Importance

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Abstract

A device reducing the deleterious torque in a shock absorbing, rotary drive coupling unit used with a rotary mine drilling machine comprising: a drive plate connectable to a drive shaft of the rotary drilling machine, a driven plate connectable to a driven shaft which has a drill bit, a center portion for coupling the drive plate to the driven plate wherein the center portion includes a deformable shock, vibration and torque-absorbing member, and torque-relief means comprised of a first engagement member(s) connectable to the drive plate and a second engagement member(s) connectable to the driven plate. When the drill bit snags or jams during the operation of the rotary drilling machine, the torque-absorbing member deforms and absorbs some of the torque generated therefrom. When the torque generated from a snag or jam reaches a predetermined level, the engagement members of the drive plate physically contact the engagement member(s) of the driven plate causing the drive plate to directly drive the driven plate thus preventing any additional torque from being applied to the torque-absorbing member. An optional tensile-force relief member is provided which is mounted to the driven plate and is positioned above the drive plate. The drive plate physically contacts the tensile-force relief member in response to a predetermined amount of lifting force applied to the drive plate thereby limiting the distance the torque-absorbing member stretches when the torque control device is lifted from a blast hole.

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First Claim