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M2A1
M2A2
M2A3
M2A4

Light Tank M2A11-6

M2A1: General
Date of first acceptance 1935 Total acceptances 19
Manufacturer Rock Island Arsenal Crew
4 men:
  • Commander in turret left
  • Gunner in turret right
  • Driver in hull left front
  • Assistant driver in hull right front
M2A1: Dimensions
Combat weight 18,790lbs
8523kg		 Height over cupola roof 92"
230cm
Length 163"
414cm		 Gun overhang forward 0"
Width over side stowage 94"
240cm		 Tread 72"
180cm
Ground clearance 15"
38cm		 Fire height 72"
180cm
Turret ring diameter 44.1"
112cm		 Ground pressure, zero penetration 9.4psi
.66kg/cm²
M2A1: Armament
Type Mount Ammunition Traverse
.50cal M2HB MG M7 in turret 1800 rounds 360°
(manual)
.30cal M2HB MG Coaxial to .50cal MG 4700 rounds 360°
(manual)
.30cal M2HB MG Ball mount M8 in right bow Manual
M2A1: Armor
Assembly
Riveting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Upper front .625"
1.6cm		 17°
Middle front .625"
1.6cm		 69°
Lower front .625"
1.6cm		 21°
Sides .5"
1.3cm		 0°
Rear .25"
.64cm		 0°
Top .25"
.64cm		 90°
Floor .25"
.64cm		 90°
Turret
Rolled face-hardened steel
Location Thickness Angle from vertical
Front .625"
1.6cm		 0°
Sides .625"
1.6cm		 0°
Rear .625"
1.6cm		 0°
Top .25"
.64cm		 90°
M2A1: Automotive
Engine Continental R-670-3, -3C, -5; or W-670-7, -8; 7 cylinder, 4 cycle, static radial gasoline
Horsepower Net: R-670-3, R-670-5, W-670-7: 250@2400 rpm
R-670-3C, W-670-8: 235@2400rpm
Gross: R-670-3, R-670-5, W-670-7: 262@2400rpm
R-670-3C, W-670-8: 248@2400rpm		 Torque Net: R-670-3, R-670-5, W-670-7: 584 ft-lb@1800rpm
Gross: R-670-3, R-670-5, W-670-7: 590 ft-lb@1700rpm		 Fuel capacity 50gal
190L
Transmission Sliding, constant mesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M2A1: Suspension
Type Road wheels Track return rollers
Vertical volute spring 2 bogies/track;
2 wheels/bogie		 2/track
Drive sprockets Idlers Shock absorbers
14-tooth front drive Adjustable idler at rear of track None
M2A1: Track
T16E1
Outside guide, double pin, reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 62 Ground contact length 86"
220cm
T16E2
Outside guide, double pin, non-reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 62 Ground contact length 86"
220cm
M2A1: Performance
Max level road speed 45mph
72kph		 Max trench 48"
120cm
Max grade 60% Max vertical obstacle 24"
61cm
Min turning diameter 42'
13m		 Max fording depth 43"
110cm
Cruising range ~120mi, roads
~190km, roads

The light tank M2A1 can be differentiated from the combat car M1 by the vehicles' turrets: the light tank's was cylindrical in cross-section with an extension for the weapons, while the turret of the combat car was either D-shaped or octagonal. The light tank also had a cupola on the left rear of the turret roof. The M2A1's sliding mesh transmission was later replaced by a synchromesh model.

