Combat Car M21-3

M2: General
Date of first acceptance 1940 Total acceptances 34
Manufacturer Rock Island Arsenal Crew
4 men:
  • Commander in turret
  • Gunner in turret
  • Driver in hull left front
  • Assistant driver in hull right front
M2: Dimensions
Combat weight 25,500lbs
11,600kg
Height over AAMG mount 95"
240cm
Length 172"
437cm
Gun overhang forward 0"
Width over idler brackets 90.6"
230cm
Tread 72"
180cm
Ground clearance 14.5"
36.8cm
Fire height 75"
190cm
Turret ring diameter 47.5"
121cm
Ground pressure, zero penetration 9.4psi
.66kg/cm²
M2: Armament
Type Mount Ammunition Traverse
.50cal M2HB MG M15 in left side of turret 1364 rounds 360°
(manual)
.30cal M2HB MG M18 in right side of turret 9470 rounds 360°
(manual)
.30cal M1919A4 MG AA bracket mount M20 behind turret 360°
(manual)
.30cal M1919A4 MG Ball mount M13 in right bow Manual
M2: 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
Upper rear .375"
.953cm
Lower rear .375"
.953cm
19°
Top .375"
.953cm
90°
Floor .25"
.64cm
90°
Turret
Rolled face-hardened steel
Location Thickness Angle from vertical
Front .625"
1.6cm
30°
Sides .625"
1.6cm
Rear .625"
1.6cm
Top .25"
.64cm
90°
M2: Automotive
Engine Guiberson T-1020-4; 9 cylinder, 4 cycle, radial diesel
Horsepower Net: 220@2200rpm
Gross: 245@2200rpm
Torque Net: 580 ft-lb@1400rpm
Gross: 645 ft-lb@1300rpm
Fuel capacity 60gal
230L
Transmission Synchromesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M2: Suspension
Type Road wheels Track return rollers
Vertical volute spring 2 bogies/track;
2 wheels/bogie
3/track
Drive sprockets Idlers Shock absorbers
14-tooth front drive Trailing adjustable with volute spring at rear of track None
M2: Track
T16E1
Outside guide, double pin, rubber bushed, reversible rubber
Width 11.6"
29.5cm
Pitch 5.5"
14cm
Shoes/track 66 Ground contact length 117"
297cm
T16E2
Outside guide, double pin, rubber bushed, non-reversible rubber
Width 11.6"
29.5cm
Pitch 5.5"
14cm
Shoes/track 66 Ground contact length 117"
297cm
M2: Performance
Max level road speed 36mph
58kph
Max trench 72"
180cm
Max grade 60% Min turning diameter 42'
13m
Max fording depth 52"
130cm
Cruising range ~200mi, roads
~320km, roads

The combat car M2 was modified from the combat car M1 by the installation of a trailing idler and diesel engine. The trailing idler increased the ground contact area, which reduced the ground pressure of the combat car M2 to near that of the lighter M1. The diesel engine gave the combat car M2 a longer range than gasoline-powered tanks. Diesel-powered light tanks can be idenfitied by the long air intake pipes that travel from the air cleaners on either side of the engine compartment into the rear deck. The M2 was not fitted with a cupola, but had a folding roof like that of the combat car M1.

After the formation of the Armored Force on 10 July 1940, the combat car M2 was redesignated as light tank M1A1. The new nomenclature was approved on 22 August 1940.

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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. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
  3. Nenninger, Timothy K. "Organizational Milestones in the Development of American Armor, 1920-1940." Camp Colt to Desert Storm: The History of U.S. Armored Forces. Eds. George F. Hofmann, Donn A. Starry. USA: University Press of Kentucky, 1999.

Last updated 18 Feb 2001.
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© Copyright 2000-01 Chris Conners