Twin Disc Incorporated

Clairdel C Cox

Raymond C Schneider

A mobile rig for drilling blast holes comprises a rotatable drill holder mounted on an upright mast. A torque converter and transmission are connected between a prime mover (I.C. engine or electric motor) on the rig and the drill holder. The torque converter includes a servo controlled modulatable torque converter input (slipping) clutch for driving the drill holder at desired rotational speeds. The transmission includes a pair of solenoid actuated directional clutches selectively energized for driving the drill holder in either forward or reverse directions (threading). A control system, which includes an improved manually operable electromechanical drill control unit having mechanically interlocked separate control knobs for direction (threading) and speed control, is provided to sequence the clutches so as to enable drill holder rotation in either forward or reverse direction from neutral; to enable forward drill holder rotation at any selected speed within a predetermined speed range; to effect reverse drill holder rotation at a predetermined minimum speed; to maintain the selected or predetermined drill speed constant by automatically matching torque to load; to correctly engage the proper directional clutch before the torque converter input clutch begins to engage to thereby smooth out starting of drill holder rotation; and to permit operator manipulation of the direction and speed control knobs only in a predetermined sequence to thereby prevent damage to the drill and drill rig.

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Rockford, IL, United States of America

Clairdel C Cox