A hydraulic power unit needs to do more than deliver pressure and flow. It needs to work with the machine, fit the environment, meet performance requirements, and hold up to the demands of daily operation.
Whether you’re designing a new industrial hydraulic system, replacing an aging HPU, or upgrading equipment that’s no longer performing as it should, the decisions made during specification can have a significant impact on reliability, efficiency, maintenance, and long-term operating costs.
And while horsepower, pressure, and flow are important starting points, they’re only part of the equation.
Before specifying your next industrial hydraulic power unit, here are 15 factors worth working through.
In addition, Progressive Power has developed a helpful download here to help.
Start With the Application, Not the Components
One of the most common challenges in hydraulic power unit design is focusing on individual components before fully understanding how the system will operate.
A pump, motor, reservoir, and control valves might meet the basic specifications on paper. But will the system perform through repeated cycles? Can it handle continuous operation? Is there enough room for maintenance? What happens when operating temperatures rise?
The answers influence everything from component selection to the overall HPU layout.
That’s why a good specification starts with understanding the machine, its operating conditions, and what the hydraulic system actually needs to accomplish.
1. Safety Requirements and System Protection
Safety should be part of the hydraulic power unit design from the beginning, not something addressed after components have been selected.
Industrial hydraulic systems operate under pressure, often in demanding environments where leaks, excessive heat, unexpected movement, or component failures can create serious hazards.
Consider the application’s operating pressures, potential failure points, pressure relief requirements, and applicable safety standards.
The question to ask: What needs to happen to keep the equipment and operators protected during normal operation, maintenance, and potential system failures?
2. Actuator Functions and Control Requirements
What does the hydraulic system need to move, lift, clamp, rotate, or position?
Understanding the function of each actuator is essential when specifying hydraulic control valves, especially when those valves are mounted directly on the power unit.
Actuator requirements influence pressure, flow, valve selection, and the system’s control logic.
A system with multiple actuators may also require consideration of simultaneous operation, sequencing, and different operating demands.
3. Machine Duty Cycle
Not every hydraulic power unit operates under the same conditions.
Some systems run continuously throughout a production shift. Others operate intermittently, cycling on and off throughout the day.
The machine’s duty cycle affects motor selection, heat generation, reservoir requirements, cooling, and component life.
A hydraulic power unit designed for occasional operation may not be appropriate for continuous-duty applications.
Understanding how often and how long the equipment operates helps ensure the HPU is designed for its actual workload.
4. Required Actuator Cycle Times
How quickly does each actuator need to complete its movement?
Cycle time is directly related to hydraulic flow requirements and can influence pump sizing, valve selection, and overall system performance.
A system that delivers sufficient pressure but inadequate flow may still operate too slowly to meet production requirements.
When specifying an HPU, consider the required speed of each actuator, operating loads, and whether multiple functions must operate at the same time.
5. New Equipment or an Existing HPU Replacement?
There’s a significant difference between designing a hydraulic power unit for a new machine and replacing one that’s already in service.
With new equipment, there may be greater flexibility in layout, controls, and component selection.
Replacing an existing HPU introduces additional considerations:
- Compatibility with existing hydraulic components
- Current pressure and flow requirements
- Available installation space
- Electrical and control system connections
- Changes in operating demands since the original installation
- Availability of replacement parts for older equipment
An HPU replacement doesn’t always need to duplicate the original design.
In some cases, a hydraulic retrofit or custom power unit can address the original system’s limitations while maintaining compatibility with the equipment.
6. Noise Requirements
Hydraulic power units can generate significant operating noise, particularly in manufacturing environments where equipment runs for extended periods.
Noise requirements may influence pump selection, motor configuration, mounting, enclosure design, and overall HPU layout.
For facilities with acoustic restrictions or operator workstations near the equipment, noise should be considered early in the specification process.
7. Space and Installation Limitations
An HPU might meet every performance requirement and still be difficult to install or maintain if the physical layout hasn’t been considered.
Before finalizing the design, evaluate:
- Available floor space and equipment clearances
- Height and width restrictions
- Access for routine maintenance
- Hose and piping connections
- Component accessibility
- Ventilation and cooling space
Compact hydraulic power units and custom layouts can help address limited installation space, but accessibility shouldn’t be sacrificed simply to reduce the footprint.
8. Hydraulic Fluid Selection
The hydraulic fluid affects more than lubrication.
Fluid type and viscosity influence pump performance, component compatibility, operating temperature, and overall system reliability.
Consider the fluid’s viscosity across the expected temperature range, compatibility with seals and other components, and any environmental or application-specific requirements.
