| Turreted M1: General | |||
| Date of first acceptance | 1935 | Total acceptances | 16 |
| Manufacturer | Rock Island Arsenal | Crew |
|
| Turreted M1: Dimensions | |||
| Combat weight | 27,000lbs 12,200kg |
Height | 85.2" on wheels 88" on tracks 216cm on wheels 224cm on tracks |
| Length | 193.2" 491cm |
Gun overhang forward | 0" |
| Width | 98.4" 250cm |
Tread | 85.2" 216cm |
| Ground clearance | 13.75" on wheels 16.25" on tracks 34.93cm on wheels 41.28cm on tracks |
Ground pressure | 10.6psi .744kg/cm² |
| Turreted M1: Armament | ||||
| Type | Mount | Ammunition | Traverse | Elevation |
| .50cal MG | Turret | 639 rounds | 360° (40° in mount, 20° left and right; manual) |
+40° to -15° (manual) |
| .30cal MG | Turret | 2,780 rounds | 360° (40° in mount, 20° left and right; manual) |
+40° to -15° (manual) |
| .30cal M2HB MG | Ball mount M8 in right bow | Manual | Manual | |
| Turreted M1: Armor | |
| Maximum | .625" 1.6cm |
| Minimum | .25" .64cm |
| Turreted M1: Automotive | |||
| Engine | Continental R-670; 7 cylinder, 4 cycle, radial gasoline | ||
| Horsepower | 268@2,400rpm | Fuel capacity | 41.5gal 157L |
| Transmission | Constant mesh | ||
| Steering | Controlled differential, steering levers when tracked; Gear and pinion, steering wheel when wheeled | ||
| Turreted M1: Suspension | ||
| Type | Road wheels | Track return rollers |
| Christie helical springs | 4 independently sprung dual/track | Flat track |
| Drive sprockets | Idlers | Shock absorbers | 14-tooth rear drive | At front of track | None |
| Turreted M1: Track | |||||||
| Center guide, single pin, rubber bushed steel | |||||||
| Width | 12" 30cm |
Pitch | 4.75" 12cm |
Shoes/track | 85 | Ground contact length | 106" 269cm |
| Turreted M1: Performance | |||
| Max level road speed | Wheeled: 37.8mph Tracked: 23.9mph Wheeled: 60.8kph Tracked: 38.5kph |
Max vertical obstacle | 15" 38cm |
| Max fording depth | Tracked: 35.75" Wheeled: 33.5" Tracked: 90.81cm Wheeled: 85.1cm |
Radius of action | Tracked: 55mi Wheeled: 118mi Tracked: 89km Wheeled: 190km |
The convertible medium tank M1 utilized J. Walter Christie's famous suspension design, and was able to run on either tracks or only its road wheels. When running on wheels, a chain was connected from the final drives to the rear road wheels and the tracks were stored on the vehicle's fenders. Standardization was proposed and rejected in February 1936, but was achieved when again proposed in March 1939. The tanks were declared obsolete the next March.
| Barbette M1: General | |||
| Date of first acceptance | 1935 | Total acceptances | 3 |
| Manufacturer | Rock Island Arsenal | Crew |
|
| Barbette M1: Dimensions | |||
| Combat weight | 30,000lbs 13,600kg |
Height | 79" 200cm |
| Length | 193" 490cm |
Gun overhang forward | 0" |
| Width | 98.4" 250cm |
Tread | 85.2" 216cm |
| Barbette M1: Armament | |
| Type | Mount |
| .50cal MG | Barbette front |
| .30cal MG | Barbette front, sides, rear |
| .30cal M2HB MG | Ball mount M8 in right bow |
| Barbette M1: Armor | |
| Maximum | .625" 1.6cm |
| Minimum | .25" .64cm |
| Barbette M1: Automotive | |||
| Engine | Continental R-670; 7 cylinder, 4 cycle, radial gasoline | ||
| Horsepower | 268@2,400rpm | Fuel capacity | 79.5gal 301L |
| Transmission | Constant mesh | ||
| Steering | Controlled differential, steering levers when tracked; Gear and pinion, steering wheel when wheeled | ||
| Barbette M1: Suspension | ||
| Type | Road wheels | Track return rollers |
| Christie helical springs | 4 independently sprung dual/track | Flat track |
| Drive sprockets | Idlers | Shock absorbers | 14-tooth rear drive | At front of track | None |
| Barbette M1: Track | |||||||
| Center guide, single pin, rubber bushed steel | |||||||
| Width | 12" 30cm |
Pitch | 4.75" 12cm |
Shoes/track | 85 | Ground contact length | 106" 269cm |
| Barbette M1: Performance | |
| Max level road speed | Wheeled: 44mph Tracked: 30mph Wheeled: 71kph Tracked: 48kph |
Three convertible medium tanks M1 were built without turrets, but rather with a square barbette superstructure. Besides the .50cal and .30cal machine guns in the forward plate, a .30cal MG was fitted in each side of the superstructure and also at the rear.
