GMC CCKW 2½-ton 6x6 truck

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CCKW
GMC 2 Half-ton 6x6 Truck.jpg
CCKW 353 cargo truck with winch
Type2 12-ton 6×6 Cargo truck
Place of originUnited States
Production history
DesignerYellow Truck and Coach Co.
Designed1941
ManufacturerYellow/GMC Truck and Coach
Chevrolet
Produced1941–45
No. builtGrand Total: ~572,500
including all variants;
CCKW specific: ~518,000
LWB CCKW-353: ~464,000 and
SWB CCKW-352: ~54,000 units
plus ~54,500 non CCKW variants
Variants1939 ACKWX – 2,466 units
C.O.E. AFKWX – 7,235 units
6x4 CCW-353 – 23,649 units
DUKW amphibs – 21,147 units
Specifications (353 Cargo w/winch[3])
Mass8,800 lb (4,000 kg) empty
16,400 lb (7,400 kg) loaded
Length270 18 in (6.86 m)
Width88 in (2.24 m)
Height93 in (2.36 m) to cab
109 18 in (2.77 m) overall

EngineGMC 270 straight-6
91.5 hp (68.2 kW) at 2,750 rpm [1] or 104 hp (78 kW) at 2,750 rpm [2]
Transmission5 spd. x 2 range trf. case
SuspensionBeam axles on leaf springs
Fuel capacity40 US gal (150 l)
Operational
range
300 mi (482.8 km)
Speed45 mph (72 km/h)
Restored CCKW 353 Cargo truck with open cab, machine gun ring, and front-mounted winch

The GMC CCKW, also known as "Jimmy", or the G-508 by its Ordnance Supply Catalog nr,[4] was a highly successful series of off-road capable, 2​12-ton, 6x6 trucks, built in large numbers to a standardized design (from 1941 to 1945) for the U.S. Army, that saw heavy service, predominantly as cargo trucks, in both World War II and the Korean War. The original "Deuce and a Half", it formed the backbone of the famed Red Ball Express that kept Allied armies supplied as they pushed eastward after the Normandy invasion.[5]

The CCKW came in many variants, including open or closed cab, long wheelbase (LWB) CCKW-353 and short (SWB) CCKW-352, and over a score of specialized models, but the bulk were standard, general purpose, cargo models. A large minority were built with a front mounted winch, and one in four of the cabs had a machine-gun mounting ring above the co-driver's position.

Of the almost 2.4 million trucks that the U.S. Army bought between 1939 and December 1945, across all payload weight classes, some 812,000, or just over one third, were ​2 12-ton trucks.[6][7] GMC's total production of the CCKW and its variants, including the 2​12-ton, 6x6, amphibian DUKW, and the 6x4, 5-ton (on-road) CCW-353, amounted to some 572,500 units – almost a quarter of the total WW II U.S. truck production, and 70 percent of the total ​2 12-ton trucks. GMC's total of ~550,000 purely 6x6 models, including the DUKW, formed the overwhelming majority of the ~675,000 six by six ​2 12-ton trucks, and came in less than 100,000 shy of the almost 650,000 World War II jeeps.[8][9][7] Additionally, GM built over 150,000 units of the CCKW's smaller brother, the ​1 12-ton, 4x4 Chevrolet G506, at the same factory.

The GMC CCKW began to be phased out, once the M35 series trucks were first deployed in the 1950s, but remained in active U.S. service until the mid-1960s. Eventually, the M35 series, originally developed by REO Motors, succeeded the CCKW as the U.S. Army's standard ​2 12-ton, 6x6 cargo truck.


Etymology[edit]

The name CCKW comes from GMC model nomenclature:[10]

  • "C", designed in 1941
  • "C", conventional cab
  • "K", all-wheel drive
  • "W", dual rear axles
  • "X", experimental chassis / non-standard wheelbase (first 13,188 units [8])

History[edit]

In 1939-1940 the US Army Ordnance Corps was developing ​2 12-ton (2,268 kg) load-rated 6×6 tactical trucks that could operate off-road in all weather. General Motors, already supplying modified commercial trucks to the Army, modified the 1939 ACKWX – built for the French Army – into the CCKW.[11] The General Motors design was chosen by the Army and went into production at GM'S Yellow Truck and Coach division's Pontiac, Michigan plant alongside 6×4 CCWs. Later they were also manufactured at GM's St. Louis, Missouri Chevrolet plant.[12][13]

