Main Pump Units GeneralSee chapter 13 for the data sheet with the specifications of the pump type and documentation about the pumps on your HPU. Maintenance/RefurbishmentMost of the pump failures are attributed by fluid contamination, if the oil cleanliness is properly maintained, the chance of failure in the pumps is reduced. Pump malfunction can be recognized by loss of hydraulic power or strange pump noise. It is advised to perform a preventive refurbishment of the pump after 20.000 hrs. at 100% DC or after ten years of use. Tanktop return filter GeneralThe return filter filtrates the incoming oil to the hydraulic system. The return filter is equipped with an electrical contamination switch. MaintenanceTo change a filter take the following steps: switch off and de-pressurize the hydraulic system, unscrew the cap of the filter housing, remove filter element from element fixation (examine surface of element for dirt residue and larger particles; these can indicate damage to components of the UniteQ HPU), replace filter element, clean the cap,