M40 Gun Motor Carriage

T83 Prototype:
United States' T83 Gun Motor Carriage Prototype
Imperial War Museum

USA's M40 Gun Motor Carriage
Aberdeen Tank Museum

USA's M40

USA's M40

A replacement was needed for the M12 GMC (Gun Motor Carriage) as the supply of M1918 guns was exhausted and it's chassis was unsuitable for the more powerful M1 and M2 155 mm guns.1

The T83 was developed from M4 Medium tank components. It had a wider hull and used the new horizontal volute spring suspension.

On March 18, 1944, 5 pilot models of the T83 were authorized to be built. The 8" howitzer was developed after successful trials of the T83 and designated the T89.1

304 T83s and 304 T30s (cargo carriers) were ordered and production started in January 1945.1

Was the T83.1 Was standardized in May 1945.1

Used M4A3 chassis that was widened and used the high volute suspension springing (HVSS).1 The engine was moved to the front and a spade was placed in the rear to help absorb some of the recoil.1 The gun crew would stand on a hinged platform when firing the gun.1

The driver sat at the front and the engine was behind him. The driving compartment had 2 hatches in the roof for access. There was an escape hatch in the floor just behind the assistant driver.

Intended to be used well behind the front lines so no protection for the crew was provided.

Gun had range of 25,175 yards with a 95 lb round.4

Mounted 155 mm Gun M1 or M2 in a Mount M3.

A few took part in attack on Cologne (first use).

M43 Howitzer Motor Carraige:

USA's M43

Was the T89.1 Was standardized in November 1945. 576 ordered (48 finished), but was cancelled when war ended.1

Produced at Pressed Steel in Jan 1945.

Mounted 8" howitzer M1 or M2 in a Mount M17.

    M40 M43
Crew   Commander, driver, gun crew (6)2
81,2,3,4
Commander, driver, gun crew (6)2
82
Physical Characteristics      
Weight 80,020 lb 80,020 lb2, 82,000 lb3
36.6 tons1, 40.5 tons4
37,195 kg1,3
80,020 lb2
Length w/gun   29.7'4, 29' 8"3, 29' 9"2
9.04 m3
29' 9"2
Length w/o gun   20.6'4, 20' 7"2, 21' 10"1,3
6.65 m1,3
 
Height 8' 9.5" 8' 9.5"2, 9' 4"1,3, 10.8'4
2.84 m1,3
8' 9.5"2
Width 10' 4" 10.3'4, 10' 4"1,2,3
3.14 m1, 3.15 m3
10' 4"2
Width over tracks      
Ground clearance 17" 19.25"4  
Ground contact length 13' 8" 164"4  
Ground pressure   10.7 psi4 10.6 psi
Turret ring diameter      
Armament      
Main   155 mm M1A1 or M2, 155 mm M1A11
155 mm M22
155 mm3
155 mm M2, L/454
8" howitzer M1 or M2 in mount M17, 203 mm (8") M1 Howitzer1
Secondary      
MG      
Side arms 8: M1 carbines
Hand grenades
Anti-Tank grenades
   
Quantity      
Main   202,4 16
Secondary      
MG      
Side arms 960
12
10
   
Armor Thickness (mm)   122
Front: 0.5"4
Side: 0.5"4
122
Hull Front, Upper 0.5"@58°    
Hull Front, Lower 2-4.25"@0-46°    
Hull Sides, Upper 0.5@0°    
Hull Sides, Lower 1"@0°    
Hull Rear 0.5"@0°    
Hull Top 0.5@85°    
Hull Bottom 0.5-1"@90°    
Turret Front Gun shield: 0.5"@45°    
Turret Sides      
Turret Rear      
Turret Top      
Engine (Make / Model)   Continental R-975 C41
Continental R-9752
Continental3,4
Continental R-9752
Bore / stroke      
Cooling   Air4  
Cylinders   R-93,4  
Capacity      
Net HP   3953, 400@2,400 rpm4  
Power to weight ratio      
Compression ratio   5.7:14  
Transmission (Type)   Automatic4
5 forward, 1 reverse4
 
Steering   Controlled differential  
Steering ratio      
Starter   Electric4  
Electrical system   24-volt4  
Ignition   Magneto4  
Fuel (Type)   Gasoline4  
Octane      
Quantity 215 gallons 215 gallons4  
Road consumption   0.5 mpg4  
Cross country consumption      
Performance      
Traverse 18° left and right 18° left and 18° right2,4  
Max speed 24 mph 24 mph1,2,3,4
38 kph1, 38.6 kph3
24 mph2
Cross country speed 5 - 20 mph 5-20 mph2,4 5-20 mph2
Road radius 107 miles 100 miles1,3, 107 miles2,4
160 km1, 161 km3
107 miles2
Cross country radius      
Turning radius 83'    
Elevation limits +45° to -5° -5° to +45°2,4  
Fording depth 3' 6" 3'2,4, 3' 6"3
1.067 m3
3'2
Trench crossing 7' 8.5" 7.7'4, 7' 8.5"2 7' 8.5"2
Vertical obstacle 2' 10" 2' 10"2,4 2' 10"2
Climbing ability   31° (60%) slope4  
Suspension (Type) High volute suspension springing Horizontal volute spring4  
Wheels each side 6 3 bogies of 2 wheels each4  
Return rollers each side 2 24  
Tracks (Type)   Rubber block, double pin shoe4  
Length      
Width 23" 23"2,4 23"2
Diameter      
Number of links   794  
Pitch   6"4  
Tire tread      
Track centers/tread 8' 4.75" 8.4'4, 8' 4.75"2 8' 4.75"2
Production   1945: 3111
Pressed Steel Car Co.4
1945: 481

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. British and American Tanks of World War Two, The Complete Illustrated History of British, American, and Commonwealth Tanks 1933-1945, Peter Chamberlain and Chris Ellis, 1969
  3. The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
  4. Tank Data, Aberdeen Proving Grounds Series, 1968?
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