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United States' M8 Howitzer Motor Carriage
M8 Cadillac Motor Car Division, General Motors Corporation4 |
M8 Aberdeen Tank Museum |
M8 |
M8 |
M8 |
Design
The M8's hull was completely welded except for some of the front, top, and rear, which could be removed for maintenance.
Hull
To make room for the turret the front hatches for the driver had to be moved forward.5
Engine
The M8 was powered by two Cadillac V8 engines.5
Ammunition Trailer
As the M8 only carried 46 rounds, often an ammunition trailer was fitted.5
Armament
The 75 mm gun fired a 18 lb HE shell at a muzzle velocity of 1,250'/sec.3 The .50 cal MG fired at 2,900'/sec.3
Rate of fire for howitzer was 25 rounds/minute for a range of 9,610 yards.
Prototype
The prototype model was produced by Cadillac Motor Car Division of General Motors Corp on a M5 light tank chassis.1,3
The T41 Howitzer Motor Carriage was a prototype mockup that was mounted in the center of a M5 Light Tank hull.5 The project was abandoned.5
The next prototype was the T47, and it mounted a M2 or M3 75 mm Howitzer in a turret.5 A prototype was finished in April 1942.5 The T47 was tested at Aberdeen in early 1942.1 This was accepted and became the M8.5
Production
- Total: 1,7781,5
- Manufactured by: Cadillac Motor Car Co.1 (1942)3, GMC1
- Production: September 1942 - January 19445
Variants
- T41 Howitzer Motor Carriage: Prototype.5 Howitzer mounted in center of hull.5
- T47 Howitzer Motor Carriage: Prototype.5 Howitzer mounted in turret.5
- M8 Howitzer Motor Carriage: Based on M5 chassis. Fitted with trailer hook for an ammo trailer.
- M8A1 Howitzer Motor Carriage: Used M5A1 chassis.
Usage
First use was in Italy in late 1943.1 Used in France extensively, and supplied to the Free French.1,5 Also used in the Pacific by the Marines Corps.5
Equipped HQ companies of medium tank battalions.
As the M7 became available in larger numbers the M8s were moved to reconnaissance units.5
| M8 Howitzer Motor Carriage | |
|---|---|
| Crew | 41,3,5 |
| Physical Characteristics | |
| Weight | 33,000 lb3, 36,000 lb 15.446 tons1, 15.45 tons5 15,605 kg5, 15,695 kg1 |
| Length w/gun | 14' 3"1, 14' 6"5, 14' 6.75"3 4.34 m1, 4.41 m5 |
| Length w/o gun | |
| Height | 7' 6.5"3, 7' 7"1,5 2.31 m1, 2.32 m5 |
| Width | 7' 4"5, 7' 4.25"3, 7' 5"1 2.24 m5, 2.26 m1 |
| Width over tracks | |
| Ground clearance | 6.5"3, 16.5" |
| Ground contact length | 120"3, 10' 1" |
| Ground pressure | 11.6 psi, 11.83 psi3 |
| Turret ring diameter | 54.5" |
| Armament | |
| Main | 75 mm M21 75 mm M2 howitzer5 M1A1 75 mm M2 75 mm Howitzer M33 |
| OR | M1A1 75 mm M3 |
| Secondary | |
| MG | 1: 12.7 mm (.50 cal) MG1 1: 12.7 mm Browning MG5 |
| MG - anti aircraft | 1: M2 .50 cal 1: .50 cal HBM2 MG3 |
| Side arms | .45 cal submachine gun M1 .30 Carbines Grenades |
| Quantity | |
| Main | 461,3,5 |
| Secondary | |
| MG | 4003 |
| Side arms | 600 735 8 |
| Armor Thickness (mm) | 445 (Actual thickness at horizontal) |
| Hull Front, Upper | 1.5"@0°3, 1 1/8" (2.5") |
| Hull Front, Lower | 1.75" (2.5") |
| Hull Sides, Upper | 1.125"@0°3, 1" (1 1/8") |
| Hull Sides, Lower | |
| Hull Rear | 1"@0°3 |
| Hull Top | 0.5" |
| Hull Bottom | 3/8-0.5" |
| Turret Front | 1.5"@0°3 |
| Turret Sides | 1"@0°3 |
| Turret Rear | 1" |
| Turret Top | 3/8" |
| Engine (Make / Model) | 2: Cadillac Series 421,3,5 |
| Bore / stroke | |
| Cooling | Water3 |
| Cylinders | 2 x V-83,5 |
| Capacity | |
| Net HP | 110 each5 2203 |
| Power to weight ratio | |
| Compression ratio | |
| Transmission (Type) | Hydromatic3 6 forward, 1 reverse3 |
| Steering | Controlled differential3 |
| Steering ratio | |
| Starter | |
| Electrical system | |
| Ignition | |
| Fuel (Type) | Gasoline3, Petrol5 |
| Octane | |
| Quantity | 89 gallons3 |
| Road consumption | 2 mpg3 |
| Cross country consumption | |
| Performance | |
| Traverse | 360°3 Manual3 |
| Max speed | 35 mph5, 36 mph1, 45 mph3 56 kph5, 58 kph1 |
| Cross country speed | 24 mph |
| Road radius | 100 miles1, 130 miles5, 180 miles3 161 km1, 210 km5 |
| Cross country radius | |
| Turning radius | |
| Elevation limits | +40° to -20°3 |
| Fording depth | 2' 6"3, 3' |
| Trench crossing | 5' 4", 5' 5"3 |
| Vertical obstacle | 1' 6", 2'3 |
| Climbing ability | 30° slope3 |
| Suspension (Type) | Vertical volute Vertical volute springing3 |
| Wheels each side | 4 2 double wheel bogies3 |
| Return rollers each side | 23 |
| Tracks (Type) | Steel or rubber with rubber bushed track pins3 |
| Length | |
| Width | 11 5/8"3 |
| Diameter | |
| Number of links | 673 |
| Pitch | 5.5"3 |
| Tire tread | Rubber3 |
| Track centers/tread | 6' 1.5", 73"3 |
Sources:
- The Encyclopedia of Tanks and Armored Fighting Vehicles - The Comprehensive Guide to Over 900 Armored Fighting Vehicles From 1915 to the Present Day, General Editor: Christopher F. Foss, 2002
- -
- Tank Data 2, Aberdeen Proving Grounds Series, E. J. Hoffschmidt and W. H. Tantum IV, 1969
- Profile: AFV Weapons 26: Hellcat, Long Tom and Priest and Complete Check List of all U.S. World War II Self-Propelled Weapons, Colonel Robert J. Icks, 1971
- World Encyclopedia of Armored Fighting Vehicles, Jack Livesey, 2006
