T48 Gun Motor Carriage

The T48 57 mm Gun Motor Carriage was a self-propelled anti-tank gun produced by the Diamond T company in 1943 for the United States. The design was a 57 mm gun M1 (US production of a British design) mounted on a M3 Half-track.

A total of 962 vehicles were produced from 1943 to 1945. It had originally been planned that Britain would receive all of the examples produced through Lend-Lease, intending to use them in the Western Desert, but by the time they arrived the campaign was over. As a result, the British transferred 650 half-tracks to the Soviet Union under the Soviet Aid Programme. Britain retained 31 and the remainder were taken by the US Army; these British and American vehicles were converted back to standard M3 half-tracks.

The Soviets called it the SU-57 (Samokhodnaya ustanovka 57), and under this designation it served in Operation Bagration and other fighting on the Eastern Front during World War II.

Specifications

The T48 Gun Motor Carriage was 21 ft long (6.40 m), 7 ft 1 in (2.16 m) wide, 7 ft (2.13 m) high with a wheelbase of 135.5 in (3.44 m), and weighing 9.45 tonnes (20,800 lb).^[1] The suspension consisted of a leaf spring for the wheels and the front tread had Vertical Volute springs. The vehicle had a maximum speed of 45 mph (72 km/h). With a fuel capacity of 60 US gallons (230 l), it had a range of 150 miles (240 km), and was powered by a 128 hp (95 kW)^[2] White 160AX, 386 in³ (6,330 cc),^[3] 6 cylinder, petrol engine with a compression ratio of 6:3:1. The power to weight ratio was 15.8 hp/tonne. It also had 6–12 mm of armor, was armed with a single 57 mm Gun M1,^[1] and had a crew of five.^[4]

Development

T48 in the Muzeum Wojska Polskiego

The T48 originated from an Anglo-American requirement for a self-propelled 6-pounder anti-tank gun.^{[5][lower-alpha 1]} The American requirement was dropped later. It was made by emplacing a 57 mm gun M1 – the US production version of the British Ordnance QF 6-pounder – in the rear of a M3 Half-track. The first production batch was ordered in April 1942. It was intended solely for Lend-Lease; the T48 was never officially type-classified.^[7]

Pilot model

The pilot model was built at the Aberdeen Proving Ground in May 1942. The 57 mm Gun M1 was mounted in the M12 recoil mechanism and installed on a tubular pedestal. The tublar pedestal was soon replaced with a conical structure that was designated the "57 mm gun mount T5". The gun on the pilot model had a traverse of 27.5 degrees either side of the centreline (total of 55 degrees), while having an elevation of +15 to -5 degrees. The short-barrelled (43 caliber) British Mark III 6 pounder gun was installed in the pilot, but the longer-barrelled (50 caliber) 57 mm Gun M1 was specified for the production models. The original travel lock – to hold the gun in a fixed position when the vehicle was moving – proved to be unsatisfactory, and was replaced by a travel lock on the front hood. The original design had a gun shield taken from the T44 57 mm Gun Motor Carriage. After the first tests were complete, a new shield was designed with 5/8 inch thick face-hardened steel on the front and 1/4 inch thick on the sides and top. The shield extended over the crew with a relatively low silhouette of only 90 in (2.3 m). Learning from experience with the M3 Gun Motor Carriage in the Phillipines Campaign, demountable headlights were used.^{[8][lower-alpha 2][6]} The T48 was accepted for production in 1942.^[7]

Service history

A T48 in the Kubinka tank museum.

Deliveries of the T48 were made in 1942 and 1943, with 50 being delivered in 1942 and 912 being delivered in 1943. The British ordered all of the T48s that were produced, intending to use them in the Western Desert Campaign, but by the time they arrived (in summer 1943), the British had already won the war in the Western Desert and the appearance of the 75 mm gun from the U.S., and later the Ordnance QF 17-pounder gun, which meant that the T48 was surplus to British requirements. As a result, the vehicles were almost immediately shipped to the Soviet Union under the terms of the Soviet Aid Programme. Through this programme, the Soviets accepted 650 vehicles,^[3][10] adopting the designation SU-57. A small number were later passed to the Polish People's Army.^[7][11][12]

