M5 Light Tank:

Patton Museum in Ft Knox, Kentucky
United States M5 Light Tank
Chris Bobo

Image: M5 (17K)

In the fall of 1941 Cadillac suggested to the Ordnance Department that they should try the M3 with a twin Cadillac engine due to radial engine shortages that were used by the aircraft industry1. It was also to have the Cadillac Hydra-matic transmission that was used in automobiles.

The Ordnance Board was convinced that a car engine would work, so Cadillac converted a tank and drove it for 500 miles at a testing ground.1 The test showed it to have a smooth ride and was easy to operate. The Ordnance Board was convinced and production commenced.1

Due to the shortage of the Continental engines this was standardized for production in February 1942. It was originally going to be designated the M4 Light Tank, but it was decided to use M5 to avoid confusion with the M4 Medium.

In July 1943, another Cadillac production facility in Southgate, California, and Massey-Harris in Racine, Wisconsin, also started production. When M3 production ceased in October 1943, American Car & Foundry started production of the M5.

Standardized in February 1942.1 Production started in July 1942.
First production units were delivered at the end of March 1942.7

In February 1942 an M3A1 had 2 Cadillac liquid cooled V-8 car engines installed which meant that the rear deck had to be raised. Fuel tanks were put in the rear corners of the hull. Radiators were placed above the engines.

The flywheel in each engine was connected to the Hydra-Matic Transmission. Since the drive shaft from the Cadillac engines and the Hydra-Matic transmission, some of the traversing mechanisms and parts of the gun stabilizer were moved under the turret basket and this provided more room for the commander and gunner. The turret was extended in back to accommodate the radio.

A single cylinder engine supplied auxiliary power and charged the batteries.

The seats for the driver and assistant driver could be locked in any position. The seats went up under spring pressure and down under body weight. The driver and assistant driver had 360° periscopes in the roof of the hull.

Four escape hatches were provided.

It was used as a training vehicle, and used as a scouting and reconnaissance vehicle in combat.

M5A1:

USA's M5A1 Light Tank Drawing
Aberdeen Tank Museum


Aberdeen Tank Museum

Standardized in September 1942. Classified as Substitute Standard in July 1944. First productions models were completed in December 1942.7

All welded. Had improved turret with more room and radio bulge in rear, with the antenna above the bulge. There was a plate in the bulge that allowed the 37 mm gun to be removed for maintenance. Another periscope in turret for viewing rear better. The commander had a direction finder fastened to the turret roof to indicate the straight ahead position. There was also a spotlight provided.

The antiaircraft gun mounting was moved to the right side of the turret. The commander could traverse the turret and fire the antiaircraft gun at the same time.

Larger escape hatches and positive water sealing door latches installed. An additional escape hatch in the floor of the hull is installed. Pistol ports are supplied with locks.

Had the Combination Gun Mount, M44, installed in the turret. This had a direct 3-power telescope.

The 37 mm gun fired a 1.9 lb shell at a muzzle velocity of 2,600'/sec.9

M5 Command Tank:

Turret removed and replaced by box structure.

M5A1 with Psy-war equipment:

Fitted with PA system. 1944-45.

M5A1 with E7-7 Flame Gun:

Main gun replaced by flame thrower equipment.

M5A1 with E9-9 Flame-throwing equipment:

Based on British Crocodile. Prototype only.

M5A1 with E8 Flame-gun:

Original turret removed. Box like superstructure was added with a smaller turret with flame thrower coming from it. Prototype only.

M5 with T39 Rocket Launcher:

T39 launcher mounted on turret top. Fired 20 7.2" rockets. Project only.

M5 Dozer:

Turret removed and dozer blade added. 1944. Few had turret remain.

T8 Reconnaissance Vehicle:

Removed turret and added mounting for .50 cal MG. 1944-45.