Production numbers[edit]

Sources do not precisely agree on the total numbers of CCKWs built by the end of production in 1945. Ware (2010) lists one single number of 562,750 of CCKW trucks, built across all variants – presumably including the amphibian DUKW. More clearly specified numbers are provided by Sunderlin in Army Motors magazine, and by Jackson, using the numbers found in the 1946 revision of the U.S. military's Summary Report of Acceptances, Tank-Automotive Materiel. Sunderlin reports a total of 528,829 of ​2 12-ton 6x6 units (excluding the DUKW) produced by GMC — versus a total of 527,168 accepted by the U.S. Army.[8] Jackson's tabulation of the 1946 U.S. acceptances numbers adds up to 524,873 units, excluding the DUKWs and the ACKWX predecessor models.[9][14] Both of these numbers still include the cab-over engine AFKWX-353 models — leaving a total of some 518,000–519,000 actual CCKW-352 and CCKW-353 units.[8][9] In addition, GMC serial numbers indicate a production of 23,500 of the same bodied 6x4 CCW models, versus 23,649 units accepted by U.S. ordnance.[8]

In any case, GM / GMC built a total of ​2 12-ton, 6-wheeled trucks that was second only to the WW II “Jeep” [11] — and neither Ford nor Willys individually built as many jeeps during the war.

Specifications[edit]

Engine and drive-line[edit]

The CCKW was equipped with the GMC 270 engine, an overhead valve inline-6 with 91.5 hp (68.2 kW) [1] or 104 hp (78 kW) [2] at 2750rpm, and 216 pound-feet (293 N⋅m) at 1400rpm.[1] A 3 2532 in (96 mm) bore by 4 in (102 mm) stroke gave a 269.5 cu in (4.4 L) displacement.[15] This (gasoline) engine was designed for commercial trucks, and was reliable in service.[16]

The transmission was a Warner T93 5-speed with a direct 4th gear and overdrive 5th gear. The transfer case had high and low gears, and engaged the front axle. Originally all axles were a Timken split type, later trucks also used GM "banjo" types.[17][18]

Chassis[edit]

The CCKW had a ladder frame chassis with three driven beam axles, the front on leaf springs, the rear tandem on leaf springs with locating arms. There were two wheelbases, the short Model 352 and the long Model 353. The short, 145 in (368 cm) (Measurements are from the centerline of the front axle to the centerline of rear bogie) was used with a short cargo bed as an artillery prime mover for 75 mm and 105 mm howitzers. All other models used the long 164 in (417 cm) wheelbase. Tires were 7.50-20, brakes were hydraulic with vacuum assist.[16]

Some were fitted with 10,000 lb (4,500 kg) front-mounted winches. A winch added 300 pounds (140 kg) and 14 inches (36 cm).[19]

Some open cab chassis were cut in half behind the cab for air transport. Each half was a load, at the vehicle's destination, the halves were bolted back together.[16][20]

Versions[edit]

Van body with canvas roof and doors in place
Gasoline tanker (750 US gal (2,800 l))
CCKW-353-B2 gun truck with M45 Quadmount on M20 trailer in bed, loading ramps attached to side

Initially, all versions used a modified commercial closed cab design having a metal roof and doors. By 1944 an open cab version, with a canvas roof and doors, was used. This was easier to build, and the roof could be removed to lower the shipping height. 1 in 4 of cabs had a machine gun mounting ring above the co-driver's position.[16]

The CCKW provided a platform for the widest range of bodies on any U.S. military vehicle,[citation needed] with the 12 ft (3.7 m) cargo version being the most common. As steel was more heavily rationed during the course of the war, the steel cargo bed was replaced by a wooden one. Wooden beds proved unsatisfactory and a 'composite' bed with steel sides, framing, and wooden bottom slats was developed.[13] However, the composite bed was still unsatisfactory and the bed design returned to all steel. Standard cargo models had beds with fixed sides and a drop tailgate, as well as folding troop seats.

