The Mack Model NR was a heavy truck constructed for military use from 1940 to 1945 by the Mack Manufacturing Corporation of New York U.S.A. The Model NR was mainly used to tow trailers carrying heavy equipment such as tanks and large bulldozers. It was also used to tow heavy field guns. Its wide bogie axles and extra large tires were ideal for desert service, allowing them to "float" on the sand. Many Model NRs were supplied under the Lend-Lease Program to Great Britain, Australia, Russia and other Allied countries. The Mack diesel engine in the Model NR was the result of nearly a decade of development work by the innovative company, which was the first truck manufacturer to produce its own engines. It used the Lanova combustion chamber design. It produced 131 brake horsepower with 519 cubic inches of displacement. It offered a significant improvement in fuel economy, durability, driveability and torque. Mack's long history with the military dates to 1911, when the company began an affiliation with the War Department. During WWI the company supplied trucks to the British, and in fact Mack's famous "Bulldog" nickname was started by Tommys who, when facing daunting terrain, would yell, "Send in the Mack Bulldogs." Created in 1944, this technical manual reveals a great deal about the Mack Model NR's design and capabilities. Originally labeled restricted, this manual was declassified long ago and is here reprinted in book form. Care has been taken to preserve the integrity of the text."