Hydraulic filters
The hydraulic filter maintains oil cleanliness in the power-hydraulic system — the primary drive system of excavators, loaders, cranes and forklifts. Contaminants in hydraulic oil — metal particles, seal degradation products and water — accelerate wear on pumps, motors and proportional valves. Oil cleanliness class per ISO 4406 directly affects the service life of the entire system.
We supply pressure-line filters (mounted after the pump), return-line filters (on the return to tank) and suction filters (before the pump). At Filtry.org you will find elements from HIFI Filter, SF Filter and PZL Sedziszow with filtration ratings from 3 to 25 um, compatible with Bosch Rexroth, Parker, Danfoss and Eaton systems.
Frequently asked questions
What is the difference between a pressure-line and a return-line filter?
The pressure-line filter operates downstream of the pump at 200-400 bar and protects proportional valves and hydraulic motors. The return-line filter cleans oil flowing back to the reservoir at low pressure. Both are necessary in a properly designed circuit — the pressure filter protects actuators, the return filter maintains overall circuit cleanliness.
How often should hydraulic filters be changed?
Every 500-1,000 engine hours or as indicated by the differential-pressure sensor (clogging indicator). Also replace filters after every hydraulic failure, oil change or pump repair — contaminants from damaged components circulate in the system until captured.
Can I fit a filter with a finer rating than specified?
Yes, but ensure the filter has sufficient flow capacity to avoid excessive pressure drop. An overly restrictive filter with inadequate capacity may force the bypass valve open, allowing unfiltered oil to pass.
What does ISO 4406 oil cleanliness class mean?
ISO 4406 specifies the number of particles larger than 4, 6 and 14 um per millilitre of oil. A typical servo-hydraulic system requires class 16/14/11 or better. Lower numbers mean cleaner oil and longer component life.