1. Field of the Invention
The present invention relates to a hydraulic valve for controlling a single-acting cylinder.
2. Description of the Background Art
Numerous hydraulic control valves having a variety of uses are known in the prior art. For example, expired U.S. Pat. No. 1,747,899 to Hogg discloses a coal pusher for locomotive tenders including a reciprocating pin valve, the valve pin having a single pin groove for shifting fluid flow between three ports and including a passageway through the center of the pin feeding a fourth valve port for operation of a double-acting cylinder.
Expired U.S. Pat. No. 2,906,492 to Conrad discloses a valve including a reciprocating pin having a single pin groove for providing communication between an outlet port and either of an exhaust port or an intake port.
Other valves having grooved pins are shown in U.S. Pat. Nos. 2,496,036; 3,472,281; 4,022,425 and 4,367,763.
Heretofore, none of the known prior art hydraulic valves have provided for automatic reciprocation of a single-acting cylinder in the absence of electrical devices or like shifting means. Accordingly, there remains a need in the art for a reliable and relatively inexpensive hydraulic control valve which is capable of providing for automatic reciprocation of the cylinder rod of a single-acting cylinder.
USPTO Backgrounds
USPTO Backgrounds