New era of mine haul truck giants

Diesel Progress North American Edition, March, 1999 by Mike Mercer

After Komatsu unveiled the 930E, Liebherr developed the T282 truck, which was designed using the company's load management philosophy. This design principle, focusing primarily on the mainframe, front suspension arrangement, dump cylinder attachment and rear axle attachment, mandates how loads are transferred into the mainframe from the running gear attachments, and provides for reduction and control of redundant structures.

According to Liebherr, the design of the T282 was approached from the standpoint of utilization of existing proven concepts to create a new product, not stretching an existing product to meet the market need. In addition, the design criteria for the T282 included the requirement that the hauler envelope and handling performance be consistent with existing and planned mine infrastructure.

"The combination of Liebherr's load management philosophy for the design of the mainframe, axle box and dump cylinder attachments coupled with the new technologies of drivetrain systems are what make producing over 300-ton trucks such as the T282 a reality," said Francis Bartley, Liebherr's engineering manager for research and development.

Clearly one of the most intriguing of all the new giants is the new Caterpillar 797 haul truck, which will be commercially available in 2001. The vehicle was recently introduced at the company's proving grounds near Tucson, Ariz.

The truck is powered by Cat's 24-cylinder 3524B long-stroke diesel engine, which features electronic unit injection, an ADEM II electronic controller, aftercooling and four single-stage turbochargers. The engine is rated 3400 hp gross at 1750 rpm.

The truck has a standard capacity of 290 cu.yd., a designed operating weight of 1,230,000 lb. and a capacity of 360 tons. The truck will ride on 55/80R63 tires.

True to its roots, Caterpillar's 797 truck will use a mechanical drivetrain, with all of the major components designed and built by Caterpillar.

"We have expended an awful lot of research in the development of the 797," said Dave Monroe, sales manager Caterpillar mining trucks. "We chose mechanical for the 797 because we know we can do a better job with that system than we could with the a.c. diesel electric system.

"As the technology changes in the future our direction may change, but for now, mechanical is the best direction for Caterpillar."

More information on Cat's new haul truck will be included in an upcoming issue of Diesel Progress.

Cat's current product line incorporates eight haul truck models, with capacities from 40.6 tons to 240 tons.

"How large will the trucks get is anybody's guess at this point," said Monroe. "The next stage of truck will have the same hurdles to get over. Those hurdles are a lightweight, high-speed diesel engine with adequate horsepower, the ability to get the power to the ground through a drive system and the tires to carry the load."

"In addition to the hardware side of the issue, a different aspect to consider is that the economic viability of going into the marketplace becomes more challenging along with the technical issues," said Pete Holman, Caterpillar senior corporate mining consultant. "As the size of the trucks increases, fewer numbers are needed to do the same amount of work and mechanical availability can be key regarding economics and viability of these very large trucks. Strength of the haul roads will be more important with the larger, heavier trucks and that will have a major impact on truck economics in certain locations.