MTS Hydraulic Power Unit Model 506-92 - Manual (Page 23)

Service 3-11
11. Press Pump 2 Select on the HPU Control Panel.
12. Press Start to run the HPU at low pressure, then press High Pressure.
13. Turn the pressure control on pump 2 clockwise until output pressure
on the pressure gage reads approximately 100 psi (0.5 MPa) lower
than the pressure control 1 setting.
N O T E A differential pressure between the pressure setting of
pump 1 and pump 2 prevents crosstalk between the two
hydraulic circuits
After you have
finished Replace the plastic caps removed in step 3.
Whenever the output pressure is changed, the accumulator precharge
must also be checked (see Subsection 3.1.3).