|Mack NO series|
Mack NO-6 truck; Overloon War Museum, Netherlands
|Type||7 1⁄2 ton (6,803kg) 6x6 Prime mover|
|Place of origin||United States|
|Number built||2,050 (total all models)|
|Variants||NO2, NO3, NO6, NO7|
|Weight||29,103 lb (13,201 kg) empty|
|Length||297 in (7.54 m)|
|Width||103 in (2.62 m)|
|Height||124 in (3.15 m)|
|Engine||159 hp (119 kW)|
|Transmission||5 speed x 2 range trf. case|
|Suspension||Beam axles on leaf springs|
|400 mi (643.7 km)|
|Speed||32 mph (51 km/h)|
The Mack NO was a heavy 6x6 cargo truck designed in the 1940s by the American manufacturer Mack Trucks. It was used by the U.S. Army as an artillery tractor for heavy artillery during and after World War II. The official U.S. Army designation was: Truck, 7 1/2 ton, 6x6, Prime Mover. It’s G-number was (G-532).
In 1940 Mack Trucks started the development of an artillery tractor for the U.S. Army, with a payload of 7 1⁄2 tons (6,803kg), to tow the 155mm “Long Tom” field gun, the 8 inch howitzer, and the 240mm howitzer. A contract for the production of the vehicle was awarded in September 1940, and in January 1942 a vehicle of the NO-1 type towed the first 240mm howitzer carriage from the Bucyrus plant in South Milwaukee, Wisconsin to the Aberdeen Proving Ground test facility.
The NO-1 was the first in a series of five very similar prime mover vehicles. The NO-2 differed in details, among them a canvas cabin roof (the NO-1 had a metal roof) and the winch behind the front bumper (above the bumper in the NO-1). A total of 403 units of the NO-2 were delivered in 1943. The next prime mover models, which marginally differed from the NO-2, were the NO-3 and NO-6. A total of 1,097 units of these were ordered and delivered in 1943 and 1944. The last of the series was the NO -7 model, of which 188 were delivered in 1944 and 362 in 1945. Several NO-7 were provided after the war to the European armies being rebuilt, including those of United Kingdom, France, Belgium and Netherlands.
The vehicle had a typical configuration, with a hooded front engine behind which was a large driver cabin that could seat five soldiers, and a rear cargo area.
The engine was a Mack EY, 6-cylinder gasoline with a displacement of 707 cu in (11.6 L) ; generating 159 hp (119 kW) at 2100 rpm and 534 lbf·ft (724 N·m) at 800 rpm.  The transmission had 5 gears forward and one reverse. The installation of a transfer case with an additional reduction gear allowed high and low gearing (5F1Rx2).
The gas tanks were located on both sides of the vehicle, with a total capacity of 170 US gallons (640 l; 140 imp gal). At the front of the vehicle a Gar Wood winch was installed with a pulling capacity of 40,000 lb (18,000 kg). It could be used to assist in placing the gun, or to help moving the vehicle if it was stuck. 
The cargo area was 11 ft (3.35 m) long by 8 ft (2.44 m) wide and could carry 7 1⁄2 tons (6,803kg) of cargo. Starting with the NO-2 model, at the rear of the cargo compartment a small crane was installed to assist in in placing the gun.
|Type||Model||Years Produced||Number Built|
|Artillery tractor||NO-3 & NO-6||1943 to 1944||1,097|
|Artillery tractor||NO-7||1944 and 1945||550 (188 + 362)|
- List of U.S. military vehicles by supply catalog designation (G-532)
- List of U.S. military vehicles by model number
- Mack Trucks
- Vanderveen, Bart (1998). A Record of Military Macks in the Services and Beyond. Wheels & tracks. After the Battle. pp. 79–87. ISBN 1-870067-09-6.
- Doyle, David (2003). Standard catalog of U.S. Military Vehicles. Kraus Publications. pp. 213–215. ISBN 0-87349-508-X.
- Ware, Pat (2010). The World Encyclopedia of Military Vehicles. Lorenz Books. p. 241. ISBN 0-7548-2052-1.
- "TM-11-1679 Maint. manual for Mack Models NO2, 3 & 6 7 1⁄2 ton, 6X6, Prime Mover". US Dept. of the Army. Apr 1943. Retrieved 11 Dec 2014.
- "TM-9-2800-1947 Military Vehicles". US Dept. of the Army. 27 Oct 1947. Retrieved 11 Dec 2014.
|Wikimedia Commons has media related to Mack NO.|
- Mack NO 7 1/2 Ton 6x6 Truck (G-532); Olive-Drab website (accessed 2014-02-25)