Track-type tractors with elevated sprocket undercarriage hit 175,000 units produced
Caterpillar has announced that its medium high-drive bulldozers hit the production milestone of 175,000 units in May, 35 years after the equipment giant expanded its elevated sprocket undercarriage concept to the medium dozer or track-type tractor (MTTT) line.
Cat celebrated the milestone in May by producing three commemorative units of its H-Series dozer, a machine it says is still unique for the 130-350hp dozer class. The high drive design Cat introduced in 1985 conformed to the ground better, improving durability, serviceability and performance compared to low-drive and oval track designs, said the manufacturer.
A statement from Caterpillar said the Cat D4H, D5H, D6H and D7H dozer models were the first to feature the high drive design while the D8L model was added to the family in 1987. “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,” said the statement.
According to Wes Holm, chief engineer, Caterpillar medium tractor products, one of the original taglines to promote the early high drive tractors was ‘Beyond Known Capabilities,’ because these units set a new standard for efficiency, productivity and ease of operation.
“With our next generation medium dozer line, which includes the new D5, D6 and D7 models, we continue to push these envelopes through adaptation of technology to drive productivity and efficiency to another level,” Holm added.
According to Cat, with travel and gathering restrictions due to the Covid-19 pandemic, the company cancelled in-person celebrations to mark the historic 175,000-unit milestone. 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.
The first two commemorative units were Cat D6 XE electric drive dozers, featuring a sleek dark grey-and-black paint scheme. The third unit, a D6 dozer with four-speed, fully automatic transmission, is finished in traditional Cat yellow with special black tracks and blade.
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. Cat added that It boasts a strong yet light structure, providing optimum machine balance for grading without the need for a rear implement or counterweight.
Long-time Caterpillar customer, Goodfellow Bros. of Washington state in the USA received one of the D6 XE units. Holt Cat of San Antonio, Texas, took possession of the second commemorative D6 XE dozer while the commemorative D6 dozer was shipped to Canadian dealer Finning Cat, where it was sold to Midwest Pipelines Inc., based in Alberta.
The Cat D6 and D6 XE dozers are manufactured exclusively in East Peoria in Illinois, USA, and in Grenoble, France, along with other models in the medium dozer line.