Full-track Prime Mover M331-4

M33: General
Date of first acceptance December 1943 Total acceptances 109 converted from TRV M31
Manufacturer Chester Tank Depot Crew 6 men
M33: Dimensions
Combat weight 60,000lbs
27,200kg		 Height 87"
220cm
Length 222"
564cm		 Width 107"
272cm
Tread 83"
211cm		 Ground clearance 17.125"
43.498cm
Ground pressure, zero penetration 12.3psi
.865kg/cm²
M33: Armament
Type Mount Traverse Elevation
.50cal M2HB MG Flexible in antiaircraft mount 360°
(manual)		 Manual
M33: Armor
Assembly
Riveting
Hull
Rolled homogeneous steel
Location Thickness Angle from vertical
Upper front 2.0"
5.1cm		 30°
Middle front 1.5"
3.8cm		 53°
Lower front 2.0"
5.1cm		 0° to 45°
Sides 1.5"
3.8cm		 0°
Rear 1.5"
3.8cm		 0° to 10°
Top .50"
1.3cm		 83° to 90°
Front floor 1.0"
2.5cm		 90°
Rear floor .50"
1.3cm		 90°
M33: Automotive
Engine Continental R975 C1; 9 cylinder, 4 cycle, static radial, supercharged gasoline
Horsepower Net: 350@2,400rpm
Gross: 400@2,400rpm		 Torque Net: 800 ft-lb@1,800rpm
Gross: 890 ft-lb@1,800rpm		 Fuel capacity 185gal
700L
Transmission Synchromesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M33: Suspension
Type Road wheels Track return rollers
Vertical volute spring 3 bogies/track;
2 wheels/bogie		 1 on top of each bogie
Drive sprockets Idlers Shock absorbers
13-tooth front drive Adjustable at rear of track None
M33: Track
T41
Outside guide, double pin, smooth, rubber
Width 16.0"
40.6cm		 Pitch 6"
15cm		 Shoes/track 79 Ground contact length 147"
373cm
T48
Outside guide, double pin, chevron, rubber
Width 16.56"
42.06cm		 Pitch 6"
15cm		 Shoes/track 79 Ground contact length 147"
373cm
T49
Outside guide, double pin, parallel bar, steel
Width 16.56"
42.06cm		 Pitch 6"
15cm		 Shoes/track 79 Ground contact length 147"
373cm
T51
Outside guide, double pin, smooth, rubber
Width 16.56"
42.06cm		 Pitch 6"
15cm		 Shoes/track 79 Ground contact length 147"
373cm
M33: Performance
Max level road speed 25mph
40kph		 Max trench 89"
230cm
Max grade 60% Max vertical obstacle 24"
61cm
Min turning diameter 70'
21m		 Max fording depth 42"
110cm
Cruising range ~150mi
~240km

With the 38-ton high-speed tractor M6 experiencing initial delays in production, Baldwin Locomotive converted a tank recovery vehicle M31 into a pilot prime mover by removing the turret, crane boom, winch, and armament. The Chester Tank Depot in Pennsylvania performed 109 production conversions, which were standardized as the full-track prime mover M33. These were used to tow the 8" gun and 240mm howitzer. An air compressor with outlet lines routed to the rear of the vehicle was provided to enable use of trailers with air brakes, and electrical connections for trailer stop and taillights were addded.

Top


References

  1. 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.
  2. Catalogue of Standard Ordnance Items, second edition 1944, volume I: Tank and Automotive. Washington, D.C.: Office of the Chief of Ordnance, Technical Division, 1 June 1945.
  3. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
  4. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
Last updated 11 Apr 2023.
Questions? Comments? Corrections? Email me
© Copyright 2023 Chris Conners