Twin 40mm Self-propelled Gun M421-2
M42: General
Date of first acceptance August 1951 Total acceptances ~3700 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 1750 rounds 360°
(manual)
-- Manual --
Night vision
Infrared periscope M19 for driver
Rangefinder
Computing sight M38 with reflex sight M24C
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
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
Rear .3"
.8cm
Top Open
M42: Automotive
Engine Continental AOS-895-3; 6 cylinder, 4 cycle, opposed, supercharged gasoline
Horsepower Net: 446@2400rpm
Gross: 500@2800rpm
Torque Net: 890 ft-lb@2200rpm
Gross: 955 ft-lb@2400rpm
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 detatchable 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. 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 installed on the rear of the tool rack. 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 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).


Home       Vehicle list       Top

                                                                                           



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. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.



Last updated 16 Jun 2013.

Questions? Comments? Corrections? Email me

© Copyright 2001-13 Chris Conners