| M2: General | |||
| Date of first acceptance | 1939 | Total acceptances | 18 |
| Manufacturer | Rock Island Arsenal | Crew | 5 men |
| M2: Dimensions | |||
| Combat weight | 38,020lbs 17,250kg |
Height | 112" 284cm |
| Length | 212" 538cm |
Gun overhang forward | 0" |
| Width | 103" 262cm |
Tread | 81" 206cm |
| Ground pressure, zero penetration | 18.8psi 1.32kg/cm² |
||
| M2: Armament | ||
| Type | Mount | Traverse |
| 37mm Gun M3 | Turret | 360° (manual) |
| Two .30cal MGs | Sponson AA mounts | Manual |
| Four .30cal MGs | Rotors in sponsons | ~90° (manual) |
| Two .30cal MGs | Fixed in either bow | None |
| M2: Armor | |
| Assembly | |
| Riveting | |
| Hull | |
| Face-hardened armor | |
| Location | Thickness |
| Lower front | 1.125" 2.858cm |
| Floor | .25" .64cm |
| Top | .375" .953cm |
| M2: Automotive | |||
| Engine | Wright R975; 9 cylinder, radial gasoline | ||
| Horsepower | 350 | Fuel capacity | 125gal 473L |
| Transmission | Constant mesh, 5 speeds forward, 1 reverse | ||
| Steering | Controlled differential, steering levers | ||
| Brakes | Mechanical, external contracting | ||
| M2: Suspension | ||
| Type | Road wheels | Track return rollers |
| Vertical volute spring | 3 bogies/track; 2 wheels/bogie |
1 at top of each bogie |
| Drive sprockets | Idlers | Shock absorbers | 13-tooth front drive | Adjustable at rear of track | None |
| M2: Track | |
| Outside guide, double pin, smooth rubber | |
| Width | 13.25" 33.66cm |
| M2: Performance | |
| Max level road speed | 26mph 42kph |
The medium tank M2 was basically a bigger version of the light tank M2, and used many components of the light tank; indeed the design of the medium's vertical volute spring suspension was based on that of the light tank M2's. The medium tank M2 had a turret with sloping sides and cooling fins on the final drive and differential housings. The sponson machine guns were mounted at the corners of the fighting compartment, and the anti-aircraft machine guns were mounted on top of either sponson.
| M2A1: General | |||
| Date of first acceptance | December 1940 | Total acceptances | 94 |
| Manufacturers |
|
Crew | 5 men |
| M2A1: Dimensions | |||
| Combat weight | 41,315lbs 18,740kg |
Height | 108" 274cm |
| Length | 212" 538cm |
Gun overhang forward | 0" |
| Width | 103" 262cm |
Tread | 81" 206cm |
| Ground pressure, zero penetration | 15.3psi 1.07kg/cm² |
||
| M2A1: Armament | ||||
| Type | Mount | Traverse | Elevation | |
| 37mm Gun M5 | M19 or M21 in turret | 360°; 20° in mount (manual) |
+20° to -10° (manual) | |
| Two .30cal MGs | Sponson AA mounts | Manual | Manual | |
| Four .30cal MGs | Sponson mounts | ~90° (manual) |
Manual | |
| Two .30cal MGs | Fixed in either bow | None | None | |
| Aiming equipment | ||||
| Telescope M5A1 for gunner; telescopes for sponson machine guns | ||||
| M2A1: Armor | |
| Assembly | |
| Riveting | |
| Hull | |
| Face-hardened armor | |
| Location | Thickness |
| Lower front | 1.125" 2.858cm |
| Floor | .25" .64cm |
| Top | .375" .953cm |
| All vertical surfaces | 1.25" 3.18cm |
| M2A1: Automotive | |||||
| Engine | Wright R975 EC2; 9 cylinder, 4 cycle, radial gasoline | ||||
| Horsepower | Net: 340@2,400rpm Gross: 400@2,400rpm |
Torque | Net: 800 ft-lb@1,800rpm Gross: 890 ft-lb@1,800rpm |
Fuel capacity | 125gal 473L |
| Transmission | Constant mesh, 5 speeds forward, 1 reverse | ||||
| Steering | Controlled differential, steering levers | ||||
| Brakes | Mechanical, external contracting | ||||
| M2A1: Suspension | ||
| Type | Road wheels | Track return rollers |
| Vertical volute spring | 3 bogies/track; 2 wheels/bogie |
1 at top of each bogie |
| Drive sprockets | Idlers | Shock absorbers | 13-tooth front drive | Adjustable at rear of track | None |
| M2A1: Track | |
| Outside guide, double pin, smooth rubber | |
| Width | 14.25" 36.20cm |
| M2A1: Performance | |
| Max level road speed | 26mph 42kph |
M2A1 featured a new vertical-walled turret, and the turret door was moved from the turret rear to the top of the turret. The gun mount M19 added armor to the gun barrel and recoil mechanism, while the later M21 featured a shorter recoil tube that was brought into the tank for protection, eliminating the recoil tube guard and some of the gun's muzzle preponderance. Bullet splash deflectors were added to the sloping hull front. The M2A1's sponson machine guns were fitted with tubular sights and rotor shields. The 37mm gun M5 was modified from the 37mm gun M3 by making the gun tube 5.1" (13cm), or 3.5 calibers, shorter to try to reduce the chance of damage from fouling the gun on obstacles or trees. The pistol ports were also changed from a design with internal shutters to one with outward-opening flaps.
