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Turreted M1
Barbette M1

Convertible Medium Tank M1, turreted1-5

Turreted M1: General
Date of first acceptance 1935 Total acceptances 16
Manufacturer Rock Island Arsenal Crew
4 men:
  • Commander in turret
  • Gunner in turret
  • Driver in hull left front
  • Assistant driver in hull right front
Turreted M1: Dimensions
Combat weight 27,000lbs
12,200kg
Height 85.2" on wheels
88" on tracks
216cm on wheels
224cm on tracks
Length 193.2"
491cm
Gun overhang forward 0"
Width 98.4"
250cm
Tread 85.2"
216cm
Ground clearance 13.75" on wheels
16.25" on tracks
34.93cm on wheels
41.28cm on tracks
Ground pressure 10.6psi
.744kg/cm²
Turreted M1: Armament
Type Mount Ammunition Traverse Elevation
.50cal MG Turret 639 rounds 360°
(40° in mount,
20° left and right;
manual)
+40° to -15°
(manual)
.30cal MG Turret 2,780 rounds 360°
(40° in mount,
20° left and right;
manual)
+40° to -15°
(manual)
.30cal M2HB MG Ball mount M8 in right bow Manual Manual
Turreted M1: Armor
Maximum .625"
1.6cm
Minimum .25"
.64cm
Turreted M1: Automotive
Engine Continental R-670; 7 cylinder, 4 cycle, radial gasoline
Horsepower 268@2,400rpm Fuel capacity 41.5gal
157L
Transmission Constant mesh
Steering Controlled differential, steering levers when tracked; Gear and pinion, steering wheel when wheeled
Turreted M1: Suspension
Type Road wheels Track return rollers
Christie helical springs 4 independently sprung dual/track Flat track
Drive sprockets Idlers Shock absorbers
14-tooth rear drive At front of track None
Turreted M1: Track
Center guide, single pin, rubber bushed steel
Width 12"
30cm
Pitch 4.75"
12cm
Shoes/track 85 Ground contact length 106"
269cm
Turreted M1: Performance
Max level road speed Wheeled: 37.8mph
Tracked: 23.9mph
Wheeled: 60.8kph
Tracked: 38.5kph
Max vertical obstacle 15"
38cm
Max fording depth Tracked: 35.75"
Wheeled: 33.5"
Tracked: 90.81cm
Wheeled: 85.1cm
Radius of action Tracked: 55mi
Wheeled: 118mi
Tracked: 89km
Wheeled: 190km

The convertible medium tank M1 utilized J. Walter Christie's famous suspension design, and was able to run on either tracks or only its road wheels. When running on wheels, a chain was connected from the final drives to the rear road wheels and the tracks were stored on the vehicle's fenders. Standardization was proposed and rejected in February 1936, but was achieved when again proposed in March 1939. The tanks were declared obsolete the next March.

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Convertible Medium Tank M1, barbette2-5

Barbette M1: General
Date of first acceptance 1935 Total acceptances 3
Manufacturer Rock Island Arsenal Crew
4 men:
  • Commander in superstructure
  • Gunner in superstructure
  • Driver in hull left front
  • Assistant driver in hull right front
Barbette M1: Dimensions
Combat weight 30,000lbs
13,600kg
Height 79"
200cm
Length 193"
490cm
Gun overhang forward 0"
Width 98.4"
250cm
Tread 85.2"
216cm
Barbette M1: Armament
Type Mount
.50cal MG Barbette front
.30cal MG Barbette front, sides, rear
.30cal M2HB MG Ball mount M8 in right bow
Barbette M1: Armor
Maximum .625"
1.6cm
Minimum .25"
.64cm
Barbette M1: Automotive
Engine Continental R-670; 7 cylinder, 4 cycle, radial gasoline
Horsepower 268@2,400rpm Fuel capacity 79.5gal
301L
Transmission Constant mesh
Steering Controlled differential, steering levers when tracked; Gear and pinion, steering wheel when wheeled
Barbette M1: Suspension
Type Road wheels Track return rollers
Christie helical springs 4 independently sprung dual/track Flat track
Drive sprockets Idlers Shock absorbers
14-tooth rear drive At front of track None
Barbette M1: Track
Center guide, single pin, rubber bushed steel
Width 12"
30cm
Pitch 4.75"
12cm
Shoes/track 85 Ground contact length 106"
269cm
Barbette M1: Performance
Max level road speed Wheeled: 44mph
Tracked: 30mph
Wheeled: 71kph
Tracked: 48kph

Three convertible medium tanks M1 were built without turrets, but rather with a square barbette superstructure. Besides the .50cal and .30cal machine guns in the forward plate, a .30cal MG was fitted in each side of the superstructure and also at the rear.

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References

  1. Tank Data, vol. 1. Aberdeen Proving Ground, MD: US Army Ordnance School, July 1958.
  2. Hunnicutt, R.P. Sherman: A History of the American Medium Tank. Navato, CA: Presidio Press, 1994. Reprinted with permission from Sherman, R.P. Hunnicutt ©1994, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
  3. AGF Board No. 2. Development of Armored Vehicles, volume 1: Tanks. 1947.
  4. Sola, Samuel, Vincent Bobkowski, and Kara Crocker. Weapon Mounts for Secondary Armament. Santa Monica, CA: G. O. Noville & Associates, Inc., April 1957.
  5. Kirk, William. "Medium Tanks." TANKS! 18 Oct 2000. 11 Dec 2000 <http://mailer.fsu.edu/~akirk/tanks/UnitedStates/mediumtanks/​MediumTanks.html>. TANKS!
Last updated 10 Sep 2023.
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