Surgical air drill

Claim 1

A rotary surgical instrument comprising: a main housing having an air motor mounted therewithin; means for supplying air under pressure to said motor to cause controlled rotation thereof; a forwardly extending shaft coupled to said air motor for rotation therewith; a hand piece removably coupled to said main housing, said hand piece comprising; a housing; a shaft rotatably mounted within said hand piece housing; and a cutting tool having a shaft secured to the forward end of said hand piece shaft for rotation therewith; and means for removably coupling said hand piece shaft to said air motor shaft for rotation together of said shafts; said coupling means comprising a sleeve secured to the forward end of said air motor shaft for receiving the rearward end of said hand piece shaft, the forward end of said air motor shaft and the rearward end of said hand piece shaft having similarly splined external surfaces, the internal surface of said sleeve having mating splines; the forward end of said sleeve being formed with lands at the ends of the inwardly projecting ridges of said splined surface and depressions between said lands at the ends of the grooves between said ridges; the rearward end of said hand piece shaft being formed with radial ridges at the ends of the outwardly projecting splines and depressions between said ridges at the ends of the grooves between said splines.