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|Type|| 2 1⁄2-ton 6x6 trucks
5-ton 6x4 trucks
|Place of origin||United States|
|Specifications (U1 Cargo)|
|Weight||9,875 lb (4,479 kg) empty|
|Length||20 ft 11 in (6.38 m)|
|Width||7 ft 4 in (2.24 m)|
|Height||7 ft 3 in (2.21 m) top of cab
8 ft 10 in (2.69 m) overall
|Transmission||5 spd. x 2 range trf. case|
|Suspension||Beam axles on leaf springs|
|236 mi (379.8 km)|
|Speed||45 mph (72 km/h)|
The Studebaker US6 (G630) was a series of 2½-ton 6x6 and 5-ton 6x4 trucks manufactured by the Studebaker Corporation and REO Motor Car Company during World War II. The basic cargo version was designed to transport a 5,000 lb (2,300 kg) cargo load (12 ft (3.7 m) long) over all types of terrain in all kinds of weather. Most of these were exported to the Soviet Union under Lend-Lease by the USA during World War II.
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In 1939 the US Army Ordnance Corps set standards for a 6×6 truck with a 2 1⁄2-ton (2,238kg) off-road payload. Studebaker, Yellow Coach (a GM company), and International Harvester submitted designs. All three were accepted and in production by 1941.
The US6 was manufactured primarily for export under Lend-Lease, of which the Soviet Union would become the largest foreign operator. Production began at Studebaker's truck plant in South Bend, Indiana, in June 1941, and in 1944, REO's plant in Lansing, Michigan, would also begin producing them.
The first Studebaker US6 trucks arrived in USSR in the autumn of 1941. The Soviet Red Army organized a test of eleven 6x6 "Studebekkers" (as they become referred to in the USSR) which took place between July 1942 and May 1943. The results were to enlarge the payload from 2 1⁄2 tons (2,300kg) to 4 tons (3,600kg). In 1945 it was lowered to 3 1⁄2 tons (3,200kg, although on improved roads they could carry up to 5 tons (4,500kg).
A total of 219,882 2 1⁄2-ton (2,268 kg) 6x6 and variant 5-ton (4,536 kg) 6x4 trucks in thirteen variations were built. Studebaker was the primary manufacturer, building 197,678, while REO sub-contracted 22,204 more. REO trucks are identical to Studebakers, but REO only built long wheelbase without winch cargo models.
Engine and driveline
The US6 used a Hercules JXD engine, a 320 cu in (5.2 L) L-head inline 6 cylinder gasoline engine developing 86 hp (64 kW) at 2800 rpm and 200 lbf·ft (271 N·m) of torque at 1150 rpm. A conservative and reliable engine with a compression ratio of only 5.82:1, it could use 72 octane gasoline. This engine was also used in the M3 and later M8/M20 armored cars.
The Timken T-79 transfer case had high and low ranges, a neutral position, and engaged/disengaged the front axle. There was one output shaft forward to the front axle (not used in 6x4s) and two shafts to the rear, one for each rear axle.
Both front and rear axles were Timken split types with a 6.6:1 ratio. The front had ball-type constant-velocity joints, the rears were full-floating.
There were two wheelbases, the short 148 inches (3.76 m), used in semi tractors, dump trucks, and short cargo models, and the long 162 inches (4.11 m), used in tankers, long cargo models, and the U9 chassis cab (measurements are from the centerline of the front axle to the centerline of rear bogie). All models had 7.50-20” tires and dual rear tires. 6x4 models, intended for on road use only, were rated at 5 tons (4536 kg), twice the 6x6’s off road rating. 
The US6 used Studebaker’s civilian truck cab, modified for military use. Studebaker trucks were unique from other 2 1⁄2 trucks built for the war effort because vent windows were included in each door. These windows were separate from the window that rolled down into the door and could be rotated out to help with ventilation.
Studebaker also designed the open-type military truck cab which was featured on the GMC CCKW, but their major customer, the USSR, preferred the closed cab for their generally harsh (cold-weather) climate. While Studebaker's open-type truck cab became the American standard, the US6 returned to the closed-type truck cab after only 10,000 units of the former.
The U1 and winch equipped U2 cargo truck had a short wheelbase and the spare tire mounted behind the cab, allowing a bed only 9 ft (2.74 m) long. These “prime mover” style bodies were not a success, the US6 was to be used primarily for cargo.
The U3/U4 and 6x4 U7/U8 cargo truck had a long wheelbase, which allowed the spare tire to be mounted under a 12 ft (3.66 m) bed. 197,000 trucks with the 12 ft (3.66 m) bed were built.
The U5 gasoline tanker truck had a long wheelbase and a two compartment 750 U.S. gal (2,800 l) tank body. Tanker trucks did not have winches.
The 6x4 U6 semi-tractor was the only tractor in the series. Semi-tractors have limited off-road performance, so the U6 was rated for a 5-ton load on improved roads. For the same reason, they had no front winch.
