Caterpillar has been testing a trolley assist system, an onboard mechanism that allows a haul truck to tap into an overhead power source, that reduces diesel engine emissions on electric-drive trucks. The system is now available as a retrofit kit for the 795F AC truck. The company says the design is also compatible with Cat 794 AC, 796 AC, and 798 AC units.
Caterpillar tested the system for two years in Boliden’s Aitik mine in Sweden.
“The Cat trolley assist program at Aitik have been a real success story,” said Jonas Ranggard, a program manager at Boliden, in a prepared statement. “Availability has been high despite the arctic conditions, and we’ve had good support from Caterpillar and all other partners involved. There are few projects that can show both environmental and productivity improvements of this magnitude. This is why Boliden has decided to expand the trolley infrastructure in Aitik and equip its entire 795F AC truck fleet with trolley assist systems.”
The trolley system significantly reduces diesel engine emissions at the mine via substitution of electricity during the most demanding part of the truck work cycle. The pilot program used the trolley system to power a 795F AC hauling 337 metric tons on a 10-percent grade as it climbed the ramp out of the pit. According to Caterpillar, the trolley saved up to 40 liters of diesel fuel per kilometer of trolley line. Fuel and engine costs are reduced by more than 90 percent while the truck is on trolley, it said.
The trolley system also boosts productivity. Operating with trolley assist, speed-on-grade increases as much as 100 percent versus diesel-only mode. Using trolley, a loaded 795F can run at 28 kph on a 10-percent physical grade with solid haul road conditions.
Eric Ruth, electrical senior product team leader with Caterpillar, said in a statement:
“We thank Boliden for their work in demonstrating the capabilities of the Cat trolley assist attachment. The benefits of trolley can be significant in the right conditions, and we would be pleased to discuss site-specific scenarios with customers. We feel that trolley assist can play a role in achieving mining companies’ greenhouse gas reduction goals. Simultaneously, trolley assist boosts productivity by increasing speed-on-grade.”