M103 HEAVY TANK
Following contemporary American design philosophy, the M103 was built with a two-piece, cast elliptic armor scheme, similar to the M48’s design. It featured seven road wheels per side, mounted with long-arm independent torsion bars. The 28-inch (71 cm) track was shoed in steel backed rubber chevron tracks, allowing for a ground pressure of 12.9 psi. The Continental AV-1790 engine was placed at the rear of the tank, and produced a maximum output of 810 horsepower (600 kW) and 1,600 pound-feet (2,200 N⋅m) of torque, fed through a General Motors CD-850-4 two-speed transmission. This allowed the 60-ton heavy tank to achieve a maximum road speed of 21 miles per hour (34 km/h) and a maximum climbing gradient of 60%.
Initial production versions suffered a host of drivetrain mechanical problems. The Continental powerpack, shared by the much lighter M48/M60 tanks, was insufficient to drive the much heavier M103. The resulting performance of the tank was dismal; being severely underpowered and very fuel intensive. This presented a host of logistical problems for the vehicle, most prominently the extremely limited range of just 80 miles (130 km). Though this was partially corrected with the introduction of the AV-1790-2 diesel unit, it would remain cumbersome and fuel-thirsty for the majority of its service life.
For ease of production, many of the large components of the tank were made from cast armor. This design scheme was also much more mass efficient than traditional rolled plate armor. Despite being better protected than the T29-series of prototypes which preceded it, the M103 was nearly 10 tons lighter, making it competitive with the Soviet T-10/IS-8 tank. The frontal hull glacis was a compound pike, welded at the center seam, with up to 10 inches thick armor at the front. The turret was a massive single-piece cast design, fitted with heavily sloped 10-inch (254 mm) rolled-homogenous armor.
The M103 was designed to mount the 120 mm M58 gun, fitted in the M89 turret mount. Using standard Armor-Piercing Ballistic Cap Tracer Rounds, it was capable of penetrating 221-millimetre (8.7 in) of 30-degree sloped rolled-homogenous armor at 1,000 yards and 196-millimetre (7.7 in) at 2,000 yards. It could also penetrate 124-millimetre (4.9 in) 60-degree sloped rolled-homogenous armor at 1,000 yards and 114-millimetre (4.5 in) at 2,000 yards. The commander could select from 34 rounds of either M358 Armor-Piercing Ballistic Cap Tracer Rounds or M469 HEAT shells, mounted at the rear of the turret and in the hull. With both loaders, the maximum firing rate of the gun was five rounds per minute, owing to the design of the two-piece ammunition. Using the electrohydraulic turret traverse, the gunner could turn the turret at 18 degrees per second, with 15 degrees of elevation and 8 degrees of gun depression.
The armor was made from welded rolled and cast homogeneous steel of varying thickness.