The U9 chassis-cab had a long wheelbase and no winch. The Katyusha rocket launcher could be mounted on them.
The U10/U11 end dump trucks and the U12/U13 side dump trucks had a short wheelbase. Both had the body mounted on a sub-frame, with the end-type dump having a hydraulic cylinder attached to the chassis with a lever arrangement while the side-type dump had the hydraulic cylinder mounted directly to the truck body.
(U2 with winch)
|Short||20 ft 11 in (6.38 m)||7 ft 4 in (2.24 m)||8 ft 10 in (2.69 m)[c]||9,875 lb (4,479 kg)|
|U3 Cargo (long)
(U4 with winch)
|Long||27 ft 11 in (8.51 m)||7 ft 4 in (2.24 m)||8 ft 10 in (2.69 m)[c]|
|U5 Tanker ||Long||20 ft 11 in (6.38 m)||7 ft 4 in (2.24 m)||7 ft 3 in (2.21 m) [d]||10,585 lb (4,801 kg)|
|17 ft 3 in (5.26 m)||7 ft 3 in (2.21 m)||7 ft 2 in (2.18 m)[d]||8,190 lb (3,710 kg)|
|U7 Cargo (long)
(U8 with winch)
|27 ft 11 in (8.51 m)||7 ft 4 in (2.24 m)||8 ft 10 in (2.69 m)[c]|
|U9 Cab/chassis||Long||7 ft 3 in (2.21 m)||7 ft 3 in (2.21 m)[d]|
|U10 End dump
(U11 with winch)
|Short||18 ft 9 in (5.72 m)||7 ft 4 in (2.24 m)||7 ft 7 in (2.31 m)[e]||10,150 lb (4,600 kg)|
|U12 Side dump
(U13 with winch)
|Short||18 ft 11 in (5.77 m)||7 ft 4 in (2.24 m)||7 ft 7 in (2.31 m)[e]||10,150 lb (4,600 kg)|
- With winch add 1 ft 3 in (0.38 m).
- With winch add 610 lb (280 kg).
- To cargo area tarpaulin bows.
- To top of cab.
- To top of dump body cab shield.
Large numbers of Studebaker US6 trucks were sent into the Soviet Union via the Persian Corridor in Iran under the USA's Lend-Lease programme. The Soviet Red Army found them to be a good platform for Katyusha rocket launchers (more popularly known as "Stalin's Organ"), although it was not to be their main use in the Soviet Union. It fulfilled many roles for the Soviet Red Army, such as pulling artillery pieces and transporting troops, and was renowned for its overall ruggedness and reliability. The truck became affectionately known as the Studer by Soviet troops and was even recognised by Joseph Stalin (the leader of the Soviet Union at that time), who sent a letter of appreciation to Studebaker, in which he thanked them for the superb quality of the US6 for Soviet service. Later on, after WWII, the USSR also copied the design of the Studebaker US6 into the ZiL-151, which, in turn, was replaced by the ZiL-157.
Studebaker US6 trucks were also used by the US military in the construction of the Burma Road (being used for logistics transport on the Burma Road too) as well as on the Alcan Highway in North America.
- List of U.S. military vehicles by supply catalog designation
- List of U.S. military vehicles by model number
- GMC CCKW
- TM 9-807 (1943), pp. 14-16, 138.
- Jeghers (2000), pp. 18-19.
- Crismon & 2001 (184, 328-329).
- Doyle & 2003 (122-124).
- TM 9-807 (1943), pp. 138–139.
- TM 9-2800 (1947).
- TM 9-1807 (1944), pp. 22-23.
- TM 9-1807 (1944), pp. 43–44.
- TM 9-1807 (1944), pp. 84–87, 127–129.
- TM 9-807 (1943), pp. 289-290.
- TM 9-1807 (1944), pp. 177-179.
- TM 9-807 (1943), p. 14.
- TM 9-1807 (1944), pp. 211-216.
- TM 9-2800 (1947), p. 280.
- Doyle, David (2003). Standard catalog of U.S. Military Vehicles. Kraus Publications. ISBN 0-87349-508-X.
- Jeghers (2000). EV Cars Lend-Lease. Tornado.
- "TM 9-807 2 1⁄2-ton 6x6 Truck and 2 1⁄2 to 5-ton 6x4 truck". US War Dept. 1943. Retrieved 24 Feb 2016.
- "TM 9-1807 Power Train, Chassis, and Body for 2 1⁄2 ton 6×6 Truck and 2 1⁄2 to 5-ton 6×4 Truck (Studebaker US6 and US6x4)". US War Dept. 1944. Retrieved 24 Feb 2016.
- "TM 9-2800 Military Vehicles". US Dept. of the Army. 1947. Retrieved 24 Feb 2016.
- Australian Studebakers US6
- Engines of the Red Army
- Studebaker/Reo US6 at Olive-Drab.com
- Studebaker/Reo US6 at The-Bluprints.com
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