Doosan DX225LC, Manual, Page: 61 / 136

Electrical System SP000935
Page 60
Operation
1. Power Mode
This mode should be selected for high-speed work. In this
mode the engine output is most efficiently utilized because
of the discharged oil volume being controlled based on the
equivalent horsepower curve at various loaded pressures.
The e-EPOS controller compares the target engine speed
with the actual engine speed and controls the signal to the
E.P.P.R.
(Electromagnetic Proportional Pressure
Reducing) valve which in turn varies the pump output
quantity.
If the load increases, the engine speed will fall below the
rated speed. When this occurs, the controller senses this
decrease and immediately reduces the pump discharge
volume to maintain the engine speed at the rated level.
On the other hand, if the load is decreased the controller
increases the discharge volume of the pump to maintain
the engine speed at the rated level.
By repeating these control operations, the engine speed is
maintained at the rated speed so maximum power can be
generated.
In Power Mode, the e-EPOS controller receives engine
speed signals from the engine control dial and the engine
controller (ECU) and converts it to an operating signal
current and is then transferred to the pump's E.P.P.R valve.
At this time the E.P.P.R. valve converts the electric signal to
the corresponding control pressure and sends it to the two
pumps, adjusting the pump discharge volume to the
desired level.
ARO0260L
Figure 52