MTS Series 505 SilentFlo Hydraulic Power Unit Model 505-11 - Manual (Page 46)

Model 505.07/.11 SilentFlo™ HPU 46
Adjusting the Auto-Cooling Level
Operation
An incorrect adjustment may cause one of two conditions:
• An over-temperature 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 following procedure assumes that Steps 1 through 3 of “Adjusting the HPU
output pressure level” have already been completed.
1. With the HPU running in high, loosen the nut on the Auto-Cooling Valve
located on the control manifold (see the previous figure).
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.
While adjusting the Auto-Cooling Valve, listen to the pump. 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.
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.