High Speed Tractor M8A11-9

M8A1: General
Date of first acceptance 1950 Total acceptances 480
Manufacturer Allis-Chalmers Manufacturing Company Crew
2 men:
  • Driver in hull left front
  • Assistant driver in hull right front
M8A1: Dimensions
Weight with fuel and stowage, without crew or load 42,250lbs
19,160kg		 Height overall 122-11/16"
311.6263cm
Length overall 265⅛"
673.418cm		 Width overall 130½"
331.5cm
Tread 102½"
260.4cm		 Ground clearance 19-5/16"
49.0538cm
Ground pressure without crew or load 5.7psi
.40kg/cm²
M8A1: Armament
Type Mount Ammunition Traverse
.50cal M2HB MG Flexible in ring mount M68 525 rounds 360°
(manual)
M8A1: Armor
None
M8A1: Automotive
Engine Continental AOS-895-3; 6 cylinder, 4 cycle, opposed, supercharged gasoline
Horsepower Net: 363@2,800rpm
Gross: 500@2,800rpm		 Torque Net: 760 ft-lb@2,060rpm
Gross: 985 ft-lb@2,300rpm		 Fuel capacity 225gal
852L
Transmission Allison CD-500-3, 2 ranges forward, 1 reverse
Steering Mechanical, T-bar
Brakes Multiple disc
M8A1: Suspension
Type Road wheels Track return rollers
Torsion bar 6 individually sprung dual/track 4 dual/track
Drive sprockets Idlers Shock absorbers
12-tooth front drive Dual adjustable at rear of track On first 2 and last road wheels/track
M8A1: Track
T91E3
Center guide, single pin, steel with detachable rubber pad
Width 21"
53cm		 Pitch 6"
15cm		 Shoes/track 87 Ground contact length 157⅛"
399.098cm
M8A1: Performance
Max level road speed 40.2mph
64.7kph		 Max trench 84"
210cm
Max grade 60% Max vertical obstacle 30"
76cm
Min turning diameter Pivot Max fording depth 42"
110cm
Cruising range ~180mi, roads
~290km, roads

Development of the high speed tractor T42 began in early 1945, and it used the same powertrain and suspension as the armored utility vehicle M44. With a specified platform payload capacity of 15,000lb (6,800kg), it was to tow loads of 18,000-32,000lb (8,200-14,500kg). Six T42s were assembled, and in December 1945 these were standardized as the cargo tractor M8. The M8 was 259" (658cm) long, 123" (312cm) wide, 119" (302cm) tall, and weighed 37,000lb (16,800kg) empty. Maximum speed was 35mph (56kph), maximum fording depth was 40" (100cm), and maximum range was 150 miles (240km) on its 225 gallons (852L) of gasoline.

As work progressed on prototypes of what would become the 76mm gun tank M41, the AOS-895-3 engine and CD-500-3 transmission replaced the powertrain in the M8, and this vehicle was standardized as the M8A1. The towing and platform payload capacities remained the same as those of the M8. When the AOSI-895-5 fuel injected engine of the M41A2 and M41A3 tanks was migrated into the M8A1, the vehicle was redesignated as the M8A2. Allis-Chalmers manufactured 480 M8A2s in addition to the 480 M8A1s assembled.

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References

  1. TM 9-7420 Operation and Organizational Maintenance Cargo Tractor M8E2. Washington, DC: Department of the Army, January 1955.
  2. Hunnicutt, R.P. Bradley: A History of American Fighting and Support Vehicles. Novato, CA: Presidio Press, 1999. Reprinted with permission from Bradley, R.P. Hunnicutt ©1999, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
  3. TM 9-500 C3 Data Sheets for Ordnance Type Materiel. Washington, DC: Headquarters, Department of the Army, 12 October 1966.
  4. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
  5. TM 9-2430-200-20P Organizational Maintenance Repair Parts and Special Tools List for Tractor, Full Tracked, High Speed: M8A1 (2430-740-5800) and Tractor, Full Tracked, High Speed: M8A2 (2430-563-7250). Washington, D.C.: Headquarters, Department of the Army, 10 December 1959.
  6. ORD 9 SNL G-252 List of All Service Parts of Tractor, Full Tracked, High Speed: M8A1. Washington, DC: Department of the Army, 27 September 1955.
  7. Standard Military Vehicle Characteristic Data Sheets. Center Line, MI: Army Tank and Automotive Command Research & Engineering Directorate, July 1960.
  8. TM 9-2800-1/TO 19-75A-89 Military Vehicles (Ordnance Corps Responsibility). Washington, DC: Departments of the Army and Air Force, 13 February 1953.
  9. Sola, Samuel, Vincent Bobkowski, and Kara Crocker. Weapon Mounts for Secondary Armament. Santa Monica, CA: G. O. Noville & Associates, Inc., April 1957.
Last updated 30 Jul 2024.
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