Caterpillar D7E: World’s First Hybrid Bulldozer
As ironic as it is, the heavy machinery used for large scale earthscaping projects can hardly be considered environmentally friendly. The D7E manufactured by Caterpillar, however, may be able to change that perception.
The Caterpillar D7E is an electrically driven dozer that uses a traditional 9.3 Caterpillar engine to drive an oversized generator. By designing the generator to produce maximum power at low engine speeds, the internal combustion engine can remain at a low RPM range without a drop in power. As compared to a previous model which operates between 1600 and 2200 RPMs, the new D7E provides maximum power between 1500 and 1800 RPMs. Fewer cycles per minute equates to more operating time per gallon of fuel. Caterpillar has said this drivetrain has provided a 25% jump in fuel economy when compared to a Caterpillar 9.3 liter engine driving a powershift transmission.
The electric drive system also reduces the amount of time it takes to move material. When field testing the D7E, engineers found it was able to move an average of 330 cubic yards in an hour. At the same time it was burning 6.6 gallons of diesel fuel. The average dozer is able to push about 300 yards per hour while burning 7.7 gallons of fuel.
Between the fuel savings and increased productivity, a single D7E could save companies thousands of dollars over the course of a year. Given the lifetime of the average dozer, the savings are substantial.
The D7E was also designed to easily accept aftermarket accessories. Not only will this increase the ease of moving from one job site to another, it will also make the D7E a more versatile tool that will be able to fit the needs of nearly every operator.
In fact, Caterpillar was recently presented with the Environmental Protection Agency's Clean Air Excellence Award. According to the tests performed, by using the electric drive system the D7E is able to reduce the emission of some gasses by as much as 51%. A full listing is available on the D7E website.
Caterpillar is currently working to expand the electric drive system to other machines.