High-Stability Rotary Actuator of Sandvik DD2710 in Sweden

The rotary actuator on the Sandvik DD2710's boom positions the feed beam in its rotational axis—the angular orientation that determines whether the drill holes in a face round are correctly angled for the blast design. At Boliden's Garpenberg underground mine, where the silver-zinc ore veins dip at 65–75 degrees and development headings must follow the vein geometry rather than cutting across it, the rotary actuator's angular positioning accuracy determines whether the blast round actually follows the vein or drifts into waste rock. A 2-degree angular error on the outermost contour holes produces 0.3–0.5 meters of positional error at 5-meter hole depth—enough to put contour holes outside the designed blast envelope.

The DD2710 rotary actuator is a hydraulic vane-type actuator that converts hydraulic flow into angular displacement of the feed beam mounting face. Its rotational stability—the ability to hold a set angular position against the percussion reaction force transmitted back through the feed beam—depends on the actuator's internal seal condition. When the actuator's internal seals allow bypass between the high and low pressure chambers, the feed beam drifts from its set position during percussion, producing angular hole deviation that accumulates from the first blow to the last.

Rotary Actuator Performance and Maintenance for DD2710

Garpenberg's drill operators perform a 30-second angular hold test at each face setup—apply percussion at the steepest required angle and observe the feed beam angle indicator during the first 3 holes. Angular drift of more than 0.5° during this test triggers an actuator inspection before the face round continues. The test takes less than 3 minutes and has eliminated the 'crooked round' incidents that previously required re-drilling correction holes. HOVOO supplies DD2710 rotary actuator seal kits and rebuild components. References at hovooseal.com.