Conexpo 2008 exclusive: Cat launches D7E electric drive dozer

Caterpillar is claiming a world first with an electric drive dozer, the D7E which will be in production next year.

The unit uses a traditional diesel engine but instead of powering the tracks through a torque converter, it drives an electric motor and two hydraulic pumps. Two 480V motors coupled by three sets of planetary gears power the tracks, and means the transmission has 60% fewer parts than normal.

Without the losses in the torque converter, Cat said the machine is 10% more productive, despite being almost 4kW down on power. Running at lower - and more constant - speed also improves economy and the electric motors retain their high efficiency across a wide load/speed range, resulting in a 20% cut fuel consumption and 25% more metres per gallon.

Other advantages include a 50% increase in steering performance and electric powered air conditioning and water pump removing the need for belts on the engine. The machine also gets a new, single pillar cab providing ‘unrivalled’ visibility. Noise levels are reduced by 50%. 

According to Cat the System 1 undercarriage, a doubling of hydraulic oil life and 4,000hr service life - of the oil cooling the alternator and motors - will reduce service costs considerably.