🔍 Key Concepts

• Hydraulic motor load holding – how a hoist drum is kept from turning when fluid flow stops • Difference between an operator‑controlled directional valve and an automatic braking or counterbalance valve • What components 4, 5, and line K actually do in the hoist (up/down) part of the circuit

💭 Think About

• On the right side of the diagram, trace the flow when the hoist control is in neutral: which component is still actively preventing the motor (and drum) from turning? • Ask yourself whether a safe crane design should depend on the operator holding a valve slightly off‑center, or on an automatic device that works even if the control is released. • Compare the function of the item in the dashed box at label 5 with any similar items at labels 14 and 18 – what common purpose do they serve?

✅ Before You Answer

• Verify which symbol at 5 represents a braking / counterbalance / load‑holding valve and whether it is placed in line K going to the hoist motor. • Confirm that component 4 is a standard directional control valve that only controls flow direction and does not, by itself, mechanically lock the drum. • Before choosing, eliminate any option that requires a manual valve position or does not match a clearly drawn braking or load‑holding device in the hoist circuit.