Designed by Allis Chalmers on the chassis and drive train of the M2 Light Tank, the 18-ton M4 High Speed Tractor was a prime mover for the U.S. Army during World War II. It was tasked with moving artillery, in particular 3-inch and 90mm anti-aircraft guns, 155mm guns, and 8-inch and 240mm howitzers. Built as a "crawler" and equipped with a 6-cylinder, water-cooled engine, the M4 could travel cross-country through swamps and sand, or on the highway at speeds up to 33 mph. Over 5,500 M4s were built between 1942 and 1945, with many remaining in service into the 1960s. Created in 1943, this official TM 9-785 Technical Manual reveals a great deal about the M4's design and capabilities. Intended as a manual for those charged with operation and maintenance, this manual shows many aspects of its engine, cooling, power, drive train and other systems. 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.