Marginal Column

Overhead, underground

July 2013

 

The Redbore 30 boxhole drill gives access even to hard-to-reach ore bodies. Its direct hydraulic drive makes it compact, light and extremely powerful.

 
 

It goes straight through the ceiling: the Redbore 30 boxhole drill.
Photo: Courtesy of The Redpath Group

Slowly the blind hole drilling head eats its way into the rock. The air is filled with grinding and cracking as it chews ever deeper into the back. The Redbore 30 boxhole drill has a clear mission. It is searching for veins of ore that cannot be accessed without costly development. What’s so special about this concept? It works overhead, drilling upward into the back. This is the first Direct Drive designed by J. S. Redpath for this specific application. This saves expenses for the user, since it is not necessary to drift tunnels above the body of ore. The Hägglunds CA 140-120 direct hydraulic drive by Rexroth makes it possible to drill in this direction. The motor, both short and compact in its dimensions, can be attached directly, even in tight spaces, with the shaft pointing upward.

This means, there was quite a list of requirements for the new drill as developers at J. S. Redpath Limited, in Ontario, Canada, started engineering work. The drill was to occupy as little space as possible while being rugged, delivering great power, and drilling upward into the rock. The same was true for the components. In regard to the drive technology, those requirements are exactly why the choice fell to the compact Hägglunds direct drive hydraulic motor. Redpath’s experience with this motor has been excellent. “The Hägglunds is the proven Cadillac of High Torque Low Speed Hydrostatic Drives on the market,” emphasizes Rick Pearson, Shop Foreman at Redpath. “There’s no other.”

Small footprint

When designing the Redbore 30, it was the compact and lightweight construction of the hydraulic motor that was the deciding factor. It occupies minimum volume since it has no gear reduction, couplings and foundations, which would require additional space. In addition the motor is very robust and not sensitive to the high shock loads “The Hägglunds drive changes the Redbore 30 from a typical requirement of mining to a profitable production machine,” Pearson emphasizes. Another contribution is made by a through shaft. During the drilling process, it is possible to cool the piloting and reaming bits with air and water. That makes sure that the compact Redbore 30 always keeps a cool head as it cuts through the rock, at variable speed and applying high torque with torque limiting.