ASA Hydraulic And Pneumatic Power System Practice Test

When fluid is diverted to the reservoir from a constant-displacement hydraulic pump, the principle of constant displacement comes into play. A constant-displacement pump delivers a fixed volume of fluid with each rotation of the pump's mechanism. As fluid is diverted to the reservoir, the pressure within the hydraulic system may drop because the return line often has lower resistance, allowing fluid to move there more easily. However, the total output volume from the pump remains the same, assuming the pump continues to operate. This is because the pump is still producing a constant volume of fluid, irrespective of where that fluid is directed; some of it simply flows back to the reservoir rather than being used in the system. Hence, while the output pressure can decrease due to the reduction in system resistance, the output volume stays consistent with the pump's design. This understanding clarifies why the output pressure reduces while the volume remains unchanged when fluid is diverted to the reservoir.