PILOT PRESSURE SUB-ASSEMBLY FOR FLUID CONTROL VALVE

A fluid control valve includes a spring biased pilot pressure sub-assembly for adjustably setting an initial step pressure. The sub-assembly includes a spring seat and an axially movable spool. The spool includes a body portion having a threaded outer surface. A pair of lock nuts are threaded on the threaded body portion. A pilot spring reacts between the lock nuts and the spring seat. The magnitude of the initial step pressure is dependent upon the magnitude of the force exerted by this pilot spring. The magnitude of this force can be adjusted by changing the position of the lock nuts relative to the spring seat. Because they are threaded onto the spool, rotation of the lock nuts causes axial movement relative thereto. Thus, the position of the lock nuts on the spool can be adjusted simply by rotating them relative to the spool. Such axial movement can be performed to increase or decrease (depending upon the direction of rotation) the effective length of the pilot spring and, therefore, the spring force generated thereby. As a result, the magnitude of the initial step pressure increase can be adjusted quickly and easily.