Selecting the right hydraulic fluid is an important part of protecting the system and maintaining consistent operation.
9. Electric Motor and Control Power Specifications
Motor selection needs to account for the hydraulic system’s power requirements and the electrical infrastructure available at the facility.
Important specifications include:
- Motor horsepower
- Voltage and phase
- Operating duty
- Starting and control requirements
- Control power for valves, sensors, and instrumentation
Electrical and hydraulic requirements need to work together. Confirming both early can help avoid installation challenges and unnecessary modifications later.
10. Pressure, Temperature, and Filter Condition Indicators
How will operators and maintenance teams know when something isn’t operating as expected?
Visual and electrical indicators can provide important information about system conditions, including:
- Excessive hydraulic pressure
- High operating temperatures
- Dirty or restricted filters
Depending on the application, these may include gauges, warning indicators, electrical switches, or signals integrated with the machine’s control system.
The goal is to make potential problems easier to identify before they lead to more serious equipment issues or unplanned downtime.
11. Expected Operational Life
How long is the hydraulic power unit expected to remain in service?
A system intended for years of continuous industrial operation may require different component choices than one designed for occasional or short-term use.
Consider expected operating hours, maintenance requirements, component availability, and the anticipated life of the equipment.
Long-term serviceability matters, particularly when specifying hydraulic systems for machinery that may remain in operation for decades.
12. Filtration and Component Specifications
Contamination is a major concern in hydraulic system performance and component life.
Filtration requirements should be based on the needs of the system and the cleanliness requirements of its components.
Consider filter ratings, component tolerances, filter placement, and maintenance accessibility.
Proper filtration helps protect pumps, valves, and other hydraulic components from contamination-related wear and performance problems.
13. Hydraulic Cooling Requirements
Heat is a natural byproduct of hydraulic system operation, but excessive temperatures can affect fluid properties, component performance, and reliability.
Cooling requirements depend on factors such as duty cycle, system efficiency, operating environment, and heat generation.
Some applications may be adequately cooled through the reservoir and surrounding environment. Others may require heat exchangers or additional cooling equipment.
Cooling should be evaluated based on the system’s expected operating conditions, not simply added after overheating becomes a problem.
14. Standard or Custom Reservoir Layout
The reservoir plays an important role in hydraulic fluid storage, cooling, and overall system operation.
A standard reservoir configuration may be appropriate for many applications, while others benefit from a custom layout to accommodate space limitations, component placement, or maintenance access.
Reservoir selection should account for fluid capacity, system operating requirements, available space, and serviceability.
The right layout can make the HPU easier to integrate into the machine and easier to maintain over its operating life.
15. Operator, Maintenance, and Customer Preferences
Technical specifications are essential, but the people who operate and maintain the equipment often have valuable insight into what works and what doesn’t.
Consider their preferences for component accessibility, controls, indicators, maintenance procedures, and overall layout.
A hydraulic power unit that meets the engineering requirements but creates unnecessary challenges for the maintenance team may not be the best long-term solution.
Sometimes, the most useful design feedback comes from the people who work with the equipment every day.
Bringing It All Together: Why HPU Design Is More Than a Parts List
These 15 considerations are interconnected.
Duty cycle affects heat generation. Cycle times influence flow requirements. Space limitations can change reservoir and component layouts. Filtration, fluid selection, and cooling all contribute to long-term reliability.
A change in one specification can influence several others.
That’s why specifying an industrial hydraulic power unit isn’t simply a matter of choosing a pump, motor, and reservoir.
It requires understanding the application as a complete hydraulic system.
And when you’re working with aging equipment, unusual operating requirements, limited space, or hard-to-find components, the right solution may not be something available off the shelf.
Custom Hydraulic Power Units: Experience Makes the Difference
At Progressive Power & Control, we’ve spent decades helping customers work through hydraulic challenges that don’t always have straightforward answers.
From new OEM hydraulic systems and custom hydraulic power units to industrial hydraulic retrofits, component selection, and MRO support, our team understands how the individual components need to work together.
Our Indianapolis-based team works with engineers, equipment manufacturers, maintenance professionals, and plant operators to evaluate system requirements and develop practical hydraulic solutions.
Whether you’re starting with a detailed specification or trying to replace an HPU that’s been running for decades, you don’t need to have every answer before reaching out.
Bring us the application. Bring us the specifications. Bring us the challenge.
We’ll help you work through the options.
Progressive Power & Control
317-849-5115
info@progressivepower.net
We know hydraulics.
