The new Bucyrus 816C and older Un-A-Hauler models are used at Knight Hawk’s Prairie Eagle and Royal Falcon underground mines in Illinois.

Knight Hawk production superintendent Dale Winter has taken advantage of the flexibility of battery face haulage by operating three to five haulers behind the continuous miner based on the distance from the feeder breaker. He has also found flexibility when driving deep rooms off sections and perimeter mining.

At the new Royal Falcon mine, prior to the conveyor belt being installed underground, the 816C Un-A-Hauler hauled coal to the outside pit area, approximately 1000ft one way in severe bottom conditions.

The unit, which Bucyrus says has a 25% larger payload capacity than its competitors, features true tracking and vertical articulation.

“The true tracking feature and high ground clearance were critical when negotiating the bad bottom conditions,” Winter said.

“The true tracking also improved tyre life by eliminating tyre scuffing when the unit was turned left or right.”

The true tracking design positions the driving wheels equidistant from the articulation pivot allowing the rear wheels to follow in the exact path of the front wheels.

Bucyrus said with this feature, losses in available traction power associated with wheel scuff that is common to trailer style articulation are eliminated.

In addition to increasing power, the true tracking feature also helps in obstacle avoidance since the hopper section of the vehicle follows within the same tyre path of the tractor section.

True tracking geometry together with a 120-degree total steering angle allows for a 90-degree turn in a 16ft (5m) roadway.

The vertical articulation of the 816C has been enhanced by aligning the articulating cylinders with the line of action required to raise and lower the frame of the vehicle to allow variation of the angle of approach or departure.

Bucyrus said this feature allows the operator to raise the trailer to interface with the feeder breaker when discharging the payload. The orientation and placement of the cylinders provides easy access for cylinder, pin or hose replacement.

The hauler also features a HiPAC 10 control system which drives both the motor traction and the hydraulic systems in addition to providing the operator with machine management information.

The HiPAC 10 VFD is a DC to AC variable frequency inverter control that drives higher performance AC electric motors, operating 11% more efficiently than conventional DC motors.

Bucyrus said this means loaded tram speeds can be increased up to 8km per hour (5mph) and more coal can be hauled per battery charge. AC motors also eliminate the need for DC commutators and brush riggings, cutting down operating costs and downtime.