Fourty years ago, equipped with an elevated drive sprocket and a new undercarriage design, the Cat large dozer was introduced. Caterpillar said the suspended undercarriage with high drive design conformed to the ground better than standard oval tracks, helping to improve machine traction, extend undercarriage life and enhance operator comfort.

Greg Hepler, product manager for large dozers, said: "Caterpillar transformed the track-type tractor with the introduction of the suspended undercarriage with elevated drive sprocket. This innovation, along with a long history of others, enabled Cat large dozers to set the standards for efficiency, productivity and durability. These iconic machines continue to define who we are and play a key role in building a better world."

The current Cat large dozer line includes the D9, D10 and D11 models.

Denise Johnson, Caterpillar group president responsible for resource industries, handed the keys of the 40,000th large dozer to Louis DeLuca, Teck director of supply management, during the ceremony held October 25.

The celebration included employees in Caterpillar's Building SS, where all 40,000 Cat D9, D10 and D11 dozer models have been manufactured.

For more than 10 years, Teck has been one of the top customers in the world for Cat large dozers. The 40,000th large dozer, a 225,000lb (102,058kg) D11T, will operate in the Elk Valley near Sparwood, British Columbia, Canada, where the company produces steelmaking coal at five mines.

"This milestone is important, not just because of the sheer number of Cat machines sold, but also because it represents the many long-lasting and mutually beneficial business relationships established with customers like Teck," Hepler said. "We are honoured to celebrate this achievement with Teck, and we are grateful that their Elk Valley mines have counted on Caterpillar, Cat equipment and their dealer, Finning Canada, to help them reach their production goals since 1992."

Teck's newest D11T will be used for production dozing, dump area support, mining shovel support and haul road development.

The milestone D11T is equipped with a Cat C32 engine, producing 850hp (634kW) and capable of moving up to 900 loose cubic metres of material per hour.

Caterpillar said even in Teck Coal's demanding, high-production application, the efficient powertrain ensures the material is moved at a lower cost per tonne; its rugged mainframe is designed for multiple rebuilds and lowest total cost of ownership.