Which type of pump requires an additional pressure regulator for optimal performance?

The correct choice is the constant displacement pump, as this type of pump delivers a fixed volume of fluid with each cycle regardless of the pressure conditions in the system. When operating under varying load conditions, a constant displacement pump can lead to excessive pressure buildup, which can cause damage to the system components if not properly regulated. Therefore, an additional pressure regulator is necessary to maintain safety and functionality by allowing the system to relieve excess pressure.

In contrast, gear type pumps and piston type pumps, while they have their own operating characteristics, do not inherently require a pressure regulator for optimal performance under typical conditions. Gear type pumps often manage pressure through their design, allowing for the flow to be controlled simply by adjusting the motor speed. Piston type pumps can also effectively manage pressure in certain hydraulic applications without the need for a regulator.

Variable displacement pumps are designed to adjust the flow rate and pressure on-demand, automatically accommodating changes in system requirements. This adaptability negates the need for an additional pressure regulator since the pump itself manages pressure fluctuations effectively.

Thus, the requirement for a pressure regulator is primarily associated with constant displacement pumps, underscoring the importance of managing pressure to prevent potential system damage.