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Light Tank M2A21-3,5-6

M2A2: General
Date of first acceptance 1935 Total acceptances 237
Manufacturer Rock Island Arsenal Crew
4 men:
  • Commander/gunner in left turret
  • Gunner in right turret
  • Driver in hull left front
  • Assistant driver in hull right front
M2A2: Dimensions
Combat weight 19,100lbs
8660kg		 Height over cupola roof 92"
230cm
Length 163"
414cm		 Gun overhang forward 0"
Width over side stowage 94"
240cm		 Tread 72"
180cm
Ground clearance 15"
38cm		 Fire height 72"
180cm
Turret ring diameters Left turret: 35.3"
Right turret: 29.5"
Left turret: 89.7cm
Right turret: 74.9cm		 Ground pressure, zero penetration 9.6psi
.67kg/cm²
M2A2: Armament
Type Mount Ammunition Traverse
.50cal M2HB MG
--OR--
.30cal M1919A4 MG		 .50cal: M9,
.30cal: M9A1;
in left turret		 1625 rounds .50cal ~180°
(manual)
.30cal M2HB MG
--OR--
.30cal M1919A4 MG		 M2HB: ball mount M14,
M1919A4: ball mount M12;
in right turret		 4700 rounds .30cal ~180°
(manual)
.30cal M2HB MG
--OR--
.30cal M1919A4 MG		 M2HB: ball mount M8,
M1919A4: ball mounts M10 or M13;
in right bow		 Manual
M2A2: Armor
Assembly
Riveting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Upper front .625"
1.6cm		 17°
Middle front .625"
1.6cm		 69°
Lower front .625"
1.6cm		 21°
Sides .5"
1.3cm		 0°
Rear .25"
.64cm		 0°
Top .25"
.64cm		 90°
Floor .25"
.64cm		 90°
Turrets
Rolled face-hardened steel
Location Thickness Angle from vertical
Front .625"
1.6cm		 0°
Sides .625"
1.6cm		 0°
Rear .625"
1.6cm		 0°
Top .25"
.64cm		 90°
M2A2: Automotive
Engine Continental R-670-3, -3C, -5; or W-670-7, -8; 7 cylinder, 4 cycle, static radial gasoline
Horsepower Net: R-670-3, R-670-5, W-670-7: 250@2400 rpm
R-670-3C, W-670-8: 235@2400rpm
Gross: R-670-3, R-670-5, W-670-7: 262@2400rpm
R-670-3C, W-670-8: 248@2400rpm		 Torque Net: R-670-3, R-670-5, W-670-7: 584 ft-lb@1800rpm
Gross: R-670-3, R-670-5, W-670-7: 590 ft-lb@1700rpm		 Fuel capacity 50gal
190L
Transmission Sliding, constant mesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M2A2: Suspension
Type Road wheels Track return rollers
Vertical volute spring 2 bogies/track;
2 wheels/bogie		 2/track
Drive sprockets Idlers Shock absorbers
14-tooth front drive Adjustable idler at rear of track None
M2A2: Track
T16E1
Outside guide, double pin, reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 62 Ground contact length 86"
220cm
T16E2
Outside guide, double pin, non-reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 62 Ground contact length 86"
220cm
M2A2: Performance
Max level road speed 45mph
72kph		 Max trench 48"
120cm
Max grade 60% Max vertical obstacle 24"
61cm
Min turning diameter 42'
13m		 Max fording depth 43"
110cm
Cruising range ~120mi, roads
~190km, roads

The M2A2 had twin turrets placed side-by-side on the hull and was very unofficially dubbed "Mae West," since the turrets gave the tank a passing resemblance to the actress. The .50cal machine gun turret was 36" (91cm) in diameter, versus 30" (76cm) for the .30cal machine gun turret. A vision cupola was installed on the left turret for the tank commander. On early tanks the turrets were shaped like those of the light tank M2A1; that is, they were cylindrical with an extension on the front for weapon mounting. Later tanks had turrets comprised of flat vertical armor plates: seven for the smaller turret and eight for the large turret. Later tanks were also fitted with flat, rather than rounded, engine covers. The constant mesh transmission was later replaced by a synchromesh model.

