Stroke-adjusting drive mechanism for machines

Apparatus for adjusting the stroke of a reciprocating member in a hydraulic drive mechanism comprising a cylinder, a piston movable in said cylinder, said piston defining a first chamber in said cylinder and having a piston rod extending outwardly from said cylinder, a conduit connected to hydraulically communicate said first chamber with hydraulic pump means for supplying pressurized fluid to said first chamber to move said piston through a stroke in said cylinder, restricting valve means arranged between said first chamber and said conduit for restricting flow therebetween, stroke adjusting means arranged to be adjustably positioned relative to said piston rod for urging said restricting valve means into flow restricting relation between said first chamber and said conduit at a predetermined position along said stroke,

• said piston rod being formed with a cylindrical chamber having a threaded inner wall, said stroke adjusting means including a shaft member rotatably arranged in said cylindrical chamber and a rotatable adjusting member threadably engaged with said threaded inner wall, said shaft member extending slidably through said adjusting member, said restricting valve means being located at the end of said shaft member, and said adjusting member contacting said restricting valve means to urge the same into said flow restricting relation when said shaft member and said adjusting member are rotated to axially move said adjusting member in said cylindrical chamber and said piston is subsequently moved through its stroke in said cylinder.