A standard rectangular van configuration was used in communications, medical, workshop, and many other specialty roles. Special built vans were also used.[21]

Specialized variants[edit]

Many specialized variants of the basic 6×6 CCKW were made, some in small numbers, including some converted in the field. These include:[22]

  • Air compressor
  • Bomb service
  • Chemical decontaminating
  • Chemical handling
  • Dental operating van
  • Dump truck
  • Fire engine
  • Fuel & gas tankers (750 US gal (2,800 l))
  • Fuel & oil handling (660 US gal (2,500 l)), (750 US gal (2,800 l))
  • High lift
  • K-53 radio equip. van
  • K-60 radio equip. van
  • Map reproduction van
  • Ordnance maintenance van
  • Pipeline equipment
  • Ponton bolster
  • Semi-trailer tractor[23]
  • Shop equipment GP repair van
  • Surgical van
  • Water purification van
  • Water tanker (700 US gal (2,600 l))
  • Welder's truck

ACK-353[edit]

The ACK-353 (A for 1939 design, C for conventional cab, and K for all wheel drive) ​1 12-ton 4x4 truck was the smaller brother of the ACKWX, and a predecessor to the Chevrolet G506, competing with the Dodge / Fargo T-203 / VF-400 series, as GM was at that time also trying to clinch the lucrative contract for the standard World War II cargo trucks in the ​1 12-ton 4x4 category.[24]

The ACK-353 was equipped with the new for 1939 GMC 248 engine, an overhead valve, low-deck inline-six with a 3 2332 in (94 mm) bore and 3 1316 in (97 mm) stroke, resulting in a 248 cu in (4.1 L) displacement, producing 77 brake horsepower (57 kW) (net).[25][26] Transmission was four-speed manual, combined with a two-speed transfer-case engaging the front axle for all-wheel drive operation.

The truck rode on a 157 34 in (401 cm) wheelbase, measuring 256 in (650 cm) long, 90 in (229 cm) wide, and 117 in (297 cm) tall – or 89 in (226 cm) with the rear top bows taken down.[26] Tires were 7.50-20, and weight came in at 7,532 lb (3,416 kg). A special feature were the front hubs, designed to take dual wheels in especially challenging terrain.

Fitted with steel GS bodies with fixed sides and troop seats, the trucks were originally ordered under French contract, but ended up in use by the British Army,[26] although some 2,000 units delivered to the French in early 1940 likely fell into the hands of the Nazi Germany Wehrmacht.[27]

ACKWX-353[edit]

The ACKWX-353 (A for 1939 design, C for conventional cab, K for all wheel drive, W for tandem rear axles, and X for non-standard chassis) three-ton 6x6 truck was the direct predecessor from which the CCKW was developed.[28] Fitted with the same 77 brake horsepower (57 kW) drivetrain as the ACK, the trucks weighed 9,856 lb (4,471 kg), and measured 264 in (671 cm) long, 94.5 in (240 cm) wide, and 118 in (300 cm) tall / or 90 in (229 cm) to cab.[29]

GMC AFKWX-353 cab-over-engine

Some 1,000 of the 3-ton 6x6 trucks were originally contracted by France, but – just like the 4x4 ACK trucks – after the defeat of the French, diverted to Britain in 1940. The British however, deemed the trucks unfavorable for use in the war, due to their long wheelbase and lacking power, and diverted them to Russia in turn, in 1941.[28] A total of 2,466 ACKWX trucks were built — both according to GMC's serial numbers, as well as the U.S. Army's acceptance figures.[8]

AFKWX-353[edit]

The AFKWX (A for 1939 design, F for forward cab, K for all wheel drive, W for tandem rear axles, and X for non-standard chassis) 353, a cab over engine, long cargo bed version of the CCKW, went into production alongside it in 1942 at Yellow’s Pontiac plant and Chevrolet’s in St. Louis. Otherwise mechanically identical, its compact cabin design allowed a 15 ft (4.57 m), and later 17 ft (5.18 m) cargo bed to be fitted. Only the first 50 units produced had closed cabs, all others were open. None had a front-mounted winch. The cab over design made engine maintenance difficult. As a result, only 7,235 were built,[30][31] – 2,232 units with the 15 ft. body, and 5,000 of the 17 ft. version.[9]

DUKW in use by American troops in France

CCW-353[edit]

The CCW-353 (C for 1941 design, C for conventional cab, and W for tandem rear axles) was a near identical version of the CCKW-353, that lacked its front-wheel drive, resulting in an officially purely on-road, and therefore 5-ton rated, 6×4 version of the same truck. A beam front axle was used, with the transfer case locked in high range. Of the ~118,000 ​2 12-ton, 6x4 trucks the U.S. built in WW II, GMC contributed 23,649 units of the CCW-353 as standard cargo trucks without winch – almost all of them built in 1942.[32]

