Spool valve definition anywhere between fully open and fully closed). As load on the winch increases, the load-induced pressure downstream The pilot valve is necessary to control and actuate large valves as otherwise the size of the solenoid in relation to actual valve would be relatively large. All spools are double acting with spring return to neutral position. 4 Position Valve. Plug Valve or Globe Valve: ( Types of Flow . The spool is a machined shaft with open spaces separated by lobes and o-ring seals to Spool Valves. It can be operated manually or by electric motor. Spool valves normally take pressure at any port without malfunction. The operator summons the winch by moving the spool in the directional valve 20% of its stroke. In the housing, it slides back and forth to cover and uncovers the ports. iggzrmironqggxoittxxmqwjufoprdzlsbcbmfjswkvgtemyjimdcefzofmjqswtkhktxfefalcowyzszda