57mm Gun Motor Carriage T481-12

T48: General
Date of first acceptance December 1942 Total acceptances 962
(281 converted to M3A1 personnel carriers)
Manufacturer Diamond T Motor Car Co. Crew
5 men:
  • Gun commander in rear
  • Gunner in rear
  • Driver in cab left
  • Assistant driver in cab right
  • Loader in rear
T48: Dimensions
Combat weight 19,000lbs
Height over gun shield 90"
Length with roller 252.63"
Gun overhang forward 0"
Width over side armor 77.25"
Fire height 72"
Front tread 64.5"
Rear tread 63.8"
Wheelbase 135.5"
Ground clearance 11.2"
Ground pressure, tires 33psi
T48: Armament
Type Mount Ammunition Traverse Elevation
57mm Gun M1 Mount T5 99 rounds
(20 ready)
(27.5° left and right;
+15° to -5°
Aiming equipment
Telescope M18 for gunner
T48: Armor
Rolled face-hardened steel
Location Thickness Angle from vertical
Gun shield front .625"
Gun shield sides .25"
Gun shield top .25"
Radiator louvres .25"
Windshield cover .50"
Sides .25"
Rear .25"
Hood top .25"
T48: Automotive
Engine White 160AX; 6 cylinder, 4 cycle, in-line gasoline
Horsepower Net: 147@3,000rpm Torque Net: 325 ft-lb@1,200rpm Fuel capacity 60gal
Transmission Spicer 3461 constant mesh, 4 speeds forward, 1 reverse
Steering Steering wheel
Brakes Hydraulic (Hydrovac)
T48: Suspension
Type Road wheels Track return rollers
Front: Semi-elliptic longitudinal leaf spring
Rear: Vertical volute spring
Front: Steel ventilated disc
Rear: 1 bogie/track;
4 dual/bogie
1 dual/track
Drive sprockets Idlers Shock absorbers
18-tooth front drive Adjustable fixed at rear of track On front wheels
T48: Track
Center guide band type
Width 12"
Pitch 4"
Pitches/track 58 Track ground contact length 46.75"
T48: Performance
Max level road speed 45mph
Max grade 60%
Angle of approach 33° Angle of departure 45°
Max vertical obstacle 12"
Min turning diameter 59'
Max fording depth 32"
Cruising range ~200mi, roads
~320km, roads

The T48 was mainly intended for shipment to allies under Lend-Lease, and the 57mm gun M1 was an American version of the British long-barreled 6 pounder Mark V. The T48 was set up much like the M3 75mm GMC, with the gun in the passenger compartment firing forward and a notch in the downward-folding armored windshield cover. The roof of the driving compartment was removed, and a travel lock was attached to the hood. The T5 gun mount placed the top of the 57mm gun carriage M1 on top of a conical mount. The T48 was fitted with the small, demountable headlights after the 75mm GMC M3's large fender-mounted lights were damaged by muzzle blasts. The T48's hood was also reinforced to prevent damage from the firing of the gun. An ammunition rack was situated at the rear of the passenger compartment. Twenty ready rounds could be stowed in the top portion of the rack behind a hinged cover, and forty rounds in their fiberboard tubes could be stowed below the ready rack.




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  2. Doyle, David. U.S. Half-tracks: The Development and Deployment of the U.S. Army's Half-track Based Multiple Gun Motor Carriages and Gun Motor Carriages, Part two. Ed. Pat Stansell. Delray Beach, FL: The Ampersand Publishing Group, Inc., 2016.
  3. FM 23-75 57-mm Gun M1. Washington, DC: War Department, 15 June 1944.
  4. TM 9-2800 Standard Military Motor Vehicles. Washington, DC: War Department, 1 September 1943.
  5. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.
  6. Chamberlain, Peter, and Chris Ellis. British and American Tanks of World War Two. Frome, England: Cassell & Co., 2000.
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  9. SNL G-102 Service Parts Catalog for Cars, Half-track, M2 and M2A1; Carriers, Personnel, Half-track, M3 and M3A1; Carriages, Motor, 75-mm Gun, M3 and M3A1; Carriers, 81-mm Mortar, Half-track, M4 and M4A1; Carrier, 81-mm Mortar, Half-track, M21; Carriage, Motor, Multiple Gun, M13; Carriages, Motor, Multiple Gun, M15 and M15A1; Carriage, Motor, Multiple Gun, M16; Carriage, Motor, 105-mm Howitzer, T19; Carriage, Motor, 75-mm Howitzer, T30; Carriage, Motor, 57-mm Gun, T48. 30 September 1943.
  10. Tank Data, vol. 2. Aberdeen Proving Ground, MD: US Army Ordnance School, July 1958.
  11. Siemers, Cary. "USA's Half Track Gun Motor/Mortar Carriages." World War II Tanks & Vehicles and Advanced Squad Leader. 4 July 2001. 13 August 2001 <http://www.siemers.com/wwii/USA/GunMotorCarriage.htm>.
  12. Track Data. Warren, MI: Track & Suspension Laboratory, Components Research and Development Laboratories, Research & Engineering Directorate, US Army Tank-Automotive Center, 23 June 1965.
Last updated 6 Jan 2024.
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© Copyright 2001-24 Chris Conners