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"British Mobile Scissors-Bridge" from Tactical and Technical Trends

The following U.S. military report on British bridging tanks in WWII was originally published in Tactical and Technical Trends, No. 15, Dec. 31, 1942.

[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


Over favorable terrain, the tank is the most decisive ground weapon of modern warfare. However, it is particularly sensitive to obstacles. A relatively minor obstacle at a decisive point may so delay attacking tanks as to wholly destroy the success of the attack or result in heavy tank losses. On the other hand, one of the outstanding favorable characteristics of the tank is its battlefield mobility. In order that the tank may take full advantage of this mobility, means for the passage of obstacles which the tank cannot negotiate by itself must be made immediately available. Because of a tank unit's mobility, and the difficulty of coordination and control once the tank attack is launched, this problem of assisting tanks through obstacle areas is extremely difficult, particularly in view of the fact that the task must usually be performed in the face of hostile fire.

One possible answer to this problem has been produced by the British. They have developed and standardized a so-called scissors-bridge, for the purpose of making available to the Royal Armored Corps a tank which is capable of laying a bridge across a tank obstacle up to 30 feet in width. It has been designed so that the bridge can be laid under enemy fire with the tank completely buttoned up, thus giving the crew a maximum of protection. The bridge has been designed to take a tracked load of 30 tons.

The scissors-bridge equipment has been standardized and adapted to two types of tanks, the Covenanter (cruiser tank Mark V) and the Valentine (infantry tank Mark III), the latter being the newer design and in greater numbers. A second type of tank bridge-layer is being developed from the Churchill (infantry tank Mark IV), which will carry a one-piece 30-foot span capable of carrying a load of about 60 tons.

The construction of the scissors-bridge is shown in the accompanying sketches. Sketch 1 shows the bridge in traveling position; sketch 2, in a half-opened position.

[Sketch 1. British Scissors-Bridge--Traveling Position]

[Sketch 2. British Scissors-Bridge--Half-Opened Position]

General data on the scissors-bridge are as follows:

Length of bridge     34 ft
Overall width of bridge9 ft 6 in
Maximum tracked load carried30 tons
Power required to operate bridge30 hp (maximum)
Time required for launching2.5 min
Gear reduction from engine19 to 1
Weight of launching equipment and bridge3.5 tons
Maximum tension load on screw30 tons
Maximum load on each cable7 tons

The launching and recovering mechanism is operated by power taken from the fan drive of the tank engine, through a small oil-bath clutch and a 2-to-1 reduction gear, to a reversing gearbox directly beneath the screw feed gearbox.

The opening of the bridge begins after the launching mechanism has begun to pivot on the rollers of the launching frame. Since the cables are of fixed length, they act to open the bridge as it is pivoted about the rollers. Having been laid across the obstacle, the bridge is disengaged from the prime-mover. The bridge is then ready for the passage of other vehicles. To retrieve the bridge, the prime-mover crosses the bridge to the far side of the obstacle, hooks up to the bridge, pulls it back to the traveling position, and is then ready to proceed to the next obstacle. Safety devices have been installed on all the later models of this equipment, and are so arranged that the power is cut off automatically from the operating screw should the operator fail to disengage the clutch when the bridge is fully launched or recovered.

This equipment has given good service when operated by trained personnel. In one case 1,200 successful launchings and recoveries were made by one vehicle without undue maintenance.

The reporting officer submits the following conclusions:

This equipment is sturdy and compact, and apparently requires very little maintenance.

If enough of these vehicles could be supplied to armored units, they would afford a ready means of crossing tank barriers quickly with a maximum of protection for those laying the bridge.

Since the bridge is recovered after the crossing has been completed, a minimum of such bridging equipment can be carried within each division.

A decided disadvantage of equipment of this type is that it is a single-purpose vehicle, and unless a sufficient number are provided, they will not be available where and when needed.

When used as an organic vehicle of armored units, it should provide a flexibility of operations that would not be possible otherwise.


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