Suction filtration
Charge pump
Filter
Hydraulic fluid reservoir
Adjustable
charge pressure relief valve
To pump case
To low
loop and
control
Manometer
P102 003E
C
Caution
Clogged filters can cause cavitation, which damages the charge pump. We recommend a filter bypass
with a filter bypass sensor to prevent damage due to blocked suction filters.
Charge pressure filtration (partial charge pump flow)
Two types of pressure filtration exist for most Series 90 pumps. The two types are: remote pressure
filtration (filter remotely mounted on vehicle) and integral pressure filtration (filter mounted to the
endcap). Verify option availability in the size specific technical information.
In either case the filtration circuit is the same with the filter element situated in the circuit downstream
the charge pump and upstream of the charge relief valve such that full charge flow is continuously
filtered, as shown in the accompanying illustrations. Charge pressure filtration can mitigate high inlet
vacuum in cold start-ups and provides fluid filtration immediately prior to entrance to the loop and the
control system. Pressure filtration provides a higher level of filtering efficiency than suction filtration.
Filters used in charge pressure filtration circuits must be rated to at least 35 bar [508 psi] pressure. A 100 –
125 μm screen located in the reservoir or in the charge inlet line is recommended when using charge
pressure filtration.
Technical data according to ISO 16889
Nominal flow at 30mm2/s and ∆P 0.5 bar[7.3 psi] (clean filter element only)
Minimum β-ratio
Short
60 l/min
β7.5(C)=75 (β5(C) ≥10)
Long
105 l/min
Remote charge pressure filtration
A special adapter head is available to allow for the charge filter to be located conveniently for easy
service and replacement. Care should be taken to minimize the hydraulic pressure drops associated with
long connecting lines, small diameter hoses, or restrictive port adaptors at the filter head or endcap.
Ensure the normal operating pressure drop across the remote filtration in and out ports is sufficiently
below the crack pressure setting of the recommended filter bypass valve.
Technical Information
Series 90 Axial Piston Pumps
System Design Parameters
14
520L0603 • Rev 0804 • March 2016