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Light Tank M2A31-3,4-5,9

M2A3: General
Date of first acceptance 1938 Total acceptances 73
Manufacturer Rock Island Arsenal Crew
4 men:
  • Commander/gunner in left turret
  • Gunner in right turret
  • Driver in hull left front
  • Assistant driver in hull right front
M2A3: Dimensions
Combat weight 21,000lbs
9500kg		 Height over cupola roof 92"
230cm
Length 174.5"
443.2cm		 Gun overhang forward 0"
Width over side stowage guard rails 98"
250cm		 Tread 72"
180cm
Ground clearance 14.5"
36.8cm		 Fire height 72"
180cm
Turret ring diameters Left turret: 33.2"
Right turret: 27.3"
Left turret: 84.3cm
Right turret: 69.3cm		 Ground pressure, zero penetration 9.3psi
.65kg/cm²
M2A3: Armament
Type Mount Ammunition Traverse
.50cal M2HB MG M9 in left turret 1579 rounds ~180°
(manual)
.30cal M1919A4 MG Ball mount M12 in right turret 2730 rounds ~180°
(manual)
.30cal M1919A4 MG Ball mount M12 in right bow Manual
M2A3: Armor
Assembly
Riveting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Upper front .875"
2.2cm		 17°
Middle front .625"
1.6cm		 69°
Lower front .875"
2.2cm		 21°
Sides .625"
1.6cm		 0°
Upper rear .625"
1.6cm		 0°
Lower rear .625"
1.6cm		 19°
Top .375"
.953cm		 90°
Front floor .5"
1.3cm		 90°
Rear floor .25"
.64cm		 90°
Turrets
Rolled face-hardened steel
Location Thickness Angle from vertical
Front .875"
2.2cm		 0°
Sides .625"
1.6cm		 0°
Rear .625"
1.6cm		 0°
Top .25"
.64cm		 90°
M2A3: Automotive
Engine Continental W-670-9; 7 cylinder, 4 cycle, static radial gasoline
Horsepower Net: 250@2400rpm
Gross: 262@2400rpm		 Torque Net: 584 ft-lb@1800rpm
Gross: 590 ft-lb@1700rpm		 Fuel capacity 54gal
204L
Transmission Sliding, constant mesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M2A3: Suspension
Type Road wheels Track return rollers
Vertical volute spring 2 bogies/track;
2 wheels/bogie		 2/track
Drive sprockets Idlers Shock absorbers
14-tooth front drive Adjustable idler at rear of track None
M2A3: Track
T16E1
Outside guide, double pin, reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 67 Ground contact length 97"
246cm
T16E2
Outside guide, double pin, non-reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 67 Ground contact length 97"
246cm
M2A3: Performance
Max level road speed 36mph
58kph		 Max trench 60"
152cm
Max grade 60% Max vertical obstacle 24"
61cm
Min turning diameter 42'
13m		 Max fording depth 43"
110cm
Cruising range ~100mi, roads
~161km, roads

The distance between the bogies on the light tank M2A3 was increased, as was the distance between the turrets. This greater distance between the bogies, combined with longer stroke volute springs, improved the vehicle's ride. Also, the M2A3's rear hull was redesigned to ease engine maintenance, its gear ratios were increased, and its engine cooling was improved, among other changes. The transmissions in M2A3s were also swapped out for a synchromesh model. Eight M2A3s were built with the Guiberson T-1020-3 or T-1020-4 9-cylinder radial diesel engines, which initially made 250hp at 2,200rpm but were downrated to 220hp at 2,200rpm. These eight tanks were designated M2A3E1.

