Drill string apparatus

An indexed-rotation apparatus attached to a hydraulic breaker, jack hammer, or other reciprocating tool the indexed-rotation apparatus comprising:

• a physical coupling between a control body and a reciprocating drive end;
• a first unidirectional bearing attached to a control body, wherein the first unidirectional bearing is coupled to the reciprocating drive end;
• and
• a second unidirectional bearing attached to a housing of the apparatus,
• wherein:
• the indexed-rotation apparatus is configured such that when the drive end reciprocates, the first unidirectional bearing turns in a free-wheel direction and the second unidirectional bearing turns in an engaged direction.

A method for operating an indexing down-the-hole hammer (IDTH) comprising:

• activating the IDTH hammer to propel a drive body forward;
• causing a first helical spline to travel along a second helical spline in a direction of free rotation of a first unidirectional bearing that is coupled to the first helical spline, wherein the first unidirectional bearing is attached to a hammer drive of the drive body;
• causing a weight on a drill bit to force the hammer drive of the drive body to retract;
• and
• during a retract motion, causing the first helical spline to travel along the second helical spline in a direction of engaged rotation of the first unidirectional bearing, the engaged first unidirectional bearing causing an indexed rotational displacement of the drill bit, the displacement maintained by the second unidirectional bearing.