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United States' M22 light tank, Locust


T9E1 Light Tank prototype:
United State's T9E1 Prototype Light Tank
US Ordnance Dept.
M22 Light Tank mounted under plane wing.
United States' M22 Light Tank, Locust, mounted under a plane's wing
US Ordnance Dept.

M22 Light Tank. Looking inside turret basket with turret removed.
United States' M22 Light Tank, Locust. Looking inside turret basket with turret removed.
US Ordnance Dept.
M22 Light Tank's top view of the hatches and combination gun mount.
United States' M22 Light Tank, Locust
US Ordnance Dept.
M22 Light Tank:
United States' M22 Light Tank, Locust
US Ordnance Dept.

M22's Tracks and Tools:
United States' M22 Light Tank's Tracks and Tools
US Ordnance Dept.


Based on the development of airborne forces by the Germans and Russians, the US Army decided in February 1941 that it should have airborne forces with armor support. General Motors, Christie, and Marmon-Herrington were asked to submit designs in May 1941. Marmon-Herrington Corp. was selected and worked with the U.S. Army Ordnance Department Tank Engineering Division.

It was built with a welded hull and cast turret. The engine was located on the right side in the rear of the hull. The power train was located in the front and consisted of a fixed-ratio transfer case, a 4-speed transmission, and controlled differential.

To save on weight there was no power traverse or a gyrostabilizer.


The turret could be moved and four brackets were mounted above the suspension on the hull to allow for the tank to be attached to a C-54 Skymaster cargo airplane.

The British could carry the M22 in their Hamilcar glider.

Crew Compartment

The driver's hatch could be fastened open for driving in non-combat areas. A detachable windshield with cover was also provided. Two hatches in the roof of the turret and and escape hatch in the hull provided exit points.

Main Armament

The gun was mounted in a Combination Gun Mount, M53.

The 37 mm gun can fire a 1.9 lb AP shell with a muzzle velocity of 2,600'/sec.


There were two bogie assemblies that contained two wheels each side that used volute springs with two support rollers. The idler trailed on the ground in the rear.


The armor on the M22 wasn't thick enough to protect against .50 caliber guns.


The first prototype, the T9, was delivered in late 1941 and designated the Light Tank T9 (Airborne).

In January 1942, two pilot models designated T9E1 were ordered. The shape of the turret was altered, the power traverse, gyrostabilizers and bow machine guns were not installed to save weight. These were tested by the 28th Airborne Tank Battalion. One of the prototypes was sent to England for testing.

Tests were conducted even after production was ordered in 1943 to 1944. These were conducted by the Ordnance Department at the Aberdeen and General Motors Proving Grounds. The Armored Board conducted their tests at Fort Knox.

The Army Air Corps conducted tests with a C-54. Brackets were added to the hull sides to allow for lifting hooks to be used to attach the tank to the aircraft. However, it was found the turret had to be removed first.


500 were ordered in April 1942 before service tests had begun. Eventually 1,900 were ordered but due to design changes and manufacturing problems only 830 were delivered.

Standardized as the M22 in early 1943.

The Ordnance Committee redesignated it Limited Standard in September 1944.

  • T9: 1
  • T9E1: 2
    • Production: November 1942
  • T9E2: 2
  • M22: >800, 830
    • Production: April 1942 - March 1945, April 1943 - February 1944, ? - February 1944
    • Manufacturer: Marmon-Herrington


  • T9: Prototype. Had 37 mm main gun.
  • T9E1: Prototype. Hull shape changed. Powered traverse for the turret and the gyrostabilizer for the main armament was removed to save weight. Hull machine guns were removed to save weight.
  • T9E2: Design. Was to carry an 81 mm breech loading mortar.
  • M22: Production model.
  • T18 Light Tractor: M22 with no turret. Could carry the five member crew of a 105mm airborne howitzer that it towed. Only one converted and project cancelled in late 1943.


Never used in combat by US forces. No suitable glider or aircraft to transport it.

British Use:

Some had a Littlejohn adaptor installed which increased the barrel length.

British used them in the Normandy landings.
British forces did not use them in Normandy despite advertising by Marmon-Herington.

The British named it Locust and used it in the 6th Airborne Division in the Rhine crossing on March 22, 1945 / March 24, 1945. Were carried in the Hamilcar glider. Used with the Tetrarch during the crossing on March 24, 1945.


In July 1945, the M22 was declared obsolete as it was no longer going to be used.

Some of the surviving M22s were sold to Belgian scrap dealers and some of those may have ended up in Egypt.
Some were supplied to Egypt after the war.


