🔍 Key Concepts

• Hydraulic relief valve symbol and how it’s drawn (spring-loaded, normally closed, opens to tank when pressure is high) • Difference between line (cross-port) relief at an individual motor and a main system pressure relief that protects the entire supply line • How the main pressure line is routed from the pump, through the manual transfer valve, down to the lower unit, and where it first has a path back to the reservoir

💭 Think About

• Follow the solid main pressure line from the pump outlet, through the manual transfer valve, toward the motors. Which labeled component is the first one that can open and send that pressure back to the reservoir or sump? • Look closely at the internal symbols for components D, E, L, and M. Which one clearly shows a spring-loaded valve that is normally closed and opens when pressure gets too high? • Ask yourself whether each option (D, E, L, M) is a directional control valve, a shutoff/isolation valve, or a pressure control/relief valve. Which type of control is normally used to protect the entire main pressure piping?

✅ Before You Answer

• Verify which component is connected directly between the main pressure line and the return/sump line – that’s where a main relief must be located. • Confirm that the symbol has a spring and an adjustable screw or setting, indicating it opens only when a set pressure is reached. • Make sure the device you pick protects the whole supply line, not just a single motor or branch circuit.