🔍 Key Concepts

• Hydraulic spool valves and how many discrete positions the spool can shift into • What the springs on both ends of the spool usually indicate about a valve’s center (neutral) position • Difference between discrete positions and a continuously variable or infinite range of positions in control valves

💭 Think About

• Count how many clearly defined working positions the spool can have between the end stops as it shifts left and right inside the body • Ask yourself whether the operator selects fixed detent positions, or can smoothly stop the spool anywhere along its travel to meter flow • Look at the port labels (T, B, P, A) and consider how many distinct flow patterns this spool can create as it moves

✅ Before You Answer

• Identify whether there is a center (neutral) position in addition to the two extreme positions • Decide if the valve’s design suggests fixed detents or a truly continuously variable metering movement • Confirm that the name you choose correctly reflects the number of positions suggested by the internal spool geometry and springs