MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-30 - Manual (Page 43)

Changing the Water Flow
Model 505.20 - 505.30 SilentFlo™ HPU Operation 43
1. Check the temperature gage to ensure that the hydraulic fluid is actually
overheated. If not, the overtemperature switch may need replacement.
2. If necessary, cool the hydraulic fluid as described in this section.
3. Determine if the hydraulic fluid is receiving adequate cooling.
• The auto-cooling circuit provides a path for circulating hydraulic fluid
through the heat exchanger during periods of high pressure operation
with low demand by the system. Verify the operation of the auto-
cooling valve.
• The cooling water inlet temperature affects the efficiency of cooling
the hydraulic fluid.
• Check the cooling water inlet-to-outlet pressure differential. It should
be between 0.24–0.34 MPa (35–50 psi). Adjust the water pressure at its
source.
4. Press the Reset button to clear the interlock and turn the indicator off.
Cooling the
hydraulic fluid
If the HPS shuts down due to overheated hydraulic fluid, you may need to
perform the following procedure to circulate hydraulic fluid through the heat
exchanger to cool the fluid:
1. Open the HPU cover to monitor the temperature gage of the hydraulic fluid.
2. Turn the High/Low/Start switch to the Start position and hold it there. This
overrides the interlock and runs the pump motor.
3. Continue to hold the High/Low/Start switch in the Start position to
circulate the hydraulic fluid through the heat exchanger. Observe the
temperature gage.
4. Release the switch when the fluid temperature falls below 53°C (128°F).
5. Press the Reset button to clear the overtemperature interlock. See your
controller manual to clear the overtemperature interlock in the controller.
6. You may want to continue running the HPU to cool it off even further. Turn
the High/Low/Start switch to the Start position (the High/Low/Start
switch returns to the Low position). Continue to run the HPU in the low
pressure mode until the hydraulic fluid is sufficiently cooled.
Dirty filter
The Dirty Filter indicator lights when the flow of hydraulic fluid through the
filter is reduced. A dirty filter condition will prevent the HPU from being started,
but it will not stop the HPU while it is running.
1. Replace the hydraulic fluid filter.
2. Press the Reset button to clear the interlock and turn the indicator off.
Changing the Water Flow
The flow of water is the only way to maintain the temperature of the hydraulic
fluid. The water-regulating valve, located on the water inlet line of the HPU,
senses the hydraulic fluid temperature and automatically controls water flow to
the heat exchanger.