Tips For Designing Hydraulic Power Units With Increased Performance and Reliability
Hydraulic power units are engineered systems where reliability, efficiency, and service life outcomes are defined long before the machine is switched on. Flow rates, operating pressures, and power density are often treated as core design parameters. Yet contamination control and hydraulic filtration are often considered late in the design phase and constrained by the remaining space rather than the system requirements.
This late-stage approach introduces unnecessary risk across the entire lifecycle of the hydraulic power unit. When filtration is specified after the core layout is finalised, then compromises become unavoidable. Filters are selected based on available mounting space instead of contamination load. Nominal flow ratings replace duty cycle analysis. Breather filtration is treated as an accessory rather than a critical system component and monitoring provisions can be excluded altogether.
The result is a hydraulic power unit that may meet the specification on paper but operates continuously at elevated contamination levels in the field.
Hengst proudly offers a range of flexible and customisable hydraulic filtration solutions for engineers building HPU’s. With Hengst contamination control is engineered into the hydraulic power unit architecture from the outset, using application-specific filtration solutions and integrated monitoring technologies. This approach aligns filtration performance with real operating conditions, giving engineers greater confidence in long-term reliability.
The hidden cost of late-stage filtration decisions
When contamination control is compromised at the design stage, the consequences are rarely immediate. Wear debris circulates undetected, clearances degrade, and heat generation increases gradually. Once contamination reaches a critical threshold, wear progression accelerates rapidly.
These failures are often mistaken as pump or valve issues. This may mean that components are replaced, oil is changed prematurely, and maintenance intervals are shortened, while the underlying cause remains unchanged. The root cause is that contamination control was not properly engineered into the HPU.
Reservoir geometry, flow paths, service access, and operating temperature are all design variables that influence cleanliness. A well-designed hydraulic power unit should provide a controlled environment where contamination and maintenance can be easily and predictably managed.
Contamination begins before first startup
Hydraulic power unit’s often contain contamination before commissioning. Machining processes generate metal particles. Pipe cutting introduces scale and burrs. Welding leaves slag and residue. Assembly exposes components to airborne contaminants. Even with careful cleaning, residual contamination remains.
During initial startup, this contamination becomes the system’s first wear source. If filtration is poorly positioned or undersized, pumps ingest debris immediately. Larger particles cause surface damage, while finer particles embed into softer materials and recirculate repeatedly. Secondary contamination generation begins at the most vulnerable stage of component life.
Flushing reduces bulk contamination but does not address particles trapped in dead zones, reservoir corners, or upstream of components. These particles re-enter circulation during normal operation.
Hengst has a range of solutions to manage contamination at each step. Hengst suction filtration protect the pump from coarse particles without restricting cold-start flow. Reservoir filtration supports sediment control rather than debris migration. Return line filtration is sized for early wear debris with sufficient dirt holding capacity to prevent premature bypass.
Environmental contamination is a design variable
Airborne particles and moisture vary significantly depending on hydraulic power unit application and the facility conditions.
Thermal breathing is a major contamination pathway. As hydraulic fluid heats and cools, the reservoir continuously exchanges air. In facilities with airborne particulates or humidity, each breathing cycle introduces contamination that accumulates over time. Moisture ingress increases the risk of corrosion and accelerates fluid degradation.
Ineffective breather filtration can lead to environmental contamination that can overwhelm return filtration capacity. This means that clean oil leaving the reservoir becomes progressively contaminated despite regular filter changes.
Hengst offers high-quality breather filters to minimise environmental contamination risk.
Filter elements, cyclone effect housings, and complete monitoring solutions
Filter element performance is defined by more than micron rating alone. Filter media construction determines dirt holding capacity, pressure stability, and service life, whilst housing design impacts flow distribution.
Hengst PWR filter elements use an innovative multi-layer media to distribute contamination throughout the element, maintaining stable differential pressure while maximising dirt holding capacity. This combined with cyclone-effect technology can extend service intervals and lower operating costs.
Having monitoring solutions completes the design loop, because operating conditions and environments change. Hengst offers integrated differential pressure indicators, particle monitoring, and fluid condition sensors to enable condition-based maintenance rather than fixed service intervals.
Partner with Hengst Filtration when designing your HPU
Hengst Filtration offers a comprehensive range of hydraulic filter elements, suction filters, return line filters, breather filters, and integrated monitoring solutions designed specifically for hydraulic power units. With flexible mounting options, custom configurations, and application-driven design support. Hengst enables engineers to design filtration into the system for reliable contamination control.
For more information, contact the Hengst Filtration team.