TWO STAGE SPOOL CENTERING MECHANISM

摘要

A valve arrangement includes a spool movable in first and second strokes. A first biasing member has a first spring constant and a first preload, and a second biasing member has a second spring constant lower than the first spring constant and a second preload higher than the first preload. The first biasing member and not the second biasing member biases t he spool toward the center position through the entire first stroke and during movement of t he spool from a center position to an intermediate position within the second stroke. The first and second biasing members act in series to bias the spool toward the center position during movement of the spool from the intermediate position to an end of the second stroke.