MTS Series 505G2 SilentFlo Hydraulic Power Unit Model 505G2-11 - Manual (Page 52)

Model 505G2.07/.11 SilentFlo™ HPU 52
Low/High Pressure Functionality
High pressure
When the Series 505 HPUs are running in high pressure, a considerable amount
of heat is generated. During normal testing, this heat is dissipated by running the
hydraulic fluid through the system from the return line to the heat exchanger.
During periods of low system demand, this heat is dissipated by running the
hydraulic fluid through the auto-cooling circuit to the heat exchanger.
Auto-cooling
The Auto-Cooling Valve is adjusted such that the shift between valve closed and
valve opened occurs just below the output pressure level. Whenever system
pressure is above the shift level of the Auto-Cooling Valve (indicating low
system demand), the valve opens to port hydraulic fluid through the return filter
to the heat exchanger. When system pressure drops below the shift level
(indicating an increase in system demand), the valve closes and full flow is
available to the system.
The effective operating range of the auto-cooling circuit is between system
pressures of 14 MPa (2000 psi) to 21 MPa (3000 psi). In order for the Auto-
Cooling Valve to function properly, it must be re-adjusted anytime the output
pressure will be changed for longer than 10 minutes.
Note If the test condition requires a maximum pressure level less than 14 MPa
(2000 psi), consult MTS.