How may pressure from an engine-driven hydraulic pump be regulated?

The regulation of pressure from an engine-driven hydraulic pump is most effectively accomplished using a variable-displacement pump. This type of pump is designed to adjust the volume of fluid it displaces in response to changing system demands, allowing for precise control over the hydraulic pressure output.

As the system requires different amounts of hydraulic fluid, the variable-displacement pump can change its capacity, either increasing or decreasing the flow to maintain optimal pressure levels. This adaptability is crucial in applications where load conditions may vary, ensuring that the hydraulic system operates efficiently and safely across a range of performance needs.

In contrast, constant displacement and fixed-displacement pumps do not offer this level of regulation. A constant displacement pump maintains a set flow rate regardless of the pressure or load, which can lead to inefficiencies and potential system overloads. Similarly, a fixed-displacement pump also delivers a constant flow, which can be inappropriate for varying operational requirements. The pneumatic pressure system, while a method to generate pressure, does not relate specifically to the same hydraulic principles as the pumps mentioned.