Patent ID: 8616303

Claim:
A down-the-hole assembly, comprising: a down-the-hole motor; a mechanical gear box coupled to the down-the-hole motor, the mechanical gear box being adapted to receive a rotational input of a first rotational rate from the down-the-hole motor, the mechanical gear box comprising: a ring gear; a bit gear operatively associated with the ring gear; and at least one orbital gear operatively associated with the ring gear; and a rotary cutting bit coupled to the mechanical gear box, the mechanical gear box being configured to rotate the rotary cutting bit at a second rotational rate in response to the rotational input from the down-the-hole motor, the second rotational rate varying from the first rotational rate; a grounding ring operatively associated with at least one of the bit gear and an orbital gear of the at least one orbital gear; and an isolation assembly configured to separate rotation of the ring gear from the grounding ring.