MTS Series 505G2 SilentFlo Hydraulic Power Unit Model 505G2-11 - Manual (Page 56)

Model 505G2.07/.11 SilentFlo™ HPU 56
Checking the 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 Hydraulic Fluid Care Guide (part number 050-000-536).
Important To prevent problems with inconsistent and inferior fluids, MTS
recommends only ExxonMobil DTE 25 or Shell Tellus 46 to its
customers.
Procedure Perform the following checks of the hydraulic fluid 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,” 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.
5. Check and adjust the hydraulic fluid delivery system so that:
• Hydraulic fluid temperature stabilizes within acceptable limits when
the HPU is operating at high pressure.
• Pressure line reading is maintained at 21 MPa (3000 psi) maximum
static value.
• Maximum drain line back pressure is limited to 0.1 MPa (15 psi).
If you need to adjust the water-regulating valve, overtemperature switch or
pressure control valves, see the procedure for Changing the Water Flow.