DUKW[edit]

The DUKW (D for 1942 design, U for utility, K for all wheel drive, and W for tandem rear axles) — popularly the “Duck” – was an amphibious truck that shared the CCKW's driveline, but had a totally different body and structure than all the other trucks. First produced at Yellow’s Pontiac plant, as demand increased production was added to Chevrolet’s St. Louis plant. The hull, designed by an America's Cup winner, gave the truck respectable sea-keeping capability. A very successful design, 21,147 were built.[33][34][35]

Gallery[edit]

See also[edit]

Notes[edit]

  1. ^ a b c TM 9-2800 'MILITARY VEHICLES' (1947), p. 267–270, 272–279.
  2. ^ a b TM 9-2800 'Standard Military Motor Vehicles' (1943), p. 238–275.
  3. ^ TM 9-801 (1944), pp. 6-9, 16-19.
  4. ^ The U.S. Army Ordnance Corps Supply Catalog designation, 'G-number', or SNL nr. — a group number for ordering parts, based on a Standard Nomenclature List.
  5. ^ Colley (2000).
  6. ^ (Or 5-ton on-road rated)
  7. ^ a b Hyde, Charles K. (2013). Arsenal of Democracy: The American Automobile Industry in World War II. Wayne State University Press. p. 152–154. ISBN 9780814339527.
  8. ^ a b c d e f Sunderlin, Bryce. "THE JIMMY's ANCESTRY – The CCKW in Detail and The Collector's Syndrome" (PDF). Army Motors. Lansing, MI: CCKW.org. pp. 19–22. Archived from the original (PDF) on 4 March 2016. Retrieved 10 April 2019.
  9. ^ a b c d Jackson, David (1 February 2019). "The American Automobile Industry in World War Two – GMC". Retrieved 10 April 2019.
  10. ^ Whitlock (2004).
  11. ^ a b Ware (2010), pp. 238-239.
  12. ^ Crismon (2001), pp. 9, 184, 326, 330-335, 465.
  13. ^ a b Doyle (2010), p. 9.
  14. ^ Summary Report – Tank-Automotive Materiel (1945), pp. 86–102.
  15. ^ TM 9-801 (1944), pp. 6-9.
  16. ^ a b c d Doyle (2003), pp. 108-118.
  17. ^ TM 9-801 (1944), pp. 13-14, 35-39.
  18. ^ Doyle (2010), pp. 9, 10, 20.
  19. ^ TM 9-801 (1944), pp. 17-18, 54-58.
  20. ^ Doyle (2010), pp. 47-55.
  21. ^ Doyle (2010), pp. 78-80.
  22. ^ TM 9-2800 (1947), pp. 267-268, 272-293.
  23. ^ "GMC CCKW Tractor". The G503 Album. Retrieved 8 August 2017.
  24. ^ Doyle, David (2019). Chevrolet G-506 – ​1 12-ton 4x4 Development, Production and Variants in WW2. Branchville, NJ: Portrayal Press. p. 8. ISBN 9780938242062.
  25. ^ Military Light Trucks – Olive-Drab
  26. ^ a b c Vanderveen, Bart (1972). Observer's Fighting Vehicle Directory, WW II. London: F. Warne. ISBN 978-0723214694. Archived from the original on 3 March 2018.
  27. ^ Engines of the Wehrmacht – GMC ACK-353, 1.5-ton, 4x4, Cargo Truck
  28. ^ a b Engines of the Red Army in WW2 – GMC ACKWX-353
  29. ^ Vanderveen, Bart (1972). Observer's Fighting Vehicle Directory, WW II. London: F. Warne. ISBN 978-0723214694. Archived from the original on 3 March 2018.
  30. ^ Doyle (2003), pp. 105-107.
  31. ^ TM 9-2800 (1947), pp. 268-269.
  32. ^ The American Automobile Industry in World War Two – GMC (2-1-2019)
  33. ^ TM 9-801 (1944), pp. 465.
  34. ^ Doyle (2003), pp. 119-121.
  35. ^ Summary Report – Tank-Automotive Materiel (1945), p. 86.

References[edit]

External links[edit]