Pilot-actuated spool valve having rod retainer

The valve 200 includes a distal (lower) seal 260, an outer body or cage 250, a proximal (upper) seal 230, an inner sleeve or spool 240, a piston housing 201, and a piston 220. The valve 200 is actuated by the piston 220, which is responsive to a hydraulic pressure supplied via a pilot pressure port 204. At least one biasing element is used inside the piston housing 201 to bias against the pilot pressure. In particular, an outer spring 210 and a concentric inner spring 212 act against an end plate 214 and bias the piston 220 to the position shown when the pilot hydraulic pressure decreases to a certain level. The valve 200 is a normally-closed valve - i.e., in the absence of hydraulic pressure at the port 204, the valve , acting under the influence of the springs 210 and 212, closes the supply port (54) from communicating with the function port (58) and opens the function port (58) to the vent port (54). Cap nut 270 may be tightened securely to the piston rod 222 making it less likely to loosen over time.