Environment Drives Dozer Design

High-flotation undercarriages have grown over the past five years, giving users more flexibility in applications. Caterpillar has gone the farthest in partnering with a machine-control vendor. It is now offering its AccuGrade laser system, factory-installed, on D3, D4 and D5 G-series track-type tractors. Tables: Average Crawler-Dozer Costs 100-hp Crawler-Dozer Competitors

Buying File Gallery: New Holland Construction Dressta Caterpillar Komatsu America Liebherr John Deere Case

The environment affects crawler-dozer choices in two distinctive ways in today's market. First, jobsite conditions determine size, undercarriage and blade choices. Second, and more pertinent to the current state of the machine category, regulations handed down by the Environmental Protection Agency have introduced advances in electronics, which have changed machine control and production.

Dozers move material, and those conditions and applications drive the choices in machine size, undercarriage and blade. Power-angle-tilt blades, also known as PAT, with 6- or even 7-way maneuverability are becoming popular in larger dozers. Smaller dozers, less than 100 horsepower, tend to be used to finish grade, and their bigger siblings rely on brute power to move large quantities of material from place to place.

According to Construction Equipment's 2002 Universe Study, 43 percent of crawler dozers are less than 100 horsepower. Primary life of a dozer averages 11 years, and scrappage occurs at about 19 years. In 2002, the average age of crawler dozers in the machine universe was 8.6 years. And equipment managers have stretched machine life and productivity during the recent economic downturn.

Manufacturers are fielding machines now that take advantage of EPA-engine-emissions mandates to introduce more electronic controls and operating benefits. Add to that the reliability of machine-control systems and today's crawler dozers offer managers much-improved choices.

As manufacturers have implemented engine electronics, they've been able   to provide the plumbing for additional features such as auto shift. "When you can tell that engine that you're in the process of shifting, and it can momentarily make the shift then bring the engine on task, you have the best of both worlds," says Warren Groth, track-type tractor product support engineer for Caterpillar. "You can extend the life of components and give the operator smooth and comfortable changes."

Caterpillar, Komatsu, John Deere and Case have implemented electronic hydrostatic drives, which enable the machine to match the pumps that drive the individual tracks, giving the operator better turning control. "Electronics allow you to absorb full power of the engine so the inside track can slow down," says Rob Warden, Komatsu's product manager, dozers.

Most manufacturers—except Deere—keep hydrostatic transmissions to the smaller machines, usually cutting off at 100 horsepower. Larger machines typically require higher levels of torque in order to move loads, and the standard there is still direct-drive powershift transmissions.

The other technological boon for dozers is in machine-control systems, specifically blade control. Laser- and satellite-based systems have reached such levels of acceptance and accuracy that end-users report substantial savings in costs and improvements in productivity.

These successes include some applications that hadn't been accurate with staking, such as fine-finish grading. Although motor graders aren't in danger of being replaced, properly equipped dozers can do the fine-finish work in some applications, such as house pads.

"You can go from dirt to finish with a crawler with blade control," says A. John Holmes, John Deere's product sales consultant for crawlers. "Mainly, you reduce transportation and maintenance [of the grader], and you reduce the number of operators."

Caterpillar and Komatsu have teamed up with specific suppliers to offer grade-control systems: Caterpillar with Trimble and Komatsu with Topcon. Komatsu is in the "infancy of the alliance," says Warden. Caterpillar has formed a joint venture with Trimble, called Caterpillar Trimble Control Technologies. This company supplies components to both Cat and Trimble. Caterpillar has designed its AccuGrade Laser Grade Control System and is factory-installing it on the D3, D4 and D5 G-Series track-type tractors.

Both manufacturers say the reason they partner with one supplier is to make it easier to install such systems on their machines. "We wanted to fully integrate a blade-control system into our machine," says Caterpillar's Groth. "The best way was to go with a selected company so we could best integrate their product and our tractor."

Cat customers who use different grade-control suppliers will have to rework the machine, Groth concedes, but it will still take less time to install because the hydraulics and electronics have already been made ready.

Other dozer manufacturers try to make their machines control-ready, as well, leaving the vendor choice fully in the end-user's hands. Deere, for example, manufactures its GPS-ready dozers with open power connections in the fuse block and well-protected hydraulic control valves.