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M3
M3A1

Scout Car M31-6

M3: General
Date of first acceptance 1935 Total acceptances 100
Manufacturer White Motor Co. Crew
8 men:
  • Observation commander in hull right front
  • Driver in hull left front
  • 6 passengers in hull rear
M3: Dimensions
Weight, net, equipped 8,135lbs
3,690kg
Height 81"
206cm
Length 202.50"
514.35cm
Width 80.37"
204.1cm
Front tread 63.75"
161.9cm
Rear tread 63.75"
161.9cm
Wheelbase 131"
333cm
Ground clearance 9.75"
24.8cm
Ground pressure, zero penetration 57psi
4.0kg/cm²
M3: Armament
Type Mount Traverse Elevation
.50cal M2HB MG Flexible on carriage mount M21 360°
(manual)
Manual
Two .30cal M1917A1 MG Flexible on carriage mounts M22 360°
(manual)
Manual
M3: Armor
Assembly
Bolting
Location Thickness
Windshield .50"
1.3cm
Other surfaces .25"
.64cm
M3: Automotive
Engine Hercules JXD; 6 cylinder, 4 cycle, in-line gasoline
Horsepower 95@3000rpm Torque 224 ft-lb@1100rpm Fuel capacity 26.5gal
100L
Transmission Clark Equipment Co. Model 230-F combination sliding and constant mesh, 4 speeds forward, 1 reverse
Steering Ross Gear and Tool Co. Type 660 cam and lever type, steering wheel
Brakes Hydraulic, internal expanding
M3: Suspension
Type Road wheels Shock absorbers
Semi-elliptic leaf spring 2/side On each wheel
M3: Performance
Max level road speed 55mph
89kph
Min turning diameter 29.25'
8.915m
Angle of approach 37° Angle of departure 35°
Max fording depth 22.50"
57.15cm

The scout car M2 had been based on the Corbitt 1.5-ton truck, was powered by Lycoming's "Corbitt Eight" MODGFC 94-horsepower V8 engine, weighed 7,900lb (3,600kg), and could travel at a maximum of 58mph (93kph). It had a cruising radius of 200 miles (320km), and a crew of 5-7 men. It was armored with .5" (1.3cm) plates on the front and .25" (.64cm) plates on the sides and rear. Four brackets for .30cal machine guns were mounted, two on each side. Twenty-two M2s, including prototypes, were produced from first quarter 1935-March 1938.

The 4x4 scout car M2A1, developed from the M2, was manufactured by the White Motor Company. It featured Tourelle skate mounts for its machine guns instead of the external pintle mounts found on the M2. The designation of M2A1 was changed to M3, and 100 M2A1/M3s were produced from 1937-9.

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Scout Car M3A11-10

M3A1: General
Date of first acceptance 1939 Total acceptances 20,894
Manufacturer White Motor Co. Crew
8 men:
  • Observation commander in hull right front
  • Driver in hull left front
  • 6 passengers in hull rear
M3A1: Dimensions
Combat weight 12,400lbs
5620kg
Height 78.5"
199cm
Length 221.5"
562.6cm
Width 80"
200cm
Front tread 63.25"
160.7cm
Rear tread 65.25"
165.7cm
Wheelbase 131"
333cm
Ground clearance 15.75"
40.01cm
Ground pressure, zero penetration 60psi
4.2kg/cm²
M3A1: Armament
Type Mount Ammunition Traverse Elevation
.50cal M2HB MG Flexible on cradle mount M30 750 rounds 360°
(manual)
Manual
.30cal M1919A4 MG Flexible on skate mount 8000 rounds 360°
(manual)
Manual
M3A1: Armor
Assembly
Bolting
Hull
Rolled face-hardened steel
Location Thickness Angle from vertical
Radiator louvres .25"
.64cm
30°
Windshield cover .50"
1.3cm
30°
Sides .25"
.64cm
Rear .25"
.64cm
Hood top .25"
.64cm
85°
M3A1: Automotive
Engine Hercules JXD; 6 cylinder, 4 cycle, in-line gasoline
Horsepower Net: 87@2400rpm Torque Net: 220 ft-lb@1150rpm Fuel capacity 30gal
110L
Transmission Combination sliding and constant mesh, 4 speeds forward, 1 reverse
Steering Steering wheel
Brakes Hydraulic, internal expanding
M3A1: Suspension
Type Road wheels Shock absorbers
Semi-elliptic leaf spring 2/side On each wheel
M3A1: Performance
Max level road speed 45mph
72kph
Max trench 18"
46cm
Max grade 60% Angle of approach 37°
Angle of departure 35° Max vertical obstacle 12"
30cm
Min turning diameter 57'
17m
Max fording depth 28"
71cm
Cruising range ~250mi, roads
~400km, roads

The M3A1 sported a wider body than the M3 with square corners and an overhung top, and its machine gun skate rail was lowered below the level of the armor. The rear door found on the M3 was deleted, and stowage and seating was changed. An anti-ditching roller was also added. A detachable canvas top was provided for the passenger compartment; it was supported by three bows and the windshield frame. The compression ratio in the JXD engine was raised to 5.88 from the M3's 5.78, yielding more power (110 gross horsepower at 3000rpm and 241 gross foot-pounds of torque at 1100rpm). The four-wheel drive system in these vehicles was full-time and could not be disengaged.

Beginning in mid-1940, 100 M3A1s were fitted with diesel engines for service testing with the Third Army. Two engines were used, either the Hercules DJXD or the Buda-Lanova Co.'s 6DT-317. The DJXD was a 6-cylinder, four-stroke engine that produced 103 brake horsepower at 2,600rpm and 233 foot-pounds of torque at 1,600rpm; the 6DT-317 was a 6-cylinder four-cycle solid-injection type that made 81 horsepower at 2,300rpm and 220 foot-pounds of torque at 1,200-1,600rpm. Starting the diesel engines required more torque and speed, so a second 12-volt battery was installed under the left-side door in a compartment similar to that for the original battery. The batteries were connected by a series-parallel switch so that when the starter button was pressed, they acted in series to power the 24-volt starter, and when the starter button was released they powered the normal 12-volt electrical system in parallel. When the testing was completed, the diesel cars were fed back into production so that usable parts could be recycled.

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References

  1. Hunnicutt, R.P. Armored Car: A History of American Wheeled Combat Vehicles. Novato, CA: Presidio Press, 2002. Reprinted from Armored Car, R.P. Hunnicutt ©2002, available from Presidio Press, 505B San Martin Drive, Suite 160, Novato, CA 94945.
  2. TM 9-705 Scout Cars, M3, M3A1, and 4.2 Mortar Motor Carriage, M2. Washington, DC: War Department, 19 February 1941.
  3. Doyle, David. U.S. Half-tracks: The Development and Deployment of the U.S. Army's Half-track Vehicles, Part one. Ed. Pat Stansell. Delray Beach, FL: The Ampersand Publishing Group, Inc., 2014.
  4. AGF Board No. 2. Development of Armored Vehicles, volume II: Armored Cars, Scout Cars, and Personnel Carriers.
  5. Crismon, Fred W. U.S. Military Wheeled Vehicles. Minneapolis: Victory Publishing, Ltd., 2001.
  6. Tank Data, vol. 3. Aberdeen Proving Ground, MD: US Army Ordnance School, Jul 1958.
  7. TM 9-705 Scout Car M3A1. Washington, DC: War Department, 26 October 1942.
  8. Catalogue of Standard Ordnance Items, 2nd edition 1944, volume 1. Washington, DC: Office of the Chief of Ordnance Technical Division, 1 June 1945.
  9. TM 9-2800 Standard Military Motor Vehicles. Washington, DC: War Dept., 1 Sep 1943.
  10. Hogg, Ian V. The Greenhill Armoured Fighting Vehicles Data Book. London: Greenhill Books, 2000.

Last updated 10 Oct 2021.
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