Clamp

In an apparatus for driving an elongated drill steel a drill steel clamping means comprising:

• support means carried by such an apparatus;
• jaw means carried by said support means and engageable in clamping engagement with such drill steel;
• said jaw means comprising at least a pair of relatively movable jaw members with at least one of said jaw members having a formed clamping surface portion engageable with an axially extending formed peripheral portion of such a drill steel;
• said formed clamping surface portion being comprised of axially spaced alternate land and groove portions and intervening inclined flank portions located axially intermediate said land and groove portions;
• and said clamping surface portion being engageable with such drill steel in clamping engagement constituted solely of engagement between said inclined flank portions and such formed peripheral portion.