SECTION 5 - HYDRAULICS
5-10
3121784
5.4
HYDRAULIC SYSTEM PUMP AND PRESSURE
LINES
The machine hydraulic system is powered by two pump
units:
•
Pump unit connected to the diesel engine, two
pumps 6,67cc/rev each, diesel engine is calibrated at
maximum 3200 rpm
•
Pump unit connected to the electric 12V motor, two
pumps 2,15 cc/rev each, electric motor is calibrated at
1500 rpm
NOTE:
Lithium machine are equipped with two pump
units, one connected to the electric motor with two
pumps 3,15 cc/rev each and the emergency 12V
pump.
All of the pump unit pressure lines are conveyed through
the hydraulic manifold into two pressure lines A and B. Six
one-way valves avoid oil under pressure to flow back to
the tank through an unused pump unit.
Every time that hydraulic oil tank is opened (depressur-
ized), such as in case of hydr. oil filter replacement, it must
be pressurized again (with cork screwed) at minimum
rpm, to avoid cavitation.
"A" pressure line sends oil under pressure to the deviator
valve, this valve is commanded directly by the control
module to feed right side ground valve-block or to aerial
part valve-block. Deviator valve normally (when not fed)
send oil to aerial part valve-block, so that it feeds right
side ground valve-block only when its coil is energized.
Its coil is not energized (oil to the aerial part) only when
machine is OFF or when machine is stabilized.
"B" pressure line sends oil under pressure to the double
pump valve that normally feeds the left side ground valve-
block.
Double pump valve normally (when not fed) sends oil to
left side ground valve-block, so that it send oil to the devi-
ator only when its coil is energized.
While "N" or "RABBIT" speed are selected, when some
boom manifold movement is in progress, double pump
valve is fed by the control module in order to feed also
with the second pump the boom manifold valve-block,
increasing the movement speed even without increasing
the RPM.
Which movement are speed up by this way depends on
which power system is used on that moment, diesel
engine, electric motor or lithium electric motor for lithium
machines, they are those movements that are better per-
formed with an higher oil rate, for instance telescope
opening is always carried out with both the pumps.
Double pump valve is not fed with contemporaneously
movements and is not fed at minimum speed "TURTLE".
5.5
GROUND COMPONENT HYDRAULIC SYSTEM
The ground control manifold valves control, outriggers,
left and right track drive, and track widening.
The ground control valves are controlled by a hydraulic
valve-block equipped with one maximum pressure valve,
six proportional valves and an ON-OFF valve for ground
control movement.
On each ground manifold oil rate is controlled through the
proportional valve managed by the control module.
Depending on the movement required, proportional valve
will open accