If a hydraulic system has constant pump flow and you increase resistance to flow, what happens to system pressure?

If a hydraulic system has constant pump flow and you increase resistance to flow, what happens to system pressure?

• A. Pressure increases
• B. Pressure decreases
• C. Pressure remains the same
• D. Pressure fluctuates randomly

Answer: (A)

With a pump that holds the flow steady, the pressure in the circuit adjusts to push that fixed amount of fluid through whatever resistance exists. The pressure drop across a resistance is proportional to the flow times the resistance. So, if you increase the resistance while keeping the flow the same, the pump must generate a higher pressure to overcome that resistance. In short, higher resistance with constant flow causes the system pressure to rise. (If a relief valve or safety limit is present, pressure may stop increasing once that limit is reached, but the immediate effect of more resistance is an increase in pressure.)

With a pump that holds the flow steady, the pressure in the circuit adjusts to push that fixed amount of fluid through whatever resistance exists. The pressure drop across a resistance is proportional to the flow times the resistance. So, if you increase the resistance while keeping the flow the same, the pump must generate a higher pressure to overcome that resistance. In short, higher resistance with constant flow causes the system pressure to rise. (If a relief valve or safety limit is present, pressure may stop increasing once that limit is reached, but the immediate effect of more resistance is an increase in pressure.)