T27, T27E1 81 mm Mortar Motor Carriage:

The army wanted a mortar carrier based on the M5A1 chassis. The T27 prototype had the turret removed and an armored superstructure installed. The mortar was to fire forward with a 35 degree traverse. A .50 cal MG was also installed. The T27E1 had the mortar lower in the hull so that it didn't stick above the superstructure. Project canceled in April 1944 due to inadequate crew and storage space.

T29 4.2" Mortar Motor Carriage:

After the T27 was canceled a design that had more space internally and used a smaller mortar was devised, however, this too had too small of space.

M5 or M5A1 with Cullin Hedgerow Device:

Prongs added to front of vehicle. Normandy, 1944.

British Service:
Nicknamed "Honey" by British calvary regiments. 84 sent to 8th Army in July 1941.1 Used in Burma7, New Guinea7, Iraq7, Britain, NW Europe7, Italy7, and North Africa7. Russia1, China1, New Zealand1, and France received some as well.

The British were reported to like this tank at the time of its introduction. It could go about 10-20 mph faster than their own or enemy tanks, and required less maintenance.

United Kingdom Use

Stuart VI:

M5 and M5A1.

Stuart Kangaroo:

Removed turret and added seats.

Stuart Recce:

As Kangaroo but with various MGs on pindle mounts.

Stuart Command:

As Kangaroo but with extra radios.

Stuart 18 pdr. SP:

At least one Stuart had it's turret replaced by an 18 pdr field gun.

