MTS Series 505G2 SilentFlo Hydraulic Power Unit Model 505G2-30 - Manual (Page 51)

Adjusting the Auto-Cooling Level
Model 505G2.20 - 505G2.30 SilentFlo™ HPU Operation 51
An incorrect adjustment may cause one of two conditions:
• An overtemperature interlock as indicated by the front panel indicator.
A mis-adjustment of the auto-cooling valve may prohibit the flow of
hydraulic fluid across the heat exchanger
• Unexpectedly reduced system performance. A mis-adjustment of the
auto-cooling valve may reduce the full flow of the pump to the external
circuit
The auto-cooling valve is factory set for an output pressure setting of 21
MPa (3,000 psi). If the HPU will be operated with a 0.2 MPa (25 psi) or larger
decrease (or increase from a lower set pressure) for a period exceeding 10
minutes, an adjustment to this valve will ensure that neither of these conditions
occurs. The auto-cooling valve is located on the control manifold.
Adjusting the auto-
cooling valve to
correspond with a
change in HPU output
pressure
Perform the following procedure whenever the HPU will be operated with a
change in output pressure for longer than 10 minutes.
The procedure assumes that Steps 1 through 3 of “Adjusting the Hydraulic
Pressure” have already been completed.
1. With the HPU running in high, loosen the nut on the Auto-cooling Valve
located on the control manifold.
2. Adjust the Auto-cooling Valve to shift at the desired level.
• When increasing the output pressure, adjust the Auto-cooling Valve
clockwise to the desired shift level.
• When decreasing the output pressure, adjust the Auto-cooling Valve
counterclockwise to the desired shift level.
Note The number of turns required to reach the transition level will depend on
the how much the output pressure is changed. For example, going from
an output pressure of 21 MPa (3000 psi) to 14 MPa (2000 psi) may
require as much as three full turns on the auto-cooling valve before you
approach the transition level.
3. While adjusting the Auto-cooling Valve, listen to the pump.
A. When the valve shifts a sudden change in pitch will be heard from the
pump.
B. Reversing the valve adjustment a number of times will aid in
identifying the proper setting.
C. Make a final counter-clockwise adjustment, an increase in pump pitch
will be heard that corresponds with the opening of the valve.
D. Stop adjusting at this point.
An alternative to listening for a change in pump pitch is to hold the return line
hose at the manifold while making the valve adjustment to feel when the
resultant flow stops or starts.