M4 Tractor

M4 Tractor, High Speed, 18 tons
M4 high speed tractor with 90-mm ammo box
Type	Artillery tractor
Place of origin	United States
Service history
In service	1943–1960
Used by	US Army Belgian Army
Wars	World War II
Production history
Designed	1942
Manufacturer	Allis-Chalmers
Produced	March 1943 – June 1945
No. built	5,552
Variants	Anti-aircraft and howitzer towing variants
Specifications
Weight	31,400 lb (14.2 t)
Length	210 in (5.33 m)
Width	97 in (2.46 m)
Height	99 in (2.51 m)
Crew	1 + 11
Main armament	M2 Browning machine gun
Engine	Waukesha 145GZ OHV I6 gasoline engine 210 hp (156 kW)
Power/weight	14.70 hp/t
Suspension	Vertical volute spring
Operational range	100 mi (160 km)
Speed	35 mph (56 km/h)

The M4 High-Speed Tractor was an artillery tractor used by the US Army from 1943.

The M4 was based on the chassis and drive train of the obsolescent M3 Light Tank which introduced the trailing idler. This common practice of re-using old vehicles simplified design, allowed for easy production, and made maintenance in the field easier.

One variant was designed to tow anti-aircraft guns and another for howitzers. The rear compartment carried the gun crew and other equipment and some later variants included a crane to assist with heavier projectiles.

Two types of ammunition boxes were used on all models: a 90 mm box with side "tailgates" to access 90 mm shells pigeon-holed in the sides, and a combination box for 155mm / 8-inch / 240 mm ammunition with a rear tailgate, and hoist.

The M4 was manufactured by Allis-Chalmers of Milwaukee, starting in 1942 and was in U.S. military service until approximately 1960. Under the Mutual Defense Assistance Program, the M4 was supplied to Greece, The Netherlands, Japan, Brazil, Yugoslavia and Pakistan after World War II ended. In the Indo-Pakistani War of 1965 the Pakistani Army used the M-4 Tractor to haul M115 Howitzers to the battlefield of Chamb and then to the Lahore front.

After the war many types of these tractors were stripped of their military components and used for log skidders and power line construction. Many were used as carriers for rock drills, used in logging road construction in British Columbia. The first prototype was designed in the early 1960s by G.M. Philpott Ltd. of Vancouver, BC, and Scott-Douglas Industries, who supplied the M4 Carrier. It was used by MacMillan, Bloedel, and Powell River Company at their Juskatla, BC logging operation. Many improvements were made and when Finning Tractor later bought G.M. Philpott, the machine became the Finning Tank Drill. At least 500 were built, many of which are still in service. The original Finning Tank Drill was replaced by the M32F and M40F Tank Drills, which used larger Sherman tank carriers. At Amsterdam Airport Schiphol in the Netherlands, at least two refurbished M4s were used by the airport fire brigade in the 1960s and '70s.