Change The Hsm Filter; 252 Servovalve; Replacing The Servovalve Filter Element - MTS Systems Landmark 370 Series Product Information

Change the HSM Filter

1. Ensure that system hydraulic pressure has been reduced to zero before proceeding. To do
this, turn off the hydraulic power unit and exercise the actuator until it stops moving.
2. Turn off electrical power at the controller.
3. Place a waste fluid pan beneath the filter housing, which will accumulate any small amount of
drainage from the filter housing.
4. Remove the inlet filter bowl.
5. Remove the disposable filter element from the filter bowl.
6. Empty the oil in the filter bowl into the pan. Wipe out any remaining sediment with a clean lint-
free cloth.
7. Inspect the O-ring in the filter housing for any sign of deterioration. If necessary, replace the
defective O-ring (part number 010-010-726).
8. Lubricate the filter element and filter housing O-rings with clean hydraulic fluid. Insert the
replacement filter element into the filter bowl. Tighten the filter bowl to 34–41 N·m
(25–30 lbf·ft).
9. Apply low, then high, hydraulic pressure to the actuator manifold and inspect the seal between
the filter bowl and housing for any signs of leakage. If leakage exists, turn off system hydraulic
and electrical power and repeat Steps 4 through 9.

252 Servovalve

Maintaining the Series 252 Servovalves typically involves changing the filter element (Series 252.3x
only) and setting the mechanical null adjustment. Except for these procedures, further disassembly,
inspection, or repair of the servovalve is not recommended and may void the servovalve warranty.
MTS does not recommend changing the 35-micron filter element in the Series 252.2x/.4x Servovalve
(revision C). MTS hydraulic power supplies filter the system hydraulic fluid at 3-microns absolute. The
system filters will trap most solid particle contaminants. If servovalve performance has deteriorated
and the cause has been isolated to the servovalve filter, return the servovalve to MTS for service.

Replacing the Servovalve Filter Element

Under normal operating conditions, the 20-micron stainless steel filter used in the servovalve should be
replaced only if servovalve performance has deteriorated. Ensure that other possible causes of poor
performance, such as plugged system filters or hydraulic power unit wear, have been eliminated
before replacing the servovalve filter.
MTS Landmark™ Tabletop Load Units - Product Information
Filter
3 micron (Beta = 75)
3
10 micron (Beta = 75) 011-395-936
7.4
Part Number Kit Number
011-395-937 044-205-301
044-205-201
Maintenance
115