Question 190General Subjects - Assistant Engineer

70% to pass

Which of the statements is true concerning the illustrated hydraulic circuit when the directional control valve is centered? Illustration GS-0105

Diagram for USCG General Subjects Assistant: Which of the statements is true concerning the illustrated hydraulic circuit...

AOil pressure to both sides of the actuator will be equal as the pump discharge flow is directed across the relief valve.

BA pressure differential will exist between the two ends of the actuator, with pump discharge lower than normal due to flow across the unloading valve.

CThe oil pressure will equalize at both ends of the actuator and the pump will discharge through the reducing valve to the sump.

DThe load on the actuator may cause a difference in pressure to exist between the rod and cap end, and oil discharging to the sump across the relief valve with the pump operating.

AI Explanation

The correct answer is D. When the directional control valve is centered, the oil pressure will equalize at both ends of the actuator, but a difference in pressure may exist between the rod and cap end due to the load on the actuator. The pump will continue to discharge oil, with the excess flow being directed across the relief valve to the sump. The other options are incorrect because: A) The pressure will not be equal on both sides of the actuator when the load is unbalanced. B) The pressure differential will not be across the unloading valve, but rather the actuator itself. C) The reducing valve will not be involved in this scenario, as the pump will continue to operate and discharge to the relief valve.