The hydraulic power unit is provided with a steel tank suitable for
outdoor service able to collect the full volume of oil present in
the circuit. The tank is equipped with inspection door, breather
with filter, 2 level switches, 1 temperature switch, 1 visual level
Two main motor-pump groups P1 and P2, each one fitted with an
electric motor, are provided on the tank; the fixed displacement
pump is able to deliver the required flow rate at a pressure of 200
A filtering/conditioning group composed by fixed displacement pump
P3, filter with clogging detector (DPS3) and exchanger (R) with fan
piloted by internal thermostat is provided on board.
Functions of the main pumps are :
n° 1 active pump, to maintain all control valves in closed / open
position or under continuous control.
n° 1 stand-by pump to be activated on alarm signal from low
pressure switch mounted on pump common delivery manifold
The pump flow rate is sufficient to ensure the maximum stroke time
required in control mode for each valve without involving the
Four pressure switches are installed in the common delivery
manifold of the motor-pump groups, as follows:
PS1 supplies the “low oil pressure signal"
PS2 supplies the “minimum oil pressure signal” (i.e. plant out of
PS3 stops the active pump
PS4 starts the active pump
One accumulator A1, constantly inserted on the delivery manifold,
is installed on the hydraulic power unit to grant trouble-free
change-over from a motor/pump group to the other one.
The overflow valve VS3 controls the oil pressure in the primary
Two sealed maximum pressure safety valves VS1 and VS2 are mounted
on pump deliveries.
A double filter F provided with electric clogging detectors
DPS1-DPS2 is installed at power unit outlet.
The hydraulic power unit is provided with two terminal boxes: the
first one is intended for instrument cables, the second one for the
One accumulator (20 litres) assists the pumps for control and quick
actions of the connected valves.
Solenoid valves for emergency actions and proportional valves for
control mode are installed on the hydraulic cylinder.
Accumulator (10 litres)
Pressure relief valve for accumulator with PED certification
First filling oil
Charging and testing unit for accumulators
Cabinet with PLC for HPU management (no solenoid power supply)
Servocylinders with built-in solenoid and proportional valves.