Caterpillar introduced its newest large mining truck, the 291-tonne (320-ton) 794 AC, at MINExpo International in September 2016. The truck uses a combination of proven designs, such as a chassis that has accumulated about 18 million operating hours and an AC powertrain that has racked up 4 million hours.
“The 794 has a fully integrated Cat® electric drive system — engine, drive train, software controls, everything,” says Performance Manager John Ingle. “That means we can have better efficiency, and utilize features like Cat oil-cooled disc brakes on all four corners. All these features come together in one truck that is entirely supported by Caterpillar and Cat dealers.”
Today, after five years of extensive field testing at key mines, 794s are operating in four countries —working in applications ranging from deep pit copper in the western United States to coal and copper in South America.
“Field testing also included comparisons against trucks in this size class that were built by other manufacturers, says Ingle. “These comparisons have helped miners recognize the 794 AC’s advantages over existing trucks in its class — like substantial improvements in their performance and cost per ton.”
Miners who evaluate the trucks are discovering a number of ways the Cat 794 AC outperforms the most popular competitor in the 291-tonne (320-ton) electric drive truck class:
- True 290 tonnes (320 tons). Often, when competitive trucks are configured to match the application and the 794 performance, their empty weight is heavier than promoted. The weight-efficient 794 delivers more payload for a given rated Gross Machine Weight (GMW).
- Nearly 1 kph (.6 mph) faster speed on grade. During trials in the field, the properly-loaded 794 AC operating on an 11 percent grade consistently demonstrated a speed advantage over the competition. This advantage was attributed to the competitive truck’s higher field weight and other factors. This faster speed on grade can result in a significant production advantage on an uphill haul.
- Robust service and park brakes. As Ingle points out, oil-cooled wet disc brakes with integrated park brakes are a hallmark of Cat design. This means that beyond the superior continuous retarding dynamics of the 794, operators are also comfortable with capabilities of the truck’s wet disc brakes to provide added control.
- 19 percent higher stall torque. With about 22 000 kg (48,500 lbs) more stall torque than competitive trucks, the 794 AC delivers higher performance in soft underfoot conditions.
- 40 percent more retarding power. With 4086 kW (5480 hp) of retarding power — about 1200 kW (1600 hp) more than the competition — the 794 can deliver faster cycle times, plus operators can work more confidently on steep downhill hauls.
- When the Cat 794 AC and its competitors are identically configured, the competitive truck measures considerably higher than its specified weight. The result is that the competitive trucks field a reduction in payload or a decrease in cycle times.
- 1,275 CFM more cooling capacity. The 794 AC features an efficient hydraulic variable-speed motor, while the top competitive truck uses a mechanical alternator-driven blower. The additional cooling capacity offered by the 794 AC allows optimum cooling even at idle, which helps extend the life of key components and reduces total owning and operating costs of the truck.
- Easier maintenance. The 794 AC offers a number of serviceability enhancements, like ground level filters, engine service bay walkways, and the brushless AC motor that powers the grid. It requires no regular maintenance, unlike the competitive machine’s DC motor, which requires two hours of maintenance to change the brushes.
These and other advantages add up to a solid truck that miners can depend on, says Ingle. “Mines running the 794 are confirming the truck is built with proven iron and able to go toe-to-toe with the competition — and win,” he says.
“Now mines using trucks in this size class have a proven Caterpillar option when it’s time to replace their aging 320-ton fleets,” Ingle says. “They don’t have to adjust their operations to a different sized truck or a different drive system.”