Danfoss Series 90 Technical Information

Also see for Series 90: Installation Service manual

Contents

Danfoss Series 90 Technical Information Manual pdf 15 page image

Charge pressure filtrationTo pump caseCharge pumpHydraulic fluid reservoirFilterTo lowpressureside andcontrolScreenAdjustablecharge pressurerelief valveP102 004EW WarningRemote filter heads without bypass and poor plumbing design can encounter excessive pressure dropsthat can lead to charge pump damage in addition to contaminants being forced through the filter mediaand into the transmission loop.Fluid SelectionRatings and performance data are based on operating with hydraulic fluids containing oxidation, rustand foam inhibitors. These fluids must possess good thermal and hydrolytic stability to prevent wear,erosion, and corrosion of pump components.Never mix hydraulic fluids of different types.ReservoirThe hydrostatic system reservoir should accommodate maximum volume changes during all systemoperating modes and promote de-aeration of the fluid as it passes through the tank. A suggestedminimum total reservoir volume is 5⁄8 of the maximum charge pump flow per minute with a minimumfluid volume equal to ½ of the maximum charge pump flow per minute. This allows 30 seconds fluiddwell for removing entrained air at the maximum return flow. This is usually adequate to allow for aclosed reservoir (no breather) in most applications.Locate the reservoir outlet (charge pump inlet) above the bottom of the reservoir to take advantage ofgravity separation and prevent large foreign particles from entering the charge inlet line. A 100-125 μmscreen over the outlet port is recommended. Position the reservoir inlet (fluid return) to discharge belowthe normal fluid level, toward the interior of the tank. A baffle (or baffles) will further promote de-aerationand reduce surging of the fluid.Case DrainAll single S90 pumps are equipped with multiple drain ports. Port selection and case drain routing mustenable the pump housing to maintain a volume of oil not less than half full and normal operating casepressure limits of the unit are maintained. Case drain routing and design must consider unit case pressureratings.A case drain line must be connected to one of the case outlets to return internal leakage to the systemreservoir.Technical Information Series 90 Axial Piston PumpsSystem Design Parameters520L0603 • Rev 0804 • March 2016 15