Down-the-hole Drill Reverse Exhaust System

[0018]Certain terminology is used in the following description for convenience only and is not limiting. The words “right,”“left,”“upper,” and “lower” designate directions in the drawings to which reference is made. For purposes of convenience, “distal” is generally referred to as toward the drill bit end of the DHD hammer, and “proximal” is generally referred to as toward the backhead end of the DHD hammer as illustrated in FIG. 1. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.

[0019]In a preferred embodiment, the present invention provides for a DHD hammer 5 having a percussive actuator assembly 10 as shown in FIGS. 1 and 2, for use with a conventional down-the-hole drill pipe (not shown). Referring to FIG. 1, the DHD hammer 5 includes an actuator assembly 10, a casing 12, such as an elongated housing 12, and a drill bit 16. The actuator assembly 10 includes a piston 14, a backhead 18, a cylinder 54, and a cylinder ca