u201c washer u201d like elements 602 and concave washer elements 604 each of washer elements 602 604 is provided with a cylindrical aperture 606 therein to drilling mud pressure may be supplied to upper surface 714 of detent member 502 washer elements 602 604 may be of the type provided by gardner spring co of tulsa okla part no mb0500 025 s washer elements 602 604 when biased into compression by threaded set screw 604 serve to bias detent member 502 in mating engagement with apertures 340 in outer mule shoe 120 importantly in this embodiment set screw 605 having external threads 607 has an aperture 610 therein which may be hexagonal in shape to allow insertion of an allen key to allow tightening of such set screw 605 within orifice 514 in outer mule shoe 120 aperture 610 allows drilling mud pressure to be exerted on upper surface 714 of detent member 502 thereby along with washer elements 602 604 biasing such detent member 502 downwardly and into aperture 340 when such apertures 340 become aligned with orifice 514 upon landing of the arcuate camming surfaces 140 180 detent member 502 may possess a hemispherical end portion 506 or simply.