MTS Model 512-14 Hydraulic Power Unit - Manual (Page 29)

Checking the Hydraulic Fluid
512.14 Hydraulic Power Unit Maintenance 29
Checking the Hydraulic Fluid
Hydraulic fluid contamination and deterioration normally occur in most
hydraulic systems. Failure to keep your fluid sufficiently free of contaminants or
to change the fluid before severe fluid breakdown occurs will cause poor system
performance and may lead to expensive system cleanups. Servovalves are
especially susceptible to damage from dirty hydraulic fluid.
To avoid these problems, you must maintain a clean hydraulic system. Regularly
test samples of your hydraulic fluid and follow the recommended maintenance
procedures described here. For more information on hydraulic fluid care, refer to
the MTS Hydraulic Fluid Care Guide.
Important To prevent problems with inconsistent and inferior fluids, MTS
recommends only Mobil DTE 25 or Shell Tellus 46 to its
customers.
Procedure Perform the following visual and olfactory checks of the hydraulic fluid's
condition weekly. If you suspect contamination of the hydraulic fluid, take a
sample and have it analyzed.
1. Check the fluid level in the HPU sight gage to verify the fluid level is
correct.
• A low level can indicate a leak. If necessary, add enough fluid to bring
the reservoir level up to the proper operating level.
• A high level can indicate water contamination from the heat exchanger.
2. Check the hydraulic fluid color. Clean hydraulic fluid is amber in color.
Keep a sample of brand-new hydraulic fluid in a clean glass container for
comparison. A change in color can mean that the fluid is contaminated or
that it has broken down chemically. Refer to the table,
“Appearance of
Hydraulic Fluid Sample,” on page 33 if the hydraulic fluid appears different
than the clean sample.
3. Check the smell of the hydraulic fluid. Burnt-smelling hydraulic fluid can
indicate a chemical breakdown.
If you detect a distinct change in the smell of hydraulic fluid, have it
chemically analyzed by the manufacturer.
4. Keep records of the maximum reservoir temperature.
High operating temperatures can cause the fluid to break down. If your
records indicate a pattern of overheating, consult your MTS Field Service
Engineer to determine if changes or adjustments to your hydraulic system
are required.