Retaining arrangement, sub adaptor and/or drill spindle

A retaining arrangement suitable for use with a drill string assembly having a sub adaptor and a drill spindle in use connected together via a screw thread arrangement, the retaining arrangement including:

• one or more retaining bodies, the or each retaining body comprising a connection region for removably connecting the or each retaining body to one of the sub adaptor and the drill spindle;
• and
• a first retaining or catch region adapted to catch the other of the sub adaptor and drill spindle;
• wherein the first retaining region includes a catch element;
• wherein the catch element is a peripheral flange or rib;
• wherein the connection region is removably connected to one of the sub adaptor and the drill spindle by one or more fasteners and includes one or more openings adapted to receive the one or more fasteners;
• and
• wherein the fasteners are screw thread fasteners and are removably connected to the sub adaptor or drill spindle by a corresponding screw thread arrangement located on the one of the sub adaptor and drill spindle.