How to Match & Select a Hydraulic Power Unit: Complete Guide for Industrial & Machinery Applications

A hydraulic power unit (HPU) is the heart of any hydraulic system. It supplies pressurized fluid to drive cylinders, motors, valves and other actuators. However, choosing the wrong hydraulic power unit leads to slow operation, overheating, high energy consumption, component damage and frequent breakdowns.

Matching a hydraulic power unit correctly requires calculating pressure, flow, power, tank volume and matching all parts to your actual working conditions. In this guide, we explain how to professionally match a hydraulic power unit for construction machinery, industrial equipment, lifting systems, presses and custom hydraulic systems.

1. Confirm System Working Pressure

Pressure is the most basic parameter for hydraulic power unit matching. It directly determines the pump, valve, cylinder and pipe selection.

• Check the maximum working pressure of your hydraulic cylinder or motor

• Reserve a safety margin (usually 1.25 × actual working pressure)

• Common pressure levels:

• Low pressure: ≤7 MPa

• Medium pressure: 7–21 MPa

• High pressure: 21–35 MPa

If pressure is insufficient, the load cannot be lifted or moved. If pressure is too high, it wastes energy and shortens seal life.

2. Calculate Required Flow Rate

Flow rate determines the moving speed of your hydraulic cylinder or motor.

To calculate required flow:

• Flow (L/min) = Cylinder area × Speed × 60

• Consider simultaneous actions of multiple actuators

• Add 10%–15% margin for pipeline loss and leakage

Matching flow correctly ensures fast, stable and energy-efficient operation.

3. Match Motor Power to Hydraulic Pump

Motor power is calculated based on pressure and flow.

Formula:Power (kW) = Pressure (bar) × Flow (L/min) ÷ 600 ÷ Efficiency

Under-sizing the motor causes overheating and tripping.Over-sizing wastes electricity and increases cost.

4. Choose the Right Hydraulic Pump Type

Different pumps suit different systems:

• Gear pump: low cost, high reliability, general industrial use

• Vane pump: low noise, stable flow, precision machinery

• Piston pump: high pressure, high efficiency, heavy-duty machinery

Match pump displacement and speed to your required flow.

5. Size the Hydraulic Oil Tank Properly

Tank size affects heat dissipation, oil cleanliness and stability.

General rules:

• Tank volume = (3–5) × system flow rate

• Larger tanks for heavy-duty, long-running systems

• Add baffles, filters and air breathers for better performance

An undersized tank leads to overheating, oxidation and rapid oil deterioration.

6. Match Valves, Filters & Cooling System

A complete hydraulic power unit requires proper matching of auxiliary components:

• Control valves: match flow, pressure and control method

• Filters: ensure oil cleanliness to protect pumps and valves

• Cooler: necessary for high-load or continuous working systems

• Seals & hoses: compatible with pressure and temperature

Mismatched components are the main cause of leakage and failure.

7. Consider Working Environment & Special Conditions

Environment greatly affects hydraulic power unit matching:

• High temperature → heat-resistant oil and coolers

• Low temperature → low-temperature hydraulic oil

• Outdoor & dusty conditions → fully enclosed structure

• Explosion-proof areas → explosion-proof motor and solenoids

8. Match HPU to Actuators (Cylinders & Motors)

Final matching must be based on your actual actuators:

• Cylinder bore, stroke, speed and load

• Motor displacement and rotating speed

• Number of actuators working at the same time

• Cycle time and intermittent or continuous operation

Only in this way can the hydraulic power unit achieve ideal performance.

Conclusion

Matching a hydraulic power unit is not about choosing the biggest or most expensive one—it is about accurate calculation and reasonable matching. Correctly sized HPU ensures high efficiency, low failure rate, long service life and lower operating costs.