Valve driving apparatus

A valve driving apparatus comprising:

• a casing having a first bearing portion receiving aperture at a first end thereof and a second bearing portion receiving aperture at a second end thereof and aligned with said first bearing portion receiving aperture along an axis;
• a valve driving shaft extending through said casing transverse to and offset from said axis;
• a movement conversion-transmission mechanism connected to said valve driving shaft;
• a plurality of rods interchangably positionable in said casing along said axis and through said apertures and being connectable to said movement conversion-transmission mechanism, and each having a first end projecting through said first bearing portion receiving aperture and a second end projecting through said second bearing portion receiving aperture, each piston rod having a piston attaching means at the first end thereof and one piston rod having the second end free of any attaching means and a second piston rod having the second end with plate attaching means thereon;
• a plurality of different size piston-cylinder mechanisms interchangably attachable to said first end of said casing, each piston-cylinder mechanism having (1) a cylinder with ports for the inlet and outlet of pressure fluid, (2) a piston slidable in said cylinder and attachable by the piston attaching means to the first end of a piston rod, and (3) a first bearing portion on the end of the cylinder which is toward said casing, said first bearing portion having a bearing aperture therethrough through which a piston rod extends when said piston-cylinder mechanism is attached to said casing and supporting the piston rod, and said first bearing portion further having a circumferential portion fitting into said first aperture in said casing, and each piston cylinder mechanism having a means for attaching it to said first end of said casing;
• and
• a plurality of piston rod movement control means interchangably attachable to said second end of said casing, each having (1) a housing with a bearing portion constituting an end plate with a projection thereon of a size for being matingly receiving in said second bearing portion receiving aperture in said casing, said bearing portion having a bearing aperture therethrough through which a piston rod extends when said piston rod movement control means is attached to said casing and supporting the piston rod, and (2) means for attaching said piston rod movement control means to said second end of said casing, one of said piston rod movement control means having a stop at the end thereof remote from the end plate thereof and the interior of said housing receiving only the piston rod and being traversed thereby and the housing being attached to said second end of said casing when the one piston rod is positioned in said casing, and a second of said piston rod movement control means having a stop at the end thereof remote from the end plate and a spring holder slidable in said housing and being attached to the second end of said second piston rod when said second piston rod is positioned in said casing and also having a spring in said housing between said spring holder and the end of the housing at which said stop is positioned.