Power transmission mechanism of power-driven rotary tools

A compact power-driven rotary tool including a spindle having a front end and a rear end and extending along a longitudinal axis, said spindle being alternately disposable between an impact mode to allow for both a rotating movement and a reciprocating movement of said spindle, and a non-impact mode to allow only a rotating movement of said spindle, said tool comprising

• a splittable housing including a front end and a rear end and being split along said longitudinal axis,
• motor means mounted substantially in said housing rear end having a rotatable output shaft with a selected rotational speed and extending therefrom along said longitudinal axis,
• force transmission means extending substantially parallel to said motor output shaft and associated therewith for receiving and transmitting said rotation of said motor output shaft, said transmission means including change gear means for changing the rotational speed of said motor output shaft,
• said spindle being rotatably mounted in said housing front end for receiving said rotation of said transmission means, and having a front end to which a tool implement is replaceably and detachably attached,
• impact means disposed on said rear end of said spindle for imparting a reciprocating movement along said longitudinal axis to said spindle, and
• clutch means, mounted on said spindle between said front and rear ends and axially spaced from said impact means along said axis, said clutch means including
• spring means having a first end and extending along said longitudinal axis,
• a rotatable first clutch member mounted on said spindle and rotatably coupled to said transmission means, said first clutch member being free of movement along said longitudinal axis, and
• a movable second clutch member movable along said longitudinal axis and mounted on said spindle, and having a first face and a second face, said first face being placed in intimate facing contact with said first clutch member by said spring means, said movable clutch member second face supporting said first end of said spring means,
• wherein said spindle includes one or more ball spline grooves formed thereon and having one or more rotatable balls received therein, respectively, said movable clutch member of said clutch means having one or more ball grooves formed thereon at a location substantially complementary to said one or more ball spline grooves, said one or more balls slidably coupling said second clutch member and said first clutch member with said spindle for allowing said second clutch member to rotate and reciprocatingly move along said longitudinal axis in response to a rotating movement and a reciprocating movement of said spindle.