The most common spool types include open center, closed center, partially closed center, semi-open center, and tandem center. An open center valve allows fluid to flow freely through the valve when the spool is in its neutral position, whereas a closed center valve...
In addition to the means of shifting the spool, the way in which the spool returns to its neutral or starting position is another important aspect of valve design. This return mechanism is often achieved through a spring, which automatically pushes the spool back into...