Britain accepted 30,^[4] converting them back to carriers. The US retained 281 vehicles which were also converted back to M3A1 standard carriers^[10][13] in 1944.^[10] They were converted by the Chester Tank Depot.^[9] The U.S. Army also accepted one.^[4] The Wehrmacht captured and operated several T48s from Britain (as carriers) and the Soviet Union.^[7]

The T48 served with the 16th Separate Tank Destroyer Brigade in 1943 during the offensive across the Dnieper River, and with the 19th Brigade during the Baranow bridgehead battle in August 1944. The T48 also served with the Soviet 22nd Self-Propelled Artillery Brigade. Some of these units mentioned above took part in the Berlin and Prague offensives. The Polish People's Army used its T48s in the 7th Self-Propelled Artillery Battery in the Soviet attacks into Germany and Poland.^[14][15]

One strategy the Soviets used was putting brigades equipped with the right behind the infantry,^{[lower-alpha 3]} which then the brigade commander would spread out the T48s due to the long range of the 57 mm gun. The best tactic was putting them in a hull-down position behind a ridge or hill.^[16]

Operators

• Wehrmacht units operated a small number of T48s captured from UK and the Soviet Union.^[7]
• Polish Army in the East received 15 vehicles operated previously by the Red Army.^[9]
• Red Army operated T48 GMC under the designation SU-57.^[7][17]
• British Army accepted 31 vehicles, later rebuilt as carriers.^[7][10]
• US Army used T48s rebuilt as M3A1 half-tracks, in 1944.^[10] Rebuilt by the Chester Tank Depot.^[9][13]

See also

• Deacon (artillery) – British 6-pdr gun on armoured truck
• List of U.S. military vehicles by supply catalog designation

References

Notes

Citations

Bibliography

• Berndt, Thomas (1993). Standard Catalog of U.S. Military Vehicles. Iola, WI: Krause Publications. ISBN 0-87341-223-0
• Berndt, Thomas (1994). American Tanks of World War II. Minnesota, MN: MBI Publishing Company. ISBN 0-87938-930-3
• Chamberlain, Peter; Ellis, Chris (1969). British and American Tanks of World War II. New York, NY: Arco Publishing Inc. ISBN 0-668-01867-4
• Doyle, David (2011). Standard Catalog of U.S. Military Vehicles (2nd Edition). Iola, WI: Krause Publications. ISBN 1-4402-2572-9
• Dunn, Walter S. (1995. The Soviet Economy and the Red Army, 1930–1945. Santa Barbara, CA: Greenwood Publishing Group. ISBN 0-275-94893-5
• Green, Michael (2013). Russian Armour in the Second World War: Rare Photogaphs from Wartime Archives: London, UK. Pen and Sword. ISBN 1-4738-2980-1
• Green, Michael (2014). American Tanks and AFVs of World War II. Oxford, UK: Osprey Publishing. ISBN 1-78200-931-0
• Hogg, Ian V.; Weeks, John S. (1980). The Illustrated Encyclopedia of Military Vehicles. Englewood Cliffs, NJ: Prentice-Hall. ISBN 0-13-450817-3
• Hunnicutt, R.P. (2010) Half-Track: A History of American Semi-Tracked Vehicles. Navato, CA: Presido Press. ISBN 0-89141-742-7
• Kinard, Jeff (2007). Artillery: An Illustrated History of it's Impact. Santa Barbara, CA: ABC-CIDO. ISBN 1-85109-556-X
• Ness, Leland S. (2002). Jane's World War II Tanks and Fighting Vehicles. New York, NY: HarperCollins. ISBN 0-00-711228-9
• Rottman, Gordon L. (2012). World War II US Armored Infantry Tactics. Oxford, UK and New York, NY: Osprey Publishing. ISBN 1-78906-083-2
• Zaloga, Steven J. (1994). M3 Infantry Half-Track 1940–1973. New Vanguard. Oxford, UK: Osprey Publishing. ISBN 1-85532-467-9

External links

Wikimedia Commons has media related to 57mm Gun Motor Carriage T48.

• 57 mm Gun Motor Carriage T48
• T48 Gun Motor Carriage – World War II Database
• T48 Gun Motor Carriage – World War II Vehicles