According to Caterpillar, the new Cat trolley assist system for Cat electric drive mining trucks can help mining companies to reduce carbon emissions, lower fuel and engine costs, and boost speed-on-grade for greater productivity.

The Cat trolley assist retrofit kit is currently available for the 795F AC truck, and the trolley design is compatible with the three other Cat electric drive mining trucks - the 794 AC, 796 AC and 798 AC.

The commercial introduction of Cat trolley assist comes at the conclusion of a nearly two-year pilot project conducted with four 795F AC trucks using 700m of electric trolley line at Boliden's Aitik mine in Sweden.

"The Cat trolley assist programme at Aitik [has] been a real success story," said Jonas Ranggård, a program manager at Boliden. "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."

Eric Ruth, electrical senior product team leader with Caterpillar, commented: "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. In fact, testing at Aitik mine has shown that a 795F AC equipped with trolley assist is the most powerful mining truck in the world!"

Based on the pilot project at Aitik, Caterpillar stated that the trolley system can significantly reduce diesel engine emissions at the mine via substitution of electricity during the most demanding part of the truck work cycle. Powering a 337t-payload 795F AC via trolley on a 10% grade as it climbs the ramp out of the pit can save up to 40L of diesel fuel per kilometre of trolley line. Fuel and engine costs can also be reduced by more than 90% while the truck is on trolley.

In addition, the trolley system can boost productivity. Operating with trolley assist, speed-on-grade can increase as much as 100% versus diesel-only mode. Using trolley, a loaded 795F can run at 28km/h on a 10% physical grade with solid haul road conditions.

The Cat trolley system is fully machine integrated, which the company said brings the benefits of optimised performance and system serviceability to the 795F AC. Caterpillar's higher voltage truck and trolley system is designed to bring advantages through lower infrastructure capital costs and lower power distribution maintenance costs.

Other advantages come from the rugged Cat pantograph, which is designed to deliver superior uptime and reduced repair costs. A quick-drop feature can also help to protect the overhead trolley lines.