Abstract: A valve driving apparatus comprising a case proper provided in the interior thereof with a movement conversion-transmission mechanism, a cylinder mechanism freely detachably fixed to one end of the case proper and a piston rod supporting mechanism freely detachably fixed to the other end of the case proper so as to be applicable to any kind of valve merely by the replacement of the mechanisms between which the case proper intervenes.

Abstract: A valve driving apparatus is provided with cylindrical bearing members made of a synthetic resin or a copper alloy and used for a piston rod and for a drive shaft, a lining member made of a synthetic resin for coating the inner wall of an apparatus and a resilient member made of a synthetic rubber or a synthetic resin and inserted in a groove of a piston so as to protect the valve driving apparatus from the disadvantages of wear, frictional resistance and energy loss which are produced by a reciprocating movement of the piston and the piston rod. Also a valve driving apparatus utilizing a scotch yoke type movement conversion-transmission mechanism is provided with cylindrical bearing members made of a synthetic resin or a copper alloy and attached to pins installed on a piston rod so as to prevent the aforementioned disadvantages from occurring between the pins and the scotch yokes.