Twin 40mm Self-propelled Gun M421-8

M42: General
Date of first acceptance August 1951 Total acceptances ~3,700 M42 and M42A1
Manufacturers
  • Cadillac Motor Car Division of General Motors Corp.
  • ACF Industries, Inc.
Crew
6 men:
  • Commander in hull right front
  • Gunner in turret left
  • Sight setter in turret right
  • Two loaders in turret rear
  • Driver in hull left front
M42: Dimensions
Combat weight 49,800lbs
22,600kg		 Height over gun shield 112.1"
284.7cm
Length without gun 229.1"
581.9cm		 Gun overhang forward 21.2"
53.8cm
Width over fenders 126.9"
322.3cm		 Tread 102.5"
260.4cm
Ground clearance 17.3"
43.9cm		 Fire height 82.5"
210cm
Ground pressure, zero penetration 9.3psi
.65kg/cm²
M42: Armament
Type Mount Ammunition Traverse Max traverse rate Elevation Max elevation rate
40mm Dual Automatic Gun M2A1 M4E1 in turret 480 rounds 360°
(manual and hydraulic)		 40°/sec +87° to -5°
(manual)
+85° to -3°
(hydraulic)		 25°/sec
.30cal M1919A4 MG Flexible on front or rear of gun mount 1,750 rounds 360°
(manual)		 -- Manual --
Aiming equipment
Computing sight M38 with reflex sight M24C
Night vision
Infrared periscope M19 for driver
M42: Armor
Assembly
Welding
Hull
Rolled and cast homogeneous steel
Location Thickness Angle from vertical
Upper front .5"
1.3cm		 33°
Lower front 1.0"
2.5cm		 39°
Upper sides .5"
1.3cm		 0°
Lower left front side .5"
1.3cm		 45°
Lower sides .5"
1.3cm		 60°
Upper rear .5"
1.3cm		 56°
Lower rear .75"
1.9cm		 41°
Top .5"
1.3cm		 90°
Front floor 1.25"
3.18cm		 90°
Rear floor .375"
.953cm		 90°
Turret
Rolled homogeneous steel
Location Thickness Angle from vertical
Gun shield .5"
1.3cm		 0° to 47°
Sides .3"
.8cm		 0°
Rear .3"
.8cm		 0°
Top Open
M42: Automotive
Engine Continental AOS-895-3; 6 cylinder, 4 cycle, opposed, supercharged gasoline
Horsepower Net: 446@2,400rpm
Gross: 500@2,800rpm		 Torque Net: 890 ft-lb@2,200rpm
Gross: 955 ft-lb@2,400rpm		 Fuel capacity 140gal
530L
Transmission Allison CD-500-3, 2 ranges forward, 1 reverse
Steering Mechanical, T-bar
Brakes Multiple disc
M42: Suspension
Type Road wheels Track return rollers
Torsion bar 5 individually sprung dual/track 3 dual/track
Drive sprockets Idlers Shock absorbers
12-tooth rear drive Dual compensating at front of track On first 2 and last road wheels/track
M42: Track
T91E3
Center guide, single pin, steel with detachable rubber pad
Width 21"
53cm		 Pitch 6"
15cm		 Shoes/track 75 Ground contact length 127"
323cm
M42: Performance
Max level road speed 45mph
72kph		 Max trench 72"
180cm
Max grade 60% Max vertical obstacle 28"
71cm
Min turning diameter Pivot Max fording depth 48"
120cm
Cruising range ~100mi, roads
~160km, roads

The M42 Duster was based on the 76mm gun tank M41, and retained the rear-engine and rear-drive layout. The twin 40mm guns were mounted in an open turret slightly ahead of the hull centerline. The hull featured a large door in the front and two roof hatches ahead of the turret. Early M42s had conical flash hiders on the 40mm guns, but these were replaced by three-pronged flash suppressors later in production. A reinforcing ring was added to the three-prong suppressors after their introduction. Early Dusters also lacked a muffler for the auxiliary generator engine. One was placed on the front of the right-hand pioneer tool stowage rack, but later in the production run a larger muffler was used. The hull roof between the driver and vehicle commander was formed by front- and rear-opening doors on early vehicles, but these were later eliminated. The vehicle could be crewed by 5 men, in which case the commander would also act as sight setter.

The fuel-injected AOSI-895-5 engine of the 76mm gun tanks M41A2 and M41A3 was installed in the M42 when the kits became available, changing the designation to M42A1. The fuel injection system increased the M42A1's road range to around 120mi (190km).

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References

  1. Hunnicutt, R.P. Sheridan: A History of the American Light Tank, volume 2. Navato, CA: Presidio Press, 1995. Reprinted with permission from Sheridan, R.P. Hunnicutt ©1995, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.
  2. TM 9-761A Self-propelled Twin 40-mm Gun T141. Washington, DC: Department of the Army, 8 May 1952.
  3. TM 9-7218 Twin 40-mm Full Tracked Self-propelled Gun M42 (T141). Washington, DC: Department of the Army, 21 May 1957.
  4. FM 44-61 Self-propelled Twin 40-mm Gun T141. Washington, DC: Department of the Army, 6 April 1953.
  5. FM 44-61 Procedures and Drills for Twin 40-mm Self-propelled Gun M42 and M42A1. Washington, DC: Headquarters, Department of the Army, 25 January 1968.
  6. FM 44-2 Air Defense Artillery Employment Automatic Weapons M42/M55. Washington, DC: Headquarters, Department of the Army, 1 November 1968.
  7. TM 9-500 C3 Data Sheets for Ordnance Type Materiel. Washington, DC: Headquarters, Department of the Army, 12 October 1966.
  8. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
Last updated 31 Aug 2024.
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