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Light Tank M2A41-8

M2A4: General
Date of first acceptance May 1940 Total acceptances 375
Manufacturers
  • American Car & Foundry Co.
  • Baldwin Locomotive Works
Crew
4 men:
  • Commander/loader in turret right
  • Gunner in turret left
  • Driver in hull left front
  • Assistant driver in hull right front
M2A4: Dimensions
Combat weight 25,600lbs
11,600kg		 Height over AAMG mount 104"
264cm
Length 174.5"
443.2cm		 Gun overhang forward 0"
Width 97.25"
247.0cm		 Tread 72"
180cm
Ground clearance 16.5"
41.9cm		 Fire height 76"
193cm
Turret ring diameter 46.75"
118.7cm		 Ground pressure, zero penetration 11.4psi
.800kg/cm²
M2A4: Armament
Type Mount Ammunition Traverse Elevation
37mm Gun M5 M20 in turret 103 rounds 360°;
20° in mount
(manual)		 +19° to -6°
(manual)
.30cal M1919A4 MG AA mount M20 behind turret 8470 rounds 360°
(manual)		 Manual
.30cal M1919A4 MG Coaxial to 37mm gun 360°;
20° in mount
(manual)		 +19° to -6°
(manual)
.30cal M1919A4 MG Ball mount in right bow Manual Manual
.30cal M1919A4 MG Fixed in each sponson None None
M2A4: Armor
Assembly
Riveting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Upper front 1.0"
2.5cm		 17°
Middle front .625"
1.6cm		 69°
Lower front 1.0"
2.5cm		 19°
Sides 1.0"
2.5cm		 0°
Upper rear 1.0"
2.5cm		 0°
Lower rear 1.0"
2.5cm		 20°
Top .25"
.64cm		 90°
Front floor .5"
1.3cm		 90°
Rear floor .25"
.64cm		 90°
Turret
Rolled face-hardened steel
Location Thickness Angle from vertical
Gun shield 1.0"
2.5cm		 0° to 14°
Front 1.0"
2.5cm		 10°
Sides 1.0"
2.5cm		 0°
Rear 1.0"
2.5cm		 0°
Top .25"
.64cm		 75° to 90°
M2A4: Automotive
Engine Continental W-670-9A; 7 cylinder, 4 cycle, static radial gasoline
Horsepower Net: 250@2400rpm
Gross: 262@2400rpm		 Torque Net: 584 ft-lb@1800rpm
Gross: 590 ft-lb@1700rpm		 Fuel capacity 54gal
204L
Transmission Synchromesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M2A4: Suspension
Type Road wheels Track return rollers
Vertical volute spring 2 bogies/track;
2 wheels/bogie		 2/track
Drive sprockets Idlers Shock absorbers
14-tooth front drive Adjustable idler at rear of track None
M2A4: Track
T16E1
Outside guide, double pin, reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 67 Ground contact length 97"
246cm
T16E2
Outside guide, double pin, non-reversible rubber
Width 11.6"
29.5cm		 Pitch 5.5"
14cm		 Shoes/track 67 Ground contact length 97"
246cm
M2A4: Performance
Max level road speed 36mph
58kph		 Max trench 60"
152cm
Max grade 60% Max vertical obstacle 24"
61cm
Min turning diameter 42'
13m		 Max fording depth 43"
110cm
Cruising range ~70mi, roads
~110km, roads

M2A4 was based on M2A3. The new tank's single flat-sided octagonal turret was fitted with a vision cupola in the left rear part of the turret. The gun mount allowed the gunner to freely elevated the coaxial weapons via a shoulder rest. The W-670-9A engine differed from the W-670-9 by the addition of an engine governor.

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References

  1. Hunnicutt, R.P. Stuart: A History of the American Light Tank, volume 1. Navato, CA: Presidio Press, 1992. Reprinted with permission from Stuart, R.P. Hunnicutt ©1992, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
  2. AGF Board No. 2. Development of Armored Vehicles, volume 1: Tanks. 1947.
  3. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
  4. Miller, David. The Illustrated Directory of Tanks of the World. Osceola, WI: MBI Publishing Co., 2000.
  5. Siemers, Cary. "USA's Light Tanks." World War II Tanks & Vehicles and Advanced Squad Leader. 25 Nov 2000. 10 Dec 2000 <http://www.shadowsfolly.com/WWII/USA/LightTanks.htm>.
  6. Kirk, William. "Light Tanks." TANKS! 21 Jun 2000. 7 Dec 2000 <http://mailer.fsu.edu/~akirk/tanks/UnitedStates/lighttanks/​LightTanks.html>. TANKS!
  7. Tank Data, vol. 2. Aberdeen Proving Ground, MD: US Army Ordnance School, Jul 1958.
  8. FM 23-80 37-mm Gun, Tank, M5 (Mounted in Tanks). Washington, DC: War Department, 25 June 1941.
  9. FM 30-40 C1 Military Intelligence Identification of United States Armored Vehicles. Washington, DC: War Department, 8 March 1942.

Last updated 18 Feb 2023.
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© Copyright 2000-23 Chris Conners