M40 Gun Motor Carriage
T83 Prototype:
Imperial War Museum
Aberdeen Tank Museum
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:
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:
- 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
- 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
- The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
- Tank Data, Aberdeen Proving Grounds Series, 1968?
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