Physical Characteristics  
Weight - empty  
Width over tracks  
Ground clearance  
Ground contact length  
Ground pressure  
Turret ring diameter  
Main 37 mm
MG - coaxial 1: .30 cal MG
MG - hull 2: .30 cal MG
Side arms  
Side arms  
Armor Thickness 1"
Hull Front, Upper  
Hull Front, Lower  
Hull Sides, Upper  
Hull Sides, Lower  
Hull Rear  
Hull Top  
Hull Bottom  
Turret Front  
Turret Sides  
Turret Rear  
Turret Top  
Engine (Make / Model)  
Bore / stroke  
Net HP  
Power to weight ratio  
Compression ratio  
Transmission (Type)  
Gear ratios - 1st speed  
- 2nd speed  
- 3rd speed  
- 4th speed  
- reverse  
Steering ratio  
Electrical system  
Fuel (Type)  
Road consumption  
Cross country consumption  
Speed - Road  
Speed - Cross Country  
Range - Road  
Range - Cross Country  
Turning radius  
Elevation limits  
Fording depth  
Trench crossing  
Vertical obstacle  
Climbing ability  
Suspension (Type) Two bogies with volute springs
Wheel size  
Wheels each side 4
Return rollers each side 2
Tracks (Type) T78 Carden-Loyd iron
Width 11.25"
Number of links  
Pitch 3"
Tire tread  
Track centers/tread  
  M22 light tank
Crew Commander, gunner, driver.
Radio SCR-510
Physical Characteristics  
Weight 16,000 lb, 16,400 lb, 16,452 lb, 17,024 lb
7.3 tons, 7.4 tons, 8.5 tons
7,417 kg, 7,439 kg , 7,445 kg
Weight - empty 14,490 lb
Length 12.9', 12' 11"
3.937 m, 3.94 m
Height 4' 1", 5' 4", 5' 8", 5' 8.5", 6' 1", 6.1'
1.73 m, 1.74 m, 1.854 m
Width 7' 1", 7' 3.75", 7' 4", 7' 4.5", 7.5'
2.159 m, 2.23 m, 2.24 m
Width over tracks  
Ground clearance 9.5", 10"
Ground contact length 8' 8", 109"
Ground pressure 6.7 psi, 7.03 psi, 7.2 psi
Turret ring diameter 47.5"
Main 1: 37 mm M6
1: 37 mm
1: 37 mm M6 L/37
1: 37 mm M6, L/53
MG 1: MG
1: 7.62 mm (.30 cal) MG
1: .30 cal Browning MG
1: .30" Browning MG
1: .30 cal MG
MG - coaxial 1: .30 cal Browning M1919A4 MG
1: .30 cal Browning MG
1: 7.62 mm / 0.3" MG
Side arms Tripod M2 .30 cal MG
3: .45 cal M3 submachine guns
Main 50
APC M51B1 or M51B2, AP M74, HE M63, Canister M2
MG 2,500
Side arms .45 cal: 450
Grenades: 12 (4: Fragmentation Mk II, 4: Smoke M8, 2: Thermite, 2: Offensive Mk III)
Armor Thickness 25
0.75" - 1"
Front: 0.98", 1"
Side: 0.4"
Hull Front, Upper 1"
Hull Front, Lower 1"
Hull Sides, Upper 0.375@45°, 0.75"
Hull Sides, Lower 0.5"
Hull Rear 0.5"
Hull Top 3/8"
Hull Bottom 0.5"
Turret Front 0.6", 1"
Mantlet: 0.6"
Turret Sides 1"
Turret Rear 0.75"
Turret Top 0.375 - 0.75", 0.75"
Engine (Make / Model) Lycoming 0-435T, Lycoming, Lycoming O-435-T
Bore / stroke  
Cooling Air
Cylinders Radial 6, 6, 6 horizontally opposed
Net HP 162, 162@2,800 rpm
Power to weight ratio  
Compression ratio  
Transmission (Type) Marmon-Herrington Synchromesh
4 forward, 1 reverse
Gear ratios - 1st speed 1.857:1
- 2nd speed 1:1
- 3rd speed 0.463:1
- 4th speed 0.304:1
- reverse 1.666:1
Steering Controlled differntial
Steering ratio  
Starter Electric
Electrical system 12 volt
Fuel (Type)  
Octane 80
Quantity 55 gallons, 57 gallons
Road consumption 2.5 mpg
Cross country consumption  
Traverse 360°, hand
Speed - Road 35 mph, 40 mph
64 kph
Speed - Cross Country 27 mph, 30 mph, 35 mph
48 kph
Range - Road 110 miles, 135 miles
217 km
Range - Cross Country  
Turning radius 20', 40'
Elevation limits -10° to +30°
Fording depth 3', 3' 2", 3' 6"
Trench crossing 5' 5"
Vertical obstacle 1' - 1' 6", 12.4", 1' 0.5", 1' 4"
Climbing ability 27°, 32° (63%) slope, 50%
Suspension (Type) Two bogie assemblies that contained two wheels each side that used volute springs with two support rollers
Vertical volute springs
Wheel size 15" x 6"
Wheels each side 4
Return rollers each side 2
Tracks (Type) Dry pin, Steel T78
Width 11.25", 11.5"
0.286 m
Number of links 106
Pitch 3", 3.1"
Tire tread  
Track centers/tread 5.4', 5.9', 5' 10.5"
1.791 m


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  3. Tanks of the World, 1915-1945, Peter Chamberlain, Chris Ellis, 1972
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  8. The American Arsenal, 1996
  9. World War I and II Tanks, George Forty, 2012
20th Century American Military History Crucial Site