  M5 (Stuart VI) M5A1
Crew Commander, gunner, driver, co-driver.3
41,3,4
Commander, gunner, driver, co-driver.3
43,4,9
Physical Characteristics    
Weight 33,000 lb3
14.7 tons1,7, 15 tons4,6
14,969 kg1
33,907 lb3,4, 34,700 lb
16.9 tons9
Length w/gun 14' 2.75"3,4, 14' 3"1,7
4.34 m1,6
15.9'9, 15' 10.5"3,4
Length w/o gun    
Height 7' 6"7, 7' 6.5"3,4, 7' 7"1
2.29 m6, 2.3 m1
7.5'9, 7' 6.5"3, 7' 10.5"4
Width 7' 4"7, 7' 4.25"3,4, 7' 5"1
2.24 m6, 2.25 m1
7" 4.25"3, 7' 5", 7' 6"4,9
Width over tracks    
Ground clearance 13.75" 13.75", 15"9
Ground contact length 117" 117", 120"9
Ground pressure 12.4 psi 11.4 psi9, 12.5 psi
Turret ring diameter 46.75" 46.75"
Armament    
Main 37 mm M61,3
37 mm4
37 mm M63
37 mm4,9
Secondary    
MG 2: MG4
3: 7.62 (.30 cal) MG1
2: .30 cal Browning, coaxial, hull, AA
2: .30 cal Browning MGs, most had additional MG as AA.3
3: MG4
2: .30 cal Browning, coaxial, hull, AA
2: .30 cal Browning MGs, most had additional MG as AA.3
2: .30 cal M1919A4 MGs9
2: .30 cal M1919A5 MGs9
Side arms .30 cal M2 tripod mount
.45 cal submachine gun
Grenades
.30 cal M2 tripod mount
.45 cal submachine gun
Grenades
Quantity    
Main 1231, 1333 1473,9
Secondary    
MG 6,2503 6,5003,9
Side arms .45: 420 .45: 540
Grenades: 12
Armor Thickness (mm) 123, 673
12 - 674
Front: 506
Side: 286
123 , 673
12 - 674
Front: 1.5"9
Side: 1.1"9
Hull Front, Upper 1 1/8" (2.5") 1 1/8" (2.5")
Hull Front, Lower 2-2.5"@90° 2-2.5"@90°
Hull Sides, Upper 1-1 1/8"@0° 1-1 1/8"@0°
Hull Sides, Lower    
Hull Rear 1-1 1/8"@0° 1-1 1/8"@0°
Hull Top 0.5"@90° 0.5"@90°
Hull Bottom 3/8-0.5"@90° 3/8-0.5"@90°
Turret Front 1.75" (2") 1.75" (2")
0.5"9
Mantlet: 2"9
Turret Sides 1.25"@0° 1.25"@0°
1.25"9
Turret Rear 1.25"@0° 1.25"@0°
Turret Top 0.5"@90° 0.5"@90°
Engine (Make / Model) Cadillac Twin1,3,4,7 Cadillac Twin1,3,4
2xCadillac9
Bore / stroke    
Cooling   Water9
Cylinders V-87 2xV-89
Capacity    
Net HP 1214, 2206 1214, 260@3,600 rpm9
Power to weight ratio 15 hp / ton7  
Compression ratio   7.1:19
Transmission (Type) Hydra-Matic
6 forward, 1 reverse
Hydramatic9
4 forward, 1 reverse, 2 speed transfer case9
6 forward, 1 reverse
Steering   Controlled differential9
Steering ratio    
Starter   Electric9
Electrical system   12-volt9
Ignition   Distributors9
Fuel (Type)   Gasoline9
Octane    
Quantity 89 gallons 82 gallons9, 89 gallons
Road consumption   1.2 mpg9
Cross country consumption    
Performance    
Traverse 360°3, hydraulic or hand 360°3, hydraulic or hand9
Max speed 36 mph3,7, 37 mph1, 40 mph4
58 kph1, 60 kph6
36 mph3,9, 40 mph4
Cross country 24 mph3 20-25 mph9, 24 mph3
Road radius 100 miles1,3,7
161 km1
100 miles3, 160 miles9
Cross country radius   100 miles9
Turning radius 21' 21'
Elevation limits -10° to +20°3 -10° to +20°3
Fording depth 3'3 3'3,9
Trench crossing 5' 4"3 5.3'9, 5' 4"3
Vertical obstacle 1' 6"3 1' 6"3,9
Climbing ability   31° (60%) slope9
Suspension (Type) Vertical volute.3 Vertical volute3
Vertical volute spring9
Wheels each side 4 49
Return rollers each side 3 39
Tracks (Type)   Rubber bushed, double pin9
Length    
Width 11 5/8"3 11 5/8"3, 11.6"9
Number of links   1329
Pitch   5.5"9
Tires    
Track centers/tread 6' 1.5"3 6.1'9, 6' 1.5"3
Production 3/1942- : 2,0747
Cadillac and Massey Harris, 5/1942-12/1942: 2,074, 2,0751
12/1942 - 6/1944: 6,8107
Cadillac, Massey Harris, American Car & Foundry, 11/1942-6/1944: 6,8101
American Car & Foundary Co., Cadillac Motor Division (GMC), Massey Harris Co.9
1942: ACF10

Sources:

  1. The Encyclopedia of Tanks and Armored Fighting Vehicles - The Comprehensive Guide to Over 900 Armored Fighting Vehicles From 1915 to the Present Day, General Editor: Christopher F. Foss, 2002
  2. Panzer Truppen The Complete Guide to the Creation and Combat Employment of Germany's Tank Force 1933-1942, Thomas L. Jentz, 1996
  3. British and American Tanks of World War Two, The Complete Illustrated History of British, American, and Commonwealth Tanks 1933-1945, Peter Chamberlain and Chris Ellis, 1969
  4. Tanks of the World, 1915-1945, Peter Chamberlain, Chris Ellis, 1972
  5. The Encyclopedia of Weapons of World War II, Chris Bishop, 1998
  6. Jane's World War II Tanks and Fighting Vehicles The Complete Guide, Leland Ness, 2002
  7. Tanks of World War II, Duncan Crow, 1979
  8. Battle Winning Tanks, Aircraft & Warships of World War II, David Miller, 2000
  9. Tank Data, Aberdeen Proving Grounds Series, 1968?
  10. Tank Data 2, Aberdeen Proving Grounds Series, E. J. Hoffschmidt and W. H. Tantum IV, 1969
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