🔍 Key Concepts
• Trace the hydraulic lines from the boom cylinder (item 15) back down to the manifold to see whether it connects to valve 8, 9, or 10 and to port A or B on that valve.
• For a double‑acting cylinder, decide which side of the cylinder must be pressurized to raise (extend) the boom and which side must be connected to return.
• Look carefully at the spool symbol for each position (Pos.1 / Pos.3) on the selected valve and see in which position pump flow is directed to the correct port (A or B) to raise the boom.
💭 Think About
• Which bottom directional valve (8, 9, or 10) is actually feeding the boom cylinder shown at the top center of the drawing? Follow only the solid hydraulic lines, not the dashed pilot lines.
• Once you’ve identified that valve, when the boom is raised in real life, does the cylinder rod extend or retract? Which side of the cylinder symbol corresponds to that motion?
• Compare Pos.1 and Pos.3 of that valve. In which position does the pump line connect to the side of the cylinder you decided must be pressurized to raise the boom, while the opposite side is open to tank/return?
✅ Before You Answer
• Verify you have correctly identified the boom cylinder (15) and its two ports, and which port corresponds to boom‑up motion.
• Verify the hydraulic line from that boom‑up port goes to either port A or port B of only one of the lower valves (8, 9, or 10).
• Verify that the spool position you choose actually sends pump flow to the boom‑up port and simultaneously routes the opposite port to tank/return, not to pressure.