Mack NO 7½-ton 6x6 truck

{{Infobox weapon

|name=Mack NO series

| image= Mack NO-6.JPG

| image_size = 300

|caption=Mack NO-6 truck; Overloon War Museum, Netherlands

|origin={{flagu|United States|1912}}

|type=7 1/2-ton (6,803kg) 6x6 Prime mover

|is_vehicle=yes

|service=

|used_by=

|wars=

|designer=

|design_date=

|manufacturer=Mack Trucks

|production_date=1943–1945

|number=2,050 (total all models)

|variants=NO2, NO3, NO6, NO7

|spec_label=NO7{{cite web|url=https://www.scribd.com/doc/188375301/TM-9-2800-1947|title=TM-9-2800-1947 Military Vehicles|publisher=US Dept. of the Army|date=27 October 1947|access-date=31 December 2014}}

|weight={{convert|29,103|lb|abbr=on}} empty

|length= {{convert|24|ft|8|in|m|2}}

|width= {{convert|8|ft|6|in|m|2}}

|height={{convert|10|ft|4|in|m|2}}

|crew=

|armour=

|primary_armament=

|secondary_armament=

|engine= Mack EY

|engine_power={{convert|159|hp|kW|abbr=on}} at 2,100 rpm

|transmission=5 speed dual range transfer case

|suspension=Beam axles on leaf springs

|fuel_capacity={{convert|160|USgal|L|abbr=on}}

|vehicle_range={{convert|400|mi|km|1|abbr=on}} on road

|speed={{convert|32|mph|abbr=on}} on road

}}

The Mack NO {{frac|7|1|2}}-ton 6x6 truck 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.{{cite book|last=Vanderveen|first=Bart|title=A Record of Military Macks in the Services and Beyond|publisher=After the Battle|series=Wheels & tracks|year=1998|isbn=1-870067-09-6|pages=79–87}} Its G-number was (G-532).

History

In 1940, Mack Trucks started the development of a wheeled artillery tractor for the U.S. Army, with an off-road payload of {{frac|7|1|2}} tons (6,803 kg), to tow the 155 mm gun, the 8 inch howitzer, the 8 inch gun, and the 240 mm 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 240 mm 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.{{cite book|last=Doyle|first=David|title=Standard catalog of U.S. Military Vehicles|year=2003|publisher=Kraus Publications|isbn=0-87349-508-X|pages=213–215}}

The models NO-4 and NO-5 were prototypes of heavy salvage vehicles, equipped with a Gar Wood crane which could swivel to the left and right. Neither model was put in production.{{cite book|last=Ware|first=Pat|title=The World Encyclopedia of Military Vehicles|year=2010|publisher=Lorenz Books|isbn=978-0-7548-2052-9|page=241}}

Description

File:Mack NO.JPG

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 {{convert|707|cuin|L|1|abbr=on}} ; generating {{convert|159|hp|kW|abbr=on}} at 2100 rpm and {{convert|534|lbfft|0|abbr=on}} 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).{{cite web|url=https://www.scribd.com/doc/156705972/TM-10-1679-MACK-NO02-3-6|title=TM-11-1679 Maint. manual for Mack Models NO2, 3 & 6 7 1/2-ton, 6X6, Prime Mover|publisher=US Dept. of the Army|date=April 1943|access-date=11 December 2014}}

Traction was in all six wheels (6x6), with 14.00-24 tires. The empty weight of the vehicle was {{convert|29,103|lb|abbr=on}}, and {{convert|44,453|lb|abbr=on}} fully loaded.

The gas tanks were located on both sides of the vehicle, with a total capacity of {{convert|170|USgal}}. At the front of the vehicle a Garwood winch was installed with a pulling capacity of {{convert|40,000|lb|abbr=on}}. It could be used to assist in placing the gun, or to help moving the vehicle if it was stuck.

The cargo area was {{convert|11|ft|m|2|abbr=on}} long by {{convert|8|ft|m|2|abbr=on}} wide and could carry {{frac|7|1|2}} tons (6,803 kg) of cargo. Starting with the NO-2 model, at the rear of the cargo compartment a small crane was installed to assist in placing the gun. The maximum towed load of the vehicle was 50,000 lb (22,680 kg){{cite book|last=Doyle|first=David|title=Standard Catalog of U.S. Military Vehicles, 2nd Edition|year=2003|publisher=Krause Publications|isbn=978-0873495080|page=213}}