United States' M40 Gun Motor Carriage and M43 Howitzer Motor Carriage

Photos

T83 Prototype Imperial War Museum	T83 Prototype Pressed Steel Car Co.5
M40 Aberdeen Tank Museum	M40
M43

Design

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.^1,6

Used M4A3 chassis that was widened and used the high volute suspension springing (HVSS).^1,6 The engine was moved to the front and a spade was placed in the rear to help absorb some of the recoil.^1,5,6

Front Crew Compartment

The M40 had a compartment in the front that the driver sat in.⁶ Beside him was the co-driver.⁶ The M40 had an escape hatch located just behind the co-driver.⁶

The driving compartment had 2 hatches in the roof for access.

Engine

Behind the crew compartment was the engine.⁶

Armament

The M40's main armament was located in the rear of the vehicle.⁶

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

Rear Fighting Compartment

The gun crew would stand on a hinged platform when firing the gun.¹

Intended to be used well behind the front lines so no protection for the fighting compartment was provided.⁶

Prototype

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. These were built by the Pressed Steel Car Company.⁶

The 8" howitzer was developed after successful trials of the T83 and designated the T89.¹

Production

Was standardized in November 1945. 576 ordered (48 finished), but was cancelled when war ended.^1,6 304 T83s and 304 T30s (cargo carriers) were ordered and production started in January 1945.¹

• M40 Gun Motor Carriage: 311¹, 418⁶
  • Manufactured by: Pressed Steel Car Co.^4,5,6
  • Production: February 1945 - late 1945⁶
• M43 Gun Motor Carriage: 1945: 48^1,6
  • Manufactured by: Pressed Steel
  • Production: January 1945, August 1945⁶

Variants

• T30 Cargo Carrier: Designed to carry crew and ammunition.⁵
• T83 Gun Motor Carriage: Prototype for M40 Gun Motor Carriage. Had 155 mm M2 "Long Tom" gun on a widened M4A3E8 chassis.⁵
• T89 Gun Motor Carriage: Prototype for M43 Gun Motor Carriage.
• M40 Gun Motor Carriage: Mounted 155 mm Gun M1 or M2 in a Mount M3. Standardized in May 1945.¹
• M43 Howitzer Motor Carriage: Mounted 8" howitzer M1 or M2 in a Mount M17.

Usage

A few took part in attack on Cologne (first use).^5,6

Post World War II

The M40 was used in the Korean War by the United States Army.⁶

Britain

Britain bought some of the M40s and M43 and these were in service until the early 1960s.⁶

Specifications

	M40 Gun Motor Carriage	M43 Howitzer Motor Carriage
Crew	Commander, driver, gun crew (6)2,5 81,2,3,4,5,6	Commander, driver, gun crew (6)2 82
Physical Characteristics
Weight	80,020 lb2,5, 82,000 lb3 36.6 tons1, 40 tons6, 40.5 tons4 37,195 kg1,3, 40,640 kg6	80,020 lb2
Length w/gun	29.7'4, 29' 8"3, 29' 9"2,5,6 9.04 m3,6	29' 9"2
Length w/o gun	20.6'4, 20' 7"2,5, 21' 10"1,3 6.65 m1,3
Height	8' 9.5"2,5, 8' 10"6, 9' 4"1,3, 10.8'4 2.69 m6, 2.84 m1,3	8' 9.5"2
Width	10.3'4, 10' 4"1,2,3,5,6 3.14 m1, 3.15 m3,6	10' 4"2
Width over tracks
Ground clearance	19.25"4
Ground contact length	164"4
Ground pressure	10.7 psi4	10.6 psi
Turret ring diameter
Armament
Main	155 mm3 155 mm M1A11,6	8" howitzer6 8" howitzer M1 in mount M17 203 mm howitzer6 203 mm (8") M1 Howitzer1
OR	155 mm M22,5 155 mm M2, L/454	8" howitzer M2 in mount M17
Secondary
MG
Side arms
Quantity
Main	202,4,5	16
Secondary
MG
Side arms
Armor Thickness (mm)	0.47"6 122,5,6 Front: 0.5"4 Side: 0.5"4	122
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)	Continental R-975 C41 Continental R-9752,5 Continental3,4,6	Continental R-9752
Bore / stroke
Cooling	Air4
Cylinders	Radial6, R-93,4
Capacity
Net HP	3953,6, 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, Gasoline6
Octane
Quantity	215 gallons4
Road consumption	0.5 mpg4
Cross country consumption
Performance
Traverse	18° left and 18° right2,4,5
Speed - Road	24 mph1,2,3,4,5,6 38 kph1, 38.6 kph3,6	24 mph2
Speed - Cross Country	5-20 mph2,4, 20 mph5	5-20 mph2
Range - Road	100 miles1,3,6, 107 miles2,4,5 160 km1, 161 km3,6	107 miles2
Range - Cross Country
Turning radius
Elevation limits	-5° to +45°2,4,5
Fording depth	3'2,4,5, 3' 6"3 1.067 m3	3'2
Trench crossing	7.7'4, 7' 8.5"2,5	7' 8.5"2
Vertical obstacle	2' 10"2,4,5	2' 10"2
Climbing ability	31° (60%) slope4
Suspension (Type)	Horizontal volute spring4 Horizontal volute spring suspension (HVSS)5
Wheels each side	3 bogies of 2 wheels each4
Return rollers each side	24
Tracks (Type)	Rubber block, double pin shoe4
Length
Width	23"2,4,5	23"2
Diameter
Number of links	794
Pitch	6"4
Tire tread
Track centers/tread	8.4'4, 8' 4.75"2,5	8' 4.75"2