M6 Tractor

M6 High-Speed Tractor
Wartime photo of a M6 Tractor
Type	Artillery tractor
Place of origin	United States
Service history
Used by	US Army
Wars	World War II
Production history
Manufacturer	Allis-Chalmers
Produced	February 1944 – 45
Specifications
Weight	76,000 lbs / 34.5 t
Length	21 ft 6 in / 6.55 m
Width	10 ft / 3.07 m
Height	8 ft 8 in / 2.64 m
Crew	11
Main armament	.50 cal M2 machine gun
Engine	2 × Waukesha 145GZ 6-cylinder gasoline engine 2 × 190 hp at 2100 rpm (141.68 kW)
Suspension	HVSS (Horizontal Volute Spring Suspension)
Operational range	110 mi / 177 km
Speed	21 mph / 34 km/h

The M6 High-Speed Tractor was an artillery tractor manufactured by Allis-Chalmers and used by the US Army during World War II to tow heavy artillery pieces, such as the 8-inch Gun M1 and 240 mm howitzer M1. Its G-number was (G-184).

Although in the late 1930s the US Army lacked a clear mechanization policy, the success of the Blitzkrieg in 1939-40 highlighted the need of motorized vehicles for both tactical and strategic maneuver, which meant that towed artillery would need to move at a speed comparable to that of the armored fighting vehicles.

To achieve this, a series of “high speed tractors” was planned, which would tow the different artillery pieces existing (or planned) in the US Army inventory. The “high” speed was considered in comparison with horse-drawn artillery rather than that obtainable with wheeled prime movers or ballast tractors. The models considered in the series included: 7 ton, 18 ton, 13 ton, and 38 ton.

Intended to tow heavy artillery pieces as the 240 mm howitzer M1 and the 8-inch Gun M1, the M6 artillery tractor was larger and heavier than the M4 Artillery Tractor, although they had a similar layout. The main differences between both were in the following areas:

It was powered by two six-cylinder, in-line, Waukesha 145GZ gasoline engines, each of which gave 190 HP at 2,100 rev/min, with an engine displacement of 13,400 cm³. The running gear consisted on six rubber-rimmed wheels per side, with the drive wheel located at the front and a large tensioning wheel at the rear; a layout similar to the one used in the M3 light tank and later in the M4 Tractor.