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M50
M50A1

Multiple 106mm Self-propelled Rifle M501-2
M50: General
Date of first acceptance 1955 Total acceptances 297
Manufacturer Allis-Chalmers Manufacturing Co. Crew
3 men:
  • Gunner in hull center rear
  • Driver in hull left front
  • Loader in hull center rear
M50: Dimensions
Combat weight 19,050lbs
8641kg		 Height 83.9"
213cm
Length 150.8"
383.0cm		 Width over fenders 102.3"
259.8cm
Tread 73.0"
185cm		 Ground clearance 14.6"
37.1cm
Fire height, top rifles ~78"
~200cm		 Turret ring diameter 31.7"
80.5cm
Ground pressure, zero penetration 5.1psi
.36kg/cm²
M50: Armament
Type Mount Ammunition Traverse Elevation
Six 106mm Recoilless Rifles M40A1C T149E5 on turret 18 rounds 80°
(40° left and right;
manual)		 +20° to -10°
(manual)
.30cal M1919A4 MG Fixed or flexible in turret mount 1000 rounds 360°
(Manual)		 Manual
Rangefinder
Four .50cal Spotting Rifles M8C on top of 106mm rifles;
80 rounds .50cal
M50: Armor
Assembly
Welding
Hull
Rolled homogeneous steel
Location Thickness Angle from vertical
Upper front .5"
1.3cm		 71°
Lower front .5"
1.3cm		 45°
Upper sides .5"
1.3cm		 42°
Lower sides .5"
1.3cm		 0°
Upper rear .5"
1.3cm		 27°
Lower rear .5"
1.3cm		 0°
Top .5"
1.3cm		 90°
Floor .25"
.64cm		 90°
Turret
Rolled homogeneous steel
Location Thickness Angle from vertical
Front .5"
1.3cm		 30°
Sides .5"
1.3cm		 30°
Rear .5"
1.3cm		 30°
Top .5"
1.3cm		 90°
M50: Automotive
Engine General Motors Model 302; 6 cylinder, 4 cycle, in-line gasoline
Horsepower Net: 124@2400rpm
Gross: 145@3400rpm		 Torque Net: 252 ft-lb@1400rpm
Gross: 255 ft-lb@2000rpm		 Fuel capacity 47gal
180L
Transmission Allison X-drive XT-90-2, 3 ranges forward, 1 reverse
Steering Mechanical clutch-brake, steering levers
Brakes Multiple disc
M50: Suspension
Type Road wheels Track return rollers
Torsilastic 4 individually sprung dual/track 4 track skid bumpers/track
Drive sprockets Idlers Shock absorbers
15-tooth front drive Rear road wheels serve as adjustable trailing idlers On first, second, and third road wheels/track
M50: Track
T123
Center and outside guide band type
Width 20"
51cm		 Pitch 60" long sections;
4" crossbar pitch
150cm long sections;
10cm crossbar pitch		 Shoes/track 5 sections/track;
75 crossbars/track		 Ground contact length 94.2"
239cm
M50: Performance
Max level road speed 30mph
48kph		 Max trench 54"
140cm
Max grade 60% Max vertical obstacle 28"
71cm
Min turning diameter 18'
5.5m		 Max fording depth 24"
61cm
Cruising range ~115mi, roads
~185km, roads


The M50, known as the Ontos, mounted six recoilless rifles, 3 per side, on a small turret atop its pyramid-like hull. The rifles were actually 105mm in diameter, but were dubbed 106mm rifles to prevent confusion with earlier 105mm rifles. The .50cal spotting rifles were mounted on top of the upper 106mm weapons, and the .30cal MG mount was in the center on the turret roof. Crew access included a driver's hatch in the front of the vehicle and double doors in the rear for the gunner and loader. All of the 106mm rifles on the M50 could be dismounted from the vehicle, but the top outer rifles were specially designated for ground use. Besides the six 106mm rounds stored in the loaded rifles, there was an eight-round ammunition compartment in the vehicle's bottom rear, and four more rounds were stowed in the right rear of the gunner's compartment. The 106mm rifles could only be loaded from outside the vehicle.

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Multiple 106mm Self-propelled Rifle M50A11,3
M50A1: General
Date of first acceptance 1963
Manufacturer Allis-Chalmers Manufacturing Co. Crew
3 men:
  • Gunner in hull center rear
  • Driver in hull left front
  • Loader in hull center rear
M50A1: Dimensions
Height 83.9"
213cm		 Length 150.8"
383.0cm
Width over fenders 102.3"
259.8cm		 Tread 73.0"
185cm
Ground clearance 14.6"
37.1cm		 Fire height, top rifles ~78"
~200cm
Turret ring diameter 31.7"
80.5cm
M50A1: Armament
Type Mount Ammunition Traverse Elevation
Six 106mm Recoilless Rifles M40A1C T149E5 on turret 18 rounds 80°
(40° left and right;
manual)		 +20° to -10°
(manual)
.30cal M1919A4 MG Fixed or flexible in turret mount 1000 rounds 360°
(Manual)		 Manual
Rangefinder
Four .50cal Spotting Rifles M8C on top of 106mm rifles;
80 rounds .50cal
M50A1: Armor
Assembly
Welding
Hull
Rolled homogeneous steel
Location Thickness Angle from vertical
Upper front .5"
1.3cm		 71°
Lower front .5"
1.3cm		 45°
Upper sides .5"
1.3cm		 42°
Lower sides .5"
1.3cm		 0°
Upper rear .5"
1.3cm		 27°
Lower rear .5"
1.3cm		 0°
Top .5"
1.3cm		 90°
Floor .25"
.64cm		 90°
Turret
Rolled homogeneous steel
Location Thickness Angle from vertical
Front .5"
1.3cm		 30°
Sides .5"
1.3cm		 30°
Rear .5"
1.3cm		 30°
Top .5"
1.3cm		 90°
M50A1: Automotive
Engine Chrysler HT-361-318; 8 cylinder, 4 cycle, vee gasoline
Horsepower Gross: 180@3450rpm Torque Gross: 283 ft-lb@2400rpm Fuel capacity 47gal
180L
Transmission Allison X-drive XT-90-5, 3 ranges forward, 1 reverse
Steering Mechanical clutch-brake, steering levers
Brakes Multiple disc
M50A1: Suspension
Type Road wheels Track return rollers
Torsilastic 4 individually sprung dual/track 4 track skid bumpers/track
Drive sprockets Idlers Shock absorbers
15-tooth front drive Rear road wheels serve as adjustable trailing idlers On first, second, and third road wheels/track
M50A1: Track
T123
Center and outside guide band type
Width 20"
51cm		 Pitch 60" long sections;
4" crossbar pitch
150cm long sections;
10cm crossbar pitch		 Shoes/track 5 sections/track;
75 crossbars/track		 Ground contact length 94.2"
239cm
M50A1: Performance
Max level road speed 30mph
48kph		 Max trench 54"
140cm
Max grade 60% Max vertical obstacle 28"
71cm
Min turning diameter 18'
5.5m		 Max fording depth 24"
61cm
Cruising range ~100mi, roads
~160km, roads


The M50A1 got a new engine and transmission, and can be differentiated from M50 by the engine cooling louvres on the engine and transmission access doors as well as above the engine compartment to the right of the driver.

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

  3. Estes, Kenneth W. Marines Under Armor. Annapolis, MD: Naval Institute Press, 2000.



Last updated 2 Dec 2007.

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