Patent ID: 7624822

Claim:
Apparatus for transmitting percussive forces comprising: a male member threadedly mounted in a female member by a thread joint, the thread joint comprising a male thread on the male member and a female thread on the female member, the thread joint defining a longitudinal axis; the male member including a first portion including an outer surface having a maximum first outer cross section, a second portion having a second maximum outer cross section, and a third portion having the male thread formed thereon, the second portion disposed axially between the first and third portions, the male thread including a thread start and a thread end; the third portion terminating in an axially facing first end surface; the female member comprising a recess in which the female thread is formed, the female thread having a mouth defined by a ring-shaped second end surface, the recess including a stop face abutted by the first end surface, the recess including a cylindrical inner surface disposed between the second end surface and the female thread, the inner surface facing the male member, wherein the inner surface has a diameter at least as large as the second maximum outer cross section, and smaller than the first maximum outer cross section; wherein the thread end of the male thread is situated within the recess; wherein a first imaginary cylinder constituting an axial extension of the inner surface intersects the first portion of the male member, and a second imaginary cylinder constituting an axial extension of an outermost surface of the female member extends outside of the first portion of the male member; the male and female members forming a conduit for transporting a flushing medium.