle with the T1E1