MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-11 - Manual (Page 48)

Model 505.07/.11 SilentFlo™ HPU 48
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.
3. Adjust the Auto-Cooling Valve by slowly turning the valve counter
clockwise. When the valve shifts a sudden change in pitch will be heard
from the pump. Reversing the valve adjustment a number of times will aid
in identifying the proper setting. Make a final counter-clockwise
adjustment, an increase in pump pitch will be heard that corresponds with
the opening of the valve. Stop adjusting at this point.
4. Confirm the Auto-Cooling Valve setting by slowly cycling the HPU Output
Pressure Control. 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.
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 the output pressure remained at the desired level and the nut to secure
the setting.
A. Hold the Auto-Cooling Valve stem to prevent it from turning while
tightening the nut.