MTS Hydraulic Power Unit Model 506-92 - Manual (Page 18)

3-6 Service
Replacing hydraulic
fluid Perform this procedure to replace the hydraulic fluid. You will need a
Model 590.01 Fluid Transfer Pump or a pump which provides at least
10-micron filtration.
HPS – Rear View
VW-G042D
drain
1. Turn off electrical power to the HPU. Remove the reservoir filler
cap assembly.
2. Drain the hydraulic fluid into a container, while hot, through the
drain valve. Close the valve.
Then drain the oil from the entire system (such as from the hoses
and accumulators).
Dispose of the fluid according to company policy.
3. Remove the top plate from the reservoir.
4. Wipe the inside of the reservoir with a clean lint-free cloth. Apply
MOBILSOL A—a solvent for cleaning and flushing hydraulic
systems—to a clean lint-free cloth and again wipe the reservoir.
Immediately wipe away the solvent with a dry cloth.
5. Replace the high-pressure filter element. See Subsection 3.1.1.1.
6. Replace the low-pressure filter element. See Subsection 3.1.1.2.
CAUTION !
To avoid damage to the hydraulic system, follow these precautions:
Do not mix different brands of hydraulic fluid.
This can create contaminants. Ensure that the replacement hydraulic fluid
is the same brand and type as the fluid which was removed. Generally, an
MTS Hydraulic Power Unit contains Mobil DTE 25 hydraulic fluid.
Consult MTS before you use alternate fluids.
Use a transfer pump that provides 10-micron or better filtration.
Most commercial hydraulic fluids exceed the maximum amount of
contamination allowable in MTS hydraulic systems.
7. Use the transfer pump to fill the reservoir with fresh hydraulic fluid.
8. To flush out the pipe line, connect a hose from the pressure line to
the return line of the last station, and operate the HPU at low
pressure for 2 - 4 hours.
9. Replace the high-pressure filter if necessary (Subsection 3.1.1.1).