Backhead and drill assembly with backhead

摘要: In representative embodiments, a backhead for drill assembly comprises an elongate member having proximal end connectible to source of pressurized fluid, side wall defining axial bore and open distal end. A portion the extending proximally from has inner surface cylinder shaped receive axially movable piston. The also check valve receiving area separate, during normal operation when is received in area, inlet distally Various improvements retaining distributor increasing flow efficiency are described.