MTS Series 505G2 SilentFlo Hydraulic Power Unit Model 505G2-30 - Manual (Page 52)

Model 505G2.20 - 505G2.30 SilentFlo™ HPU 52
Adjusting the Auto-Cooling Level
Operation
Important Adjustment of the auto-cooling valve to a level too close to the
desired output pressure may cause an unstable condition
characterized by rapid valve shifting. This condition will produce an
audible flutter and can be seen as an erratic movement of the
needle on the pressure gage.
Adjustment of the auto-cooling valve at or above the desired output
pressure may prevent the valve from shifting and result in the HPU
overheating.
Adjustment of the auto-cooling valve that results in the valve
shifting at a level substantially below the desired output pressure
may result in reduced flow to the system.
4. Confirm the auto-cooling valve setting by slowly cycling the HPU Output
Pressure Control.
A. Decrease the HPU output pressure and note a decrease in pump pitch
when the valve closes. At the point when the valve closes, the pressure
on the gage will momentarily hesitate during the adjustment.
B. Increase the pump output pressure to the desired pressure setting and
note an increase in pump pitch when the valve opens. Once again the
pressure gage will show a momentary hesitation when the valve opens.
5. If necessary, repeat Steps 2 and 3 until the auto-cooling valve is stable and
the HPU cools properly.
6. After the final adjustment, hold the HPU Output Pressure Control to
prevent it from moving while tightening the nut to secure the setting.
7. Verify that the output pressure remained at the desired level.
8. Hold the Auto-cooling Valve stem to prevent it from turning while
tightening the nut to secure the setting.
Other reasons to
adjusting the auto-
cooling valve
Adjust the auto-cooling valve if:
• The HPU shuts down due to an overtemperature condition that has
been determined to not be caused by a fault in the heat exchanger
circuit or
• If the HPU fails to deliver the full flow of the HPU to the external
circuit.
1. With the HPU running in high and the HPU set for the desired output
pressure, loosen the nut on the Auto-cooling Valve located on the control
manifold.
2. Adjust the Auto-cooling Valve setting by slowly turning the valve
clockwise. If the valve shifts, a sudden change in pitch will be heard from
the pump.
A. Reversing the valve adjustment a number of times will aid in
identifying the proper setting.
B. Make a final counter-clockwise adjustment. An increase in pump pitch
will be heard that corresponds with the opening of the valve.