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United States' M18 Gun Motor Carriage6, Hellcat6
| M18 US Ordnance Dept6 |
M18 US Ordnance Dept6 |
M18 supporting 2nd Battalion, 397th Infantry Regiment in Wiesloch, Germany on 1 April 19456 US Army6 |
M18 Aberdeen Tank Museum |
| M18 |
M18 |
M18 |
M18 |
Design
In February 1944, it was standardized as the M18 Gun Motor Carriage and nicknamed the Hellcat.1,6,7
The M18 Hellcat had three compartments: driver's, fighting, and engine.6
Driver's Compartment
The driver sat on the left and the assistant driver on the right.6 Located between them was the transmission with the shift levers on top.6 This allowed for either to shift the gears.6 Each had an accelerator pedal with the assistant driver having a lockout mechanism.6 Each had steering levers that would hang down, and the levers could be moved out of the way.6 On the left side of the driver was the instrument panel.6 There were adjustable seats for both.6 In the roof each had hinged double doors.6 These also had periscopes.6
Fighting Compartment
The turret basket contained three folding and adjustable seats.6 The commander was on the left side behind the gunner.6 The loader was located on the right side of the 76 mm gun.6
The gunner could use either a hydraulic or hand traverse control to rotate the turret.6 He also had an azimuth control.6 Periscopic and telescopic sights were used by the gunner.6
There was an auxiliary generator, located in the sub floor at the right front of the turret, that was used to recharge the batteries.6
The assistant driver had a portable fire extinguisher beside him.6
The turret bulge held the radio equipment.6
Engine Compartment
The fuel tanks were located on each side of the engine.6 The left held 75 gallons and the right 90 gallons.6
A propeller shaft went under the sub floor transmitted power from the engine to the transmission.6
The torqmatic transmission was mounted on extension rails so it could be slid out for repairs.6
There were controls inside and outside of the engine compartment that controlled its fire extinguisher.6
Starting with vehicle 1,700 it had blowers that would move hot air over the oil cooler, the battery, the engine, and to the crew.6 This equipment was sometimes installed at tank depots for earlier vehicles to winterize them.6
Main Armament
The M18 was armed with the 76 mm M1A1, M1A1C or M1A2 L/55 gun.6
The M1A1 had no muzzle brake.6 The M1A1C has threads for a muzzle brake and the barrel had rifling of one turn for each 40 calibers.6 M1A2 had threads for a muzzle brake and rifling of one turn for each 32 calibers.6
A travel lock was located in the turret for vehicles 1 - 1,857.6 This was a swinging lever with a pin.6 From vehicle 1,858 there was a spring loaded ball stud.6
Could penetrate 101 mm. Muzzle velocity 2,600 ft/sec.5 The AP shell weighed 15.4 lbs.5 It could fire a HE shell 14,000 yards.5
Prototype
On December 2, 1941, a memorandum from the G-3 to the G-4 of the General Staff recommended that a gun motor carriage be developed to carry a 37 mm M6 gun on a Christie type suspension.6 On April 1, 1942, the Ordnance Department suggested that a 57 mm M1 gun be used.6
On April 18, 1942, it was agreed to construct two prototypes that would be identified as the T49 Gun Motor Carriage.6 It was to be mobile, weigh around 12 tons, have a crew of five, reach a speed of 50 mph, armor was to be 7/8" on the turret, and 3/8" all around on the hull.6
The first prototype was tested and as a result the Tank Destroyer Command and the Ordnance Department wanted the second prototype to have a 75 mm M3 gun.6 This became the T67 Gun Motor Carriage.6 It was to have its armor increased to 1" in front.6 The side armor was reduced and the top and bottom was increased.6
The prototypes had helical coil suspensions.6 Two Buick 320 cubic inch gasoline engines produced a total of 330 HP.6
In late 1942, after the testing of a prototype at the Aberdeen Proving Ground, the Special Armored Vehicle Board recommended that the T67 have a standard engine, a 76 mm gun, and a torsion bar suspension.6 The Secretary of War approved the building of six prototypes.6 These would carry the 76 mm M1 in an open turret without a basket.6 The Continental R975-C1 engine was used.6 These prototypes were designated the T70 Gun Motor Carriage.6
Production
On January 7, 1943, without testing the T70 Gun Motor Carriage prototypes, the Army Service Forces ordered 1,000 to be constructed.6 The first first T70 was delivered in July 1943.6
- M18:
2,5073,6,7
- Manufacturer: Buick Motor Division (GMC)5
- Production: July 1943 - October 19447
- T41, T41E1 (M39): 6406
- T86: 3 prototypes6
- Manufacturer: Marmon-Herrington6
| M18 Monthly Production | |
|---|---|
| July 1943 | 66 |
| August 1943 | 836 |
| September 1943 | 1126 |
| October 1943 | 1506 |
| November 1943 | 2676 |
| December 1943 | 1946 |
| January 1944 | 2506 |
| February 1944 | 2186 |
| March 1944 | 1706 |
| April 1944 | 1506 |
| May 1944 | 1506 |
| June 1944 | 1506 |
| July 1944 | 1506 |
| August 1944 | 1506 |
| September 1944 | 1506 |
| October 1944 | 1576 |
| T41 Monthly Production | |
|---|---|
| October 1944 | 106 |
| November 1944 | 606 |
| December 1944 | 1636 |
| January 1945 | 1806 |
| February 1945 | 1806 |
| March 1945 | 1076 |
Variants
- M44 Armored Personnel Carrier: The top hatches were side hinged.6
- M44E1 Armored Personnel Carrier (T17 Command Post Vehicle): Hull raised 10".6 Hatches front hinged.6 Used during Korean War by the United States Air Force and called the Tactical Air Control Party (TACP) vehicle.6
- T9 Armored Utility Vehicle: Parts from M18 and M22.6 Had one less bogie wheel and only two support rollers.6 9.5 tons in weight.6
- T41 Armored Utility Vehicle:


The T41 was used as a prime mover for the 3" gun.6
Had a ring for a .50 cal Browning MG installed in the front. Weighed 35,000 lb. Crew 2 plus 7 passengers. Height 5' 11". - T41E1 (M39): Reconnaissance, troop carrier.6 Became the M39 in early 1945.6
- T49 Gun Motor Carriage: Prototype with 37 mm M6 gun.6

US Ordnance Dept6 - T65 Flame Tank: Converted M39.6 Carried Canadian Iroquois flame thrower.6

US Ordnance Dept - T67 Gun Motor Carriage: Prototype with 75 mm M3 gun.6

US Ordnance Dept6 - T70 Gun Motor Carriage: Prototype with 76 mm M1 gun.6 Used Torsion bar suspension.6

US Ordnance Dept6

Buick Motor Division, General Motors Corporation6

US Ordnance Dept6 - T86 Amphibious Gun Motor Carriage (Esch Device): Removed the hull plate down to the sponson line and put in a lighter amphibious hull.6 The reduction gear was lowered.6 Was to use the 21" track from M24, however the tracks weren't ready so the M18's 14" track was used.6 Propelled in water by its tracks.6 Had speed of 4.6 mph in water.6
- T86E1 Amphibious Gun Motor Carriage: Had two 26" screws to propel it in water.6 These were located in tunnels with two rudders, controlled by cables, behind them.6 Testing started in April 1944.6 Weighed 23 tons.6 Had speed of 6.2 mph in water.6 Later testing removed one screw.6
- T87 Amphibious Gun Motor Carriage: Same as T86E1 but with 105 mm howitzer.6 Was 2' 3" shorter than T86E1.6
- T88 105 mm Howitzer Motor Carriage: In August 1944, the Ordnance Department wanted to develop a vehicle with the 105 mm T12 howitzer. By December 1944, a pilot model was finished. It was identical to the M18 except for the gun and the sights. It was canceled in August 1945.
Usage
Used by tank destroyer battalions in Europe.1
It first saw action in the Summer of 1944 in Europe.1 One unit to use it quite effectively was the 630th Tank Destroyer Battalion in July 1944 reported destroying 53 Panthers & Tigers and 15 self propelled guns with only a loss of 17 of their M18s.1
Post World War II
After World War II the M18 was used by Argentina, Austria, Nationalist China, West Germany, Greece, Iran, Soviet Union, Turkey, Venezuela, and Yugoslavia.6
The M39 was supplied to the Netherlands and West Germany.6
| T49 Gun Motor Carriage6 | T67 Gun Motor Carriage6 | M18 Gun Motor Carriage6 | |
|---|---|---|---|
| Crew | Commander, driver, gun crew (3)2 Commander, loader, gunner, driver, assistant driver6 51,2,3,5,7 |
||
| Physical Characteristics | |||
| Weight | 16 tons6 | 16 tons6 | 37,557 lb3,6, 40,000 lb2,7 17.9 tons1, 19.5 tons5 17,036 kg3, 18,142 kg1, 18,160 kg7 |
| Weight - empty | 35,526 lb6 | ||
| Length w/gun | 17' 10.5"6 | 17' 10.5"6 | 21' 10"1,2,3,6,7 6.65 m3, 6.655 m7, 6.7 m1 |
| Length w/o gun | 17' 4"2, 17.5'5, 17' 10"3,7, 21' 2"6 5.436 m7, 5.44 m3 |
||
| Height | 7' 0.25"6 | 7' 0.25"6 | 8.4' (top of AA)5, 8' 5"1,2, 8' 5 7/16"6, 8' 5.44"7, 8' 5.5"3 2.5765 m7, 2.58 m3, 2.6 m1 |
| Width | 8' 9.75"6 | 8' 9.75"6 | 9.1'5, 9' 5"3,6, 9' 9"1,2,7 2.87 m3, 2.97 m1, 2.972 m7 |
| Width over tracks | |||
| Ground clearance | 14", 14.25"5,6 | ||
| Ground contact length | 9' 8", 116.5"5 | ||
| Ground pressure | 11.9 psi6 12.5 psi5 | ||
| Turret ring diameter | |||
| Armament | |||
| Main | 76 mm7 76 mm M1A12 76.2 mm (3") M1A13 3" (76 mm) M11 76 mm M1A1, L/535 76 mm M1A1 L/556 |
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| OR | 76 mm M1A1C2 76 mm M1A1C L/556 |
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| OR | 76 mm M1A22 76 mm M1A2 L/556 76.2 mm (3") M1A23 |
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| Secondary | |||
| MG | 12.7 mm (.50 cal) MG1,3,7 | ||
| MG - bow | 1: MG6 | ||
| MG - antiaircraft | .50 cal Browning MG2 .50 cal M2 Browning M1919A46 .50 cal M2 MG5 |
||
| Side arms | M3 .50 cal Tripod mount 5: M1 Carbines Grenades Smoke Pots |
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| Quantity | |||
| Main | 451,2,3,5,6,7 (HE, APC, HVAP, Canister, Smoke) | ||
| Secondary | |||
| MG | 8002,7, 8406, 1,0005 | ||
| Side arms | 450 12 4 |
||
| Armor Thickness (mm) | 72, 122 Front: 0.5"5 Side: 0.5"5 |
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| Hull Front, Upper | 0.5"6,7 12.77 |
||
| Hull Front, Lower | 12 | ||
| Hull Sides, Upper | 0.5"6,7 12.77 |
||
| Hull Sides, Lower | 12 | ||
| Hull Rear | 0.5"6,7 12.77 |
||
| Hull Top | 5/16"6 8 |
||
| Hull Bottom | 0.25"6 7 |
||
| Turret Front | 0.75"5, 1"6,7 25.47 Mantlet: 0.5"5 |
||
| Turret Sides | 0.5"5,6 12 |
||
| Turret Rear | 0.5"6 12 |
||
| Turret Top | |||
| Engine (Make / Model) | 2: Buick6 | 2: Buick6 | Continental R-975 C11,3 Continental R-9752 Continental R975C45 |
| Vehicle 1 - 1,349 | Continental R975-C16 | ||
| Vehicle 1,350 - 2,507 | Continental R974-C46 | ||
| Bore / stroke | 4 cycles5 | ||
| Cooling | Air5,6 | ||
| Cylinders | R-95, 96 | ||
| Capacity | |||
| Net HP | 3403, 4007, 400@2,400 rpm5 C1: 3406 C4: 4006 |
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| Power to weight ratio | |||
| Compression ratio | |||
| Transmission (Type) | Torqmatic5,6 3 forward 1 reverse5,6 |
||
| Steering | Controlled differential5 | ||
| Steering ratio | |||
| Starter | Electric5 | ||
| Electrical system | 24-volt5 | ||
| Ignition | Magneto5 | ||
| Fuel (Type) | Gasoline3,5 | ||
| Octane | |||
| Quantity | 165 gallons6, 169 gallons5, 170 gallons6 | ||
| Road consumption | 0.6 mpg5 | ||
| Cross country consumption | |||
| Performance | |||
| Traverse | 360°2,5, electric Hydraulic5 |
||
| Max speed | 51 mph6 | 51 mph6 | 45 mph5, 45-50 mph2, 50 mph1, 55 mph3,6,7 80 kph1, 88.5 kph3,7 |
| Cross country speed | 20 mph2 | ||
| Road radius | 105 miles3,5,6, 150 miles1,2,7 169 km3, 240 km1, 241 km7 |
||
| Cross country radius | 150 miles5 | ||
| Turning radius | 33'6 | ||
| Elevation limits | -10° to +19.5 °2 , -10° to +20°5,6 | ||
| Fording depth | 4'2,3,5,6 1.22 m3 |
||
| Trench crossing | 6' 2"2,3,6, 6.2'5 1.88 m3 |
||
| Vertical obstacle | 3'2,3,5,6 0.91 m3 |
||
| Climbing ability | 31° (60%) slope5 60%6 |
||
| Suspension (Type) | Helical spring6 | Helical spring6 | Torsion bar2,5,6 |
| Wheels each side | 56 | 56 | 55,6 |
| Return rollers each side | 26 | 26 | 45,6 |
| Tracks (Type) | T69, dry pin, steel shoe5 T69 steel6 |
||
| Length | |||
| Width | 12"6 | 12"6 | 1'5, 1' 2.38"6, 1' 2.4"2,5,7 0.3657 m7 |
| Diameter | 26"6 | ||
| Number of links | 835,6 | ||
| Pitch | 5 3/32"6 | 5 3/32"6 | 5 3/32"6, 5.25"5 |
| Tire tread | |||
| Track centers/tread | 7.9'5, 10' 10.25"2,7 3.308 m7 |
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?
- 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
- Airfix Magazine Guide #26 American Tanks of World War 2, Terry Gander and Peter Chamberlain, 1977
