A 600-hp diesel rear dumper for off-highway use has been developed by Autocar in 1957. Engineered for 40-ton payloads, it will travel up to 33 mph (ca. 53 km/h). It is powered by a 12-cylinder, V-type turbocharged Cummins diesel. This engine has previously been used only in locomotives and as a stationary power plant. It is rated at 600 bhp at governed speed of 2100 rpm.
The new dumper is designated as the AP-40 and is the third model in the AP line to be introduced in 1957. It is more than 13 ft (3.96 m) high, 31 ft (9.45 m), 10 in. long and is equipped with a 27-cu yd body. Adaption of the engine to the AP-40 was made possible by recent development of a transmission, the Fuller R-1550, rugged and flexible enough to efficiently utilize the power developed.
Another engineering achievement is an all-welded, box-construction frame of one-inch carbon steel designed to resist the torques encountered under severest off-highway conditions. An offset-mounted cab, engineered for driver safety and comfort, has the adjustable steering column introduced in the AP-25. Set-back, wide-track front axle provides maximum maneuverability.
The AP-40 drives on all four wheels in the tandem rear. If either set of wheels losses traction, an air-powered lock applied on an interaxle differential by the driver from the cab, blocks out torque loss, permitting the other axle to continue driving. Gross weight of the AP-40—with 40-ton payload—is 85 tons.