155mm Gun Motor Carriage M401-3
M40: General
Date of first acceptance February 1945 Total acceptances 418
(24 converted to 8" HMC M43)
Manufacturer Pressed Steel Car Co. Crew 8 men
M40: Dimensions
Combat weight 81,000lbs
37,000kg
Height over gun mount 130"
330cm
Length without gun 280.4"
712.2cm
Gun overhang forward 68"
170cm
Width 124"
315cm
Tread 101"
257cm
Ground clearance 17"
43cm
Fire height 102"
259cm
Ground pressure, zero penetration 10.7psi
.751kg/cm²
M40: Armament
Type Mount Ammunition Traverse Elevation
155mm Gun M1A1 or M2 M13 on rear of chassis 20 rounds 36°
(18° left and right;
manual)
+45° to -5°
(manual)
M40: Armor
Assembly
Welding
Hull
Rolled and cast homogeneous steel
Location Thickness Angle from vertical
Upper front .5"
1.3cm
58°
Lower front 4.25" to 2.0"
10.8cm to 5.1cm
0° to 46°
Upper sides .5"
1.3cm
Lower sides 1.0"
2.5cm
Rear .5"
1.3cm
Top .5"
1.3cm
85°
Front floor 1.0"
2.5cm
90°
Rear floor .5"
1.3cm
90°
Gun shield .5"
1.3cm
~45°
M40: Automotive
Engine Continental R975 C4; 9 cylinder, 4 cycle, radial gasoline
Horsepower Net: 400@2400rpm
Gross: 460@2400rpm
Torque Net: 940 ft-lb@1700rpm
Gross: 1025 ft-lb@1800rpm
Fuel capacity 215gal
814L
Transmission Synchromesh, 5 speeds forward, 1 reverse
Steering Controlled differential, steering levers
Brakes Mechanical, external contracting
M40: Suspension
Type Road wheels Track return rollers
Horizontal volute spring 3 bogies/track;
2 dual wheels/bogie
2 dual/track, 3 single/track
Drive sprockets Idlers Shock absorbers
13-tooth front drive Dual adjustable at rear of track One on each bogie
M40: Track
T66
Center guide, single pin, cast, steel
Width 23"
58cm
Pitch 6"
15cm
Shoes/track 86 Ground contact length 164"
417cm
T80
Center guide, double pin, rubber and steel
Width 23"
58cm
Pitch 6"
15cm
Shoes/track 86 Ground contact length 164"
417cm
T84
Center guide, double pin, rubber
Width 23"
58cm
Pitch 6"
15cm
Shoes/track 86 Ground contact length 164"
417cm
M40: Performance
Max level road speed 21mph sustained
24mph dash
34kph sustained
39kph dash
Max trench 92"
230cm
Max grade 60% Max vertical obstacle 24"
61cm
Min turning diameter 83'
25m
Max fording depth 40"
102cm
Cruising range ~100mi, roads
~160km, roads


The hull and chassis of the M40 were based on that of the late-production medium tank M4. The hull was lengthened and widened and used HVS suspension. The drivers were provided with individual viewing cupolas. The layout of the M40 was similar to the 155mm GMC M12 in that the engine was moved forward to behind the driving compartment, the gun was mounted at the rear of the vehicle, and the M40 was open-topped except for the driving compartment.

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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. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.

  3. Siemers, Cary. "USA's Self Propelled Guns." World War II Tanks & Vehicles and Advanced Squad Leader. 4 Feb 2001. 8 Feb 2001 <http://www.shadowsfolly.com/WWII/USA/SelfPropelled.htm>.



Last updated 10 Dec 2002.

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© Copyright 2001 Chris Conners