Maximum
pressure
is the highest intermittent pressure allowed under any circumstances. Applications
with applied pressures between rated and maximum require factory approval with
complete application, duty cycle, and life expectancy analysis.
Minimum low
loop pressure
must be maintained under all operating conditions to avoid cavitation.
All pressure limits are differential pressures referenced to low loop (charge) pressure.
Subtract low loop pressure from gauge readings to compute the differential.
Servo Pressure
Servo pressure is the pressure in the servo system needed to position and hold the pump on stroke. It
depends on system pressure and speed. At minimum servo pressure the pump will run at reduced stroke
depending on speed and pressure.
Minimum servo pressure at corner power holds the pump on full stroke at max speed and max
pressure.
Maximum servo pressure is the highest pressure typically given by the charge pressure setting.
Charge Pressure
An internal charge relief valve regulates charge pressure. Charge pressure supplies the control with
pressure to operate the swashplate and to maintain a minimum pressure in the low side of the
transmission loop.
The charge pressure setting listed in the order code is the set pressure of the charge relief valve with the
pump in neutral, operating at 1800 min
-1
(rpm), and with a fluid viscosity of 32 mm
2
/s [150 SUS].
Pumps configured with no charge pump (external charge supply) are set with a charge flow of 30 l/min
[7.93 US gal/min] and a fluid viscosity of 32 mm
2
/s [150 SUS].
The charge pressure setting is referenced to case pressure. Charge pressure is the differential pressure
above case pressure.
Minimum
charge
pressure
is the lowest pressure allowed to maintain a safe working condition in the low side of
the loop. Minimum control pressure requirements are a function of speed, pressure,
and swashplate angle, and may be higher than the minimum charge pressure shown
in the Operating parameters tables.
Maximum
charge
pressure
is the highest charge pressure allowed by the charge relief adjustment, and which
provides normal component life. Elevated charge pressure can be used as a
secondary means to reduce the swashplate response time.
Charge Pump Inlet Pressure
At normal operating temperature charge inlet pressure must not fall below rated charge inlet pressure
(vacuum).
Minimum charge inlet
pressure
is only allowed at cold start conditions. In some applications it is
recommended to warm up the fluid (e.g. in the tank) before starting the
engine and then run the engine at limited speed.
Maximum charge inlet
pressure
may be applied continuously.
Service Manual
H1P 045/053/060/068 Axial Piston Single Pumps
Operating Parameters
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©
Danfoss | June 2020
AX152886481964en-000405