Variable massage apparatus having a clutch selectively engaging alternate gears

A massage apparatus mountable behind the back of a chair, comprising:

• A. a flat horizontal platform;
• B. vertically extending guiding means mounted perpendicularly to said platform;
• C. motor means mounted on said platform including a shaft that is disposed in parallel to said guiding means;
• D. a massage mechanism unit slidably mounted over said guiding means and including two sets of gears and clutch means for transmitting the rotation of said shaft and for selectively engaging one of said sets of gears depending on the direction of rotation of the shaft of said motor means and said clutch means further including a clutch member of cylindrical shape and having an external thread and a cylindrical clutch housing coaxially housing said clutch member, said housing including an internal thread compatible with said external thread thereby allowing said clutch member to longitudinally travel inside said housing to engage one of said two gears connected to said shaft member;
• E. two shaft members rigidly connected to each one of said gears;
• F. linkage means having two ends and said linkage means being pivotally mounted to said two shaft members on one end and further including each of said linkage means having at least one rubber wheel rotatably mounted at the other end so that the rotation of said gears impart a predetermined reciprocating movement to the ends having said wheels mounted thereon and said wheels positioned in the area behind the back of said chair so that said unit may travel up and down the spine of a user.