In the middle of the 1920s, American high command admitted that the M1917 tank currently used by the army was obsolete, and created a plan for the development of a superior fighting behicle. In 1924, the head of the commission was sent to Rock Island to aid in the creation of a light tank, no more than 5 tons in mass.
In cooperation with engineers from the Cunningham company (famous for its tracked tractors), the military, armed with experience of their foreign colleagues (mostly the British engineers responsible for the Medium Mk II), came to the decision that the classic tank layout is not ideal. After uniting American and foreign solutions, the T1 tank prototype was born. Tests of the chassis showed that it needs to be heavily reworked; the "tractor past" was no longer enough. The new high-tech chassis let the tank accelerate up to 29 kph, a record among similar vehicles. Sadly, this could not be repeated in combat conditions, as the chassis performed poorly on cross-country terrain, bomb craters, etc.
The chassis consisted of 16 small diameter wheels, 8 per side, with spring amortization, 6 supporting rollers, a front idler wheel, and a rear drive wheel. The tank hull was made of partially welded and partially bolted together armour plates 10-15mm thick. The transmission and 8 cylinder gasoline engine were in the front. The engine was capable of 132 hp at 2600 RPM. The tank had a 58.5 gallon (221.5 liter) gas tank, and a 4 speed gearbox. The engine was started electrically. The driver's compartment was united with the fighting compartment, in the back of the tank. The T1's crew consisted of two members: the driver and commander (who doubled as a gunner).
Armament was installed in the turret only. It consisted of a 37 L/50 M5 37mm gun, with 104 shells (some sources claim 80), and a coaxial M1919A4 Browining machine gun (with 3000 rounds). Despite the small caliber of the main gun, the muzzle velocity of 777 m/s allowed it to penetrate any currently fielded armour at 1000 m.
The T1 light tank was worked on through 1926, and a prototype was handed to the military in early 1927. Field tests were disappointing. The prototype had poor mobility, could barely cross a trench two meters across, and the stiff suspension made firing on the move difficult. After modifications, the T1E1 was accepted by the military in 1928, as the M1. 4 tanks were sent to the 4th Tank Company (Fort Meade, Maryland), where they tested extensively through 1930. After these tests, the T1E2 modification was equipped with a more powerful engine, a modified turret (without a slanted armour plate) and thicker front armour. The tank was later equipped with a longer 37mm gun.
The last modification was the T1E3, with a spring suspension and a long barreled gun. Nevertheless, due to many design drawbacks, mass production of the T1 light tanks never got off the ground. The only known T1E1 is displayed at the Aberdeen tank museum.
Original article available here.