In 1975, the single engine Caterpillar 633D Elevating Wheel Tractor-Scraper with an all-new tractor design, was introduced as a replacement to the Caterpillar 633C.

Powered by a Caterpillar 3408T turbocharged diesel engine providing up to 450 HP at the flywheel. Equipped with an 8-speed transmission, the Caterpillar 633D is capable of top speeds of up to 30 MPH. The integrated cushion hitch absorbs shocks from haul roads, allowing for higher speeds and a faster cycle time. With 13 flights, the elevating scraper is equipped with a variable speed torque converter which matches ground speed to loading conditions.

Introduced in 1979, the Caterpillar 639D Elevating Wheel Tractor-Scraper was based on the Caterpillar 633D single engine Elevating Scraper. With a turbochraged 3408T diesel engine in the tractor and a 3306T diesel engine at the rear, the Caterpillar 639D is capable of producing 700HP at the flywheel.

The ejection system, which is unique to both the Caterpillar 633 & 639D Elevating Wheel Tractor-Scraper, allows the entire floor to pivot back and up, away from the fixed cutting edge. A fully articulated gooseneck allows for 90° steering in either direction, resulting in maximum maneuverability.

Specification highlights:

• Engine 1 (633D & 639D Tractor): Caterpillar 3408T Diesel Engine
• Engine 2 (639D Scraper): Caterpillar 3306 Diesel Engine
• Net Power: 450 - 700 hp
• Maximum Travel Speed: forward: 33 -38mph
• Heaped Capacity: 34.1 yd3