Patent ID: 8006783

Claim:
A down-the-hole assembly, comprising: a housing having a central axis; a mechanical gear box positioned within said housing, said mechanical gear box further being coupled to said housing such that rotation of said housing at a first rotational rate provides a rotary input to said mechanical gear box, wherein said mechanical gear box includes: a ring gear operatively associated with said housing, a bit gear operatively associated with said ring gear, and a grounding ring operatively associated with said bit gear; an isolation mechanism for separating rotation of said housing from said grounding ring; and a rotary cutting bit coupled to said mechanical gear box, said mechanical gear box being configured to rotate said rotary cutting bit at a second rotational rate in response to said rotary input from said housing, said second rotational rate being greater than said first rotational rate, said mechanical gear box being further configured to cause said rotary cutting bit to orbit about said central axis of said housing.