© MOOG 2019
This document is subject to MOOG INTELLECTUAL AND PROPRIETARY INFORMATION LEGEND . The details are on page II.
15
MRJ06301
1-5-8. THE IMPORTANCE OF FILTRATION
Adequate contamination control in any hydraulic system is the key to a
highly reliable system. Proper filter placement and selection insures
long term trouble free operation of every hydraulic system component.
There are three essentials:
1) a high pressure filter mounted directly at the tooling actu-
ator
2) a re-circulating circuit providing continuous filtration and
heat removal
3) proper control of the tank breathing and filling operations
to prevent the ingression of contaminant
High pressure filter (
β
15
»75, 15µ absolute) mounted directly with tubing
at the tooling actuator provides protection against particles created by
component failures.
The main contamination protection is provided by oil taken from one
corner of the tank, flowing through the low pressure re-circulating filter
back to the opposite corner of the tank. The re-circulation filter is a low
pressure filter (
β
3
»75, 3µ absolute) with an inexpensive replacement
filter element. The re-circulation also incorporates a heat exchanger to
maintain low oil temperature and insure adequate oil life.
Protection against ingression of contaminant during oil make up and normal breathing is provided with
breather rated at 10µ.
Currently, MOOG does not sell filters. Please purchase directly from the filter manufacturer.
1-5-9. FILTER INSTALLATION
High pressure filter or equivalent,
β
15
>75 rated, high pressure filter must be mounted as close as possible
(50mm to 300mm) to the actuator or servovalve manifold. The location of the filter must allow an easy
access to make a replacement of filter element easy and safety.
Filter Installation Information
The hydraulic connection between the filter and actuator must be tubing. Under no circumstances can
hydraulic hose be used as the hose is a contaminant generator and this contaminant will go directly into
the servovalve, eventually causing contamination problems.
The hydraulic connections used will be a straig
ht thread “O” ring sealed boss into the servoactuator and
high pressure filter with either flared or compression fittings used to connect the tubing to the straight
thread fittings.
The use of tapered thread fittings with pipe dope will cause both contamination and leakage problems.
Teflon tape may be used, but only if applied in such a manner as to keep the edge of the Teflon tape at
least two threads away from the end of the fitting.
Figure 1-13 High Pressure Fil-
ter
