In 1985, Caterpillar expanded its elevated sprocket undercarriage concept to its medium track-type tractor (MTTT) line with the launch of the H-Series models.
Still unique to this day for the 130 to 350 hp (100 to 250 kW) dozer class, the high drive design conformed to the ground better, improving durability, serviceability and performance compared to low-drive and oval track designs. The Cat® D4H, D5H, D6H and D7H dozer models were the first to feature the high drive design, and in 1987, the D8L model was added to the family. In addition to bringing many of the same large dozer advantages to the medium line, the elevated drive sprocket allowed movement of the front and rear track idlers. This helped to fine-tune machine balance and ground pressure for specific applications more easily than oval track machines. For the first time, variable pitch angle tilt (VPAT) blades were made available to high drive dozers with the D4H and D5H models for finishing jobs faster by grading at higher speeds.
Thirty-five years later, Caterpillar celebrated the success of the elevated sprocket design in the medium dozer class by producing three commemorative 175,000 units in May 2020. With travel and gathering restrictions resulting from the ongoing coronavirus pandemic, Caterpillar cancelled in-person celebrations to mark the historic 175,000-unit milestone for its medium dozers. However, three customers took possession of the commemorative units, which feature special decals on the fenders denoting the 175,000-unit milestone. The 175,000 image appears inside the cab as well, where it is embroidered on the headrest and printed on a plaque denoting each unit’s limited-edition status.
Symbolic of the medium dozer line’s long history of innovation, the Cat D6 XE is the world’s first electric drive dozer to offer the elevated sprocket design. It boasts a strong, yet light, structure, providing optimum machine balance for grading without the need for a rear implement or counterweight. Integrated Cat GRADE technologies, such as standard Slope Assist and available Cat GRADE with 3D, help to increase overall jobsite productivity by up to 50 percent. Offering up to 35 percent improved fuel efficiency, the dozer features a durable design with updated components, long service intervals, and extended scheduled maintenance to reduce service and maintenance costs by up to 12 percent. Source