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United States' M18 Gun Motor Carriage, Hellcat

Photos

M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage
Aberdeen Tank Museum


M18 supporting 2nd Battalion, 397th Infantry Regiment in Wiesloch, Germany on 1 April 19456:
United States' M18 Gun Motor Carriage
US Army6
M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage
US Ordnance Dept6

M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage
M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage

M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage
M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage
US Ordnance Dept6

T41 Armored Utility Vehicle :
United States' T41 Armored Utility Vehicle
T41 Armored Utility Vehicle :
United States' T41 Armored Utility Vehicle
T49 Gun Motor Carriage:
United States' T49 Gun Motor Carriage
US Ordnance Dept6

T65 Flame Tank:
United States' T65 Flame Tank
US Ordnance Dept

T67 Gun Motor Carriage:
United States' T67 Gun Motor Carriage
US Ordnance Dept6

T70 Gun Motor Carriage:
United States' T70 Gun Motor Carriage
US Ordnance Dept6

T70 Gun Motor Carriage:
United States' T70 Gun Motor Carriage
Buick Motor Division, General Motors Corporation6

T70 Gun Motor Carriage:
United States' T70 Gun Motor Carriage
US Ordnance Dept6

M18 Gun Motor Carriage:
United States' M18 Gun Motor Carriage

Design

The M18 was designed from the start to be a tank destroyer and it became the fastest fully tracked vehicle used in World War II.3,7

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

The M18 Hellcat was to rely on its maneuverability to help defend against enemy vehicles.3

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 in an open turret.3,6 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 M1 could fire 16,100 yards / 14,721 m with APCBC/HE-T ammunition.8

The M1A1 had no muzzle brake.3,6 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

Tank Destroyer Armament Performance

Tank Destroyer Armament Performance

Prototype

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

In February 1944, it was standardized as the M18 Gun Motor Carriage and nicknamed the Hellcat.1,4,6

  • M18: >2,5007, 2,5073,4,6
    • Manufacturer: Buick Motor Division (GMC)5
    • Production: July 1943 - October 19443,4, ? - October 19447
      • 1943: 8126
      • 1944: 1,6956
  • T41, T41E1 (M39): 6406
    • Production:
      • 1944: 2396
      • 1945: 4676
  • T86: 3 prototypes6
    • Manufacturer: Marmon-Herrington6

Production Comparison

Tank Destroyer Production Comparison

Variants

  • 3" Gun Motor Carriage M18:
  • M39: M18 chassis without a turret used for troop or supply transportation.3
  • 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 machine gun 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
  • T65 Flame Tank: Converted M39.3,6 Carried Canadian Iroquois flame thrower.6
  • T67 Gun Motor Carriage: Prototype with 75 mm M3 gun.6
  • T70 Gun Motor Carriage: Prototype with 76 mm M1 gun.6 Used Torsion bar suspension.6
  • 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.3 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

By 1945 most of the M18s were often deployed to the regular Armored Divisions as the separate tank destroyer battalion concept was dwendling.3 They were however used as assault guns or artillery.3

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

Specifications

  T49 Gun Motor Carriage
Crew  
Physical Characteristics  
Weight 16 tons6
Weight - empty  
Length 17' 10.5"6
Height 7' 0.25"6
Width 8' 9.75"6
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure  
Turret ring diameter  
Armament  
Main  
Secondary  
MG  
MG - bow 1: MG6
MG - antiaircraft  
Side arms  
Quantity  
Main  
Secondary  
MG  
Side arms  
Armor Thickness (mm)  
Hull Front, Upper  
Hull Front, Lower  
Hull Sides, Upper  
Hull Sides, Lower  
Hull Rear  
Hull Top  
Hull Bottom  
Turret Front  
Turret Sides  
Turret Rear  
Turret Top  
Engine (Make / Model) 2: Buick6
Bore / stroke  
Cooling  
Cylinders  
Capacity  
Net HP  
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type)  
Octane  
Quantity  
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 51 mph6
Speed - Cross Country  
Range - Road  
Range - Cross Country  
Turning radius  
Elevation limits  
Fording depth  
Trench crossing  
Vertical obstacle  
Climbing ability  
Suspension (Type) Helical spring6
Wheels each side 56
Return rollers each side 26
Tracks (Type)  
Length  
Width 12"6
Diameter  
Number of links  
Pitch 5 3/32"6
Tire tread  
Track centers/tread  
  T67 Gun Motor Carriage
Crew  
Physical Characteristics  
Weight 16 tons6
Weight - empty  
Length 17' 10.5"6
Height 7' 0.25"6
Width 8' 9.75"6
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure  
Turret ring diameter  
Armament  
Main  
Secondary  
MG  
MG - bow  
MG - antiaircraft  
Side arms  
Quantity  
Main  
Secondary  
MG  
Side arms  
Armor Thickness (mm)  
Hull Front, Upper  
Hull Front, Lower  
Hull Sides, Upper  
Hull Sides, Lower  
Hull Rear  
Hull Top  
Hull Bottom  
Turret Front  
Turret Sides  
Turret Rear  
Turret Top  
Engine (Make / Model) 2: Buick6
Bore / stroke  
Cooling  
Cylinders  
Capacity  
Net HP  
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Steering  
Steering ratio  
Starter  
Electrical system  
Ignition  
Fuel (Type)  
Octane  
Quantity  
Road consumption  
Cross country consumption  
Performance  
Traverse  
Speed - Road 51 mph6
Speed - Cross Country  
Range - Road  
Range - Cross Country  
Turning radius  
Elevation limits  
Fording depth  
Trench crossing  
Vertical obstacle  
Climbing ability  
Suspension (Type) Helical spring6
Wheels each side 56
Return rollers each side 26
Tracks (Type)  
Length  
Width 12"6
Diameter  
Number of links  
Pitch 5 3/32"6
Tire tread  
Track centers/tread  
  M18 Gun Motor Carriage
Crew Commander, driver, gun crew (3)2
Commander, loader, gunner, driver, assistant driver6
51,2,3,4,5,6,7,8
Physical Characteristics  
Weight 37,557 lb3,6,7, 40,000 lb2,4
17.9 tons1,8, 19.5 tons5
17,036 kg3,7, 18,142 kg1, 18,160 kg4, 18,187 kg8
Weight - empty 35,526 lb6
Length w/gun 21' 10"1,2,3,4,6,7,8
6.65 m3,7, 6.655 m4, 6.66 m8, 6.7 m1
Length w/o gun 17' 4"2, 17.5'5, 17' 10"3,4, 21' 2"6
5.436 m4, 5.44 m3
Height 8.4' (top of AA)5, 8' 5"1,2,8, 8' 5 7/16"6, 8' 5.44"4, 8' 5.5"3,7
2.57 m8, 2.5765 m4, 2.58 m3,7, 2.6 m1
Width 9.1'5, 9' 5"3,6,7, 9' 9"1,2,4,8
2.87 m3,7, 2.97 m1,8, 2.972 m4
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 1: 76 mm4
1: 76 mm M1A12
1: 76.2 mm (3") M1A13,7
1: 3" (76 mm) M11
1: 76 mm M1A1, L/535
1: 76 mm M1A1 L/556
1: 76 mm / 2.99" M18
OR 1: 76 mm M1A1C2
1: 76 mm M1A1C L/556
OR 1: 76 mm M1A22
1: 76 mm M1A2 L/556
1: 76.2 mm (3") M1A23
Secondary  
MG 1: 12.7 mm (.50 cal) MG1,4,7
1: 12.7 mm / 0.5" MG8
MG - bow  
MG - antiaircraft 1: .50 cal Browning MG2
1: .50 cal M2 Browning M1919A46
1: .50 cal M2 MG5
1: 12.7 mm (.50 cal) MG3
Side arms M3 .50 cal Tripod mount
5: M1 Carbines
Grenades
Smoke Pots
Quantity  
Main 451,2,3,4,5,6 (HE, APC, HVAP, Canister, Smoke)
Secondary  
MG 8002,4, 8406, 1,0005
Side arms
450
12
4
Armor Thickness (mm) 72, 9 - 257, 122,8
Front: 0.5"5
Side: 0.5"5
Hull Front, Upper 0.5"4,6
12.74
Hull Front, Lower 12
Hull Sides, Upper 0.5"4,6
12.74
Hull Sides, Lower 12
Hull Rear 0.5"4,6
12.74
Hull Top 5/16"6
8
Hull Bottom 0.25"6
7
Turret Front 0.75"5, 1"4,6
25.44
Mantlet: 0.5"5
Turret Sides 0.5"5,6
12
Turret Rear 0.5"6
12
Turret Top  
Engine (Make / Model) Continental R-975 C11,3,7
Continental R-9752,8
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 Radial7, Radial 95,8, 96
Capacity  
Net HP 3403,7, 4004,8, 400@2,400 rpm5
C1: 3406
C4: 4006
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) Gasoline3,5,7
Octane  
Quantity 165 gallons6, 169 gallons5, 170 gallons6
Road consumption 0.6 mpg5
Cross country consumption  
Performance  
Traverse 360°2,3,5, electric
Hydraulic5
Speed - Road 45 mph5, 45-50 mph2, 50 mph1, 55 mph3,4,6,7,8
80 kph1, 88.5 kph3,4,7, 89 kph8
Speed - Cross Country 20 mph2
Range - Road 105 miles3,5,6,7, 150 miles1,2,4,8
169 km3,7, 240 km1, 241 km4,8
Range - Cross Country 150 miles5
Turning radius 33'6
Elevation limits -10° to +19.5 °2 , -10° to +20°5,6
Fording depth 4'2,3,5,6,7
1.22 m3,7
Trench crossing 6' 2"2,3,6,7, 6.2'5
1.88 m3,7
Vertical obstacle 3'2,3,5,6,7
0.91 m3,7
Climbing ability 31° (60%) slope5
60%6
Suspension (Type) Torsion bar2,5,6
Wheels each side 55,6
Return rollers each side 45,6
Tracks (Type) T69, dry pin, steel shoe5
T69 steel6
Length  
Width 1'5, 1' 2.38"6, 1' 2.4"2,4,5
0.3657 m4
Diameter 26"6
Number of links 835,6
Pitch 5 3/32"6, 5.25"5
Tire tread  
Track centers/tread 7.9'5, 10' 10.25"2,4
3.308 m4

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. Airfix Magazine Guide #26 American Tanks of World War 2, Terry Gander and Peter Chamberlain, 1977
  5. Tank Data, Aberdeen Proving Grounds Series, 1968?
  6. 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
  7. Armored Fighting Vehicles, 300 of the World's Greatest Military Vehicles, Philip Trewhitt, 1999
  8. World War I and II Tanks, George Forty, 2012
20th Century American Military History Crucial Site

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