Cylinder 1 contains a piston consisting of leather cup 2 clamped between disks 3 and 4. The disks are secured to piston rod 5 at whose lower end clevis 9 is secured. The clevis has axle 8 on which roller 7 rotates. Screwed into the lower cover of cylinder 1 is eye 6 to which a cable is secured. The cable runs over roller 7 to the valve being controlled. When the pressure of the working fluid in the cylinder is changed, the piston is moved together with the clevis and roller 7.
$3749$SHP,Dr$