M8 Howitzer Motor Carriage

USA's M8 Howitzer Motor Carriage
Aberdeen Tank Museum

USA's M8

USA's M8

USA's M8

The prototype model was produced by Cadillac Motor Car Division of General Motors Corp on a M5 light tank chassis.1,3 The T-47 was tested at Aberdeen in early 1942.1

Hull was completely welded except for some of the front, top, and rear, which can be removed for maintenance.

Equipped HQ companies of medium tank battalions.

First use was in Italy in late 1943.1 Used in France extensively, and supplied to the Free French.1 Also used in the Pacific.

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

M8:

Based on M5 chassis. Fitted with trailer hook for an ammo trailer.

M8A1:

Used M5A1 chassis.

Rate of fire for howitzer was 25 rounds/minute. Muzzle velocity of 1,250 ft/sec, range 9,610 yards

  M8 Howitzer Motor Carriage
Crew Commander, gunner, driver, co-driver2
41,2,3
Physical Characteristics  
Weight 33,000 lb3, 36,000 lb
15.446 tons1, 16.4 tons2
15,695 kg1
Length w/gun 14' 3"1, 14' 6.75"3
4.34 m1,2
Length w/o gun  
Height 7' 6.5"3, 7' 7"1
2.29 m2, 2.31 m1
Width 7' 4.25"3, 7' 5"1
2.24 m2, 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 or M3 howitzer2
M1A1 75 mm M2 or M3
75 mm Howitzer M33
Secondary  
MG 12.7 mm (.50 cal) MG1
.50 cal MG, AA2
M2 .50 cal AA
.50 cal HBM2 MG, AA3
Side arms .45 cal submachine gun
M1 .30 Carbines
Grenades
Quantity  
Main 461,2,3
Secondary  
MG 4003
Side arms 600
735
8
Armor Thickness (mm) (Actual thickness at horizontal)
Front: 302
Side: 252
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
Bore / stroke  
Cooling Water3
Cylinders 2 x V-83
Capacity  
Net HP 2202,3
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
Octane  
Quantity 89 gallons3
Road consumption 2 mpg3
Cross country consumption  
Performance  
Traverse 360°3
Manual3
Max speed 36 mph1, 45 mph3
58 kph1, 60 kph2
Cross country speed 24 mph
Road radius 100 miles1, 180 miles3
161 km1
Cross country radius  
Turning radius  
Elevation limits +40° to -20°2,3
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
Production Cadillac Motor Car Division, GMC 9/1942-1/1944: 1,7781
1942: Cadillac Motor Car Co.3

Sources:

  1. 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
  2. Jane's World War II Tanks and Fighting Vehicles The Complete Guide, Leland Ness, 2002
  3. Tank Data 2, Aberdeen Proving Grounds Series, E. J. Hoffschmidt and W. H. Tantum IV, 1969
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