Wednesday, 26 June 2013

Lend Lease Impressions: Pershing

In 1942, the Americans received Soviet KV and T-34 tanks, which inspired the design of several American tanks. In 1945, they sent a Pershing to the Soviets, to see what they thought. From CAMD RF 38-11355-2725:

"Conclusions on testing the American heavy tank T26E3

The T26E3 is an experimental heavy (by American standards) tank, whose main combat qualities surpass those of other American tanks. However, the T26E3 does not satisfy modern requirements for a heavy tank. The main disadvantage of the T26E3 is its weak armour. Other tank weaknesses include:

1. The engine radiator, transmission lubricant radiator, differential lubricant radiator and 4 fans are in one unit, making repair of any one of these devices difficult.
2. There are many open spaces in the transmission and engine compartments. These spaces are not used for anything, nor are they necessary for maintenance.
3. The inner and outer road wheels are not loaded equally. As a result, the rubber tires on the inner road wheels wear much faster.
4. Insufficient ventilation of the fighting compartment leads to unacceptably high concentrations of CO in the fighting compartment when the gun is fired.

The T26E3 was tested on the NIBT proving grounds from May to July of this year. In total, the tank traveled 493 km. 150 km were used for training of the crew. The road condition was a dirt road, destroyed by tanks, in places covered with mud. The relatively small amount of driving on only one kind of road did not provide enough data on the reliability and performance of the tank on different terrain types.

The average speed of the tank on a dirt road is 18.9 kph, which is good for a tank that weighs 39.4 tons. This speed is achieved by:
a) a hydromechanical transmission
b) a suspension that provides very smooth travel, achieved by hydraulic shock absorbers on the road wheels.

A hydromechanical transmission also improves the ease of handling, accelerates the tank quickly, and provides good engine performance. The engine performs in a narrow range of RPM (2300-2500). The transmission input gear group provides the ability to start moving up a slope as steep as 30 degrees.

The engine temperature remained stable and within normal parameters during testing. The operational range on a dirt road is 100-115 km, which is sufficient. The driver's levers take between 25 and 35 kg of force to move, which is high.

The tank was tested on naturally occurring slopes up to 31 degrees. That appears to be the limit, at which the tank's tracks lose traction.

The armament testing showed:
1. The 90 mm gun M3 has the muzzle velocity of 810 m/s, which is higher than any known American tank gun.
2. Rate of fire when in place is equal to 6-7 rounds per minute.
3. Rate of fire when moving is 2-3 rounds per minute.

Aside from the hydromechanical transmission, other interesting features of the T26E3 include:

1. High visibility from the tank, provided by a commander's cupola with vision ports, and a large amount of periscopes mounted on the tank.
2. Connection of track links with silent-blocks.
3. Electric engine control devices.
4. Driver's seat construction.
5. Driver's compartment heating and ventilation devices.
6. Hydraulic shock absorbers on all road wheels other than the middle one.
7. Ammo rack placement at the bottom of the hull, and a conveniently placed ready rack.
8. Cooling fans directly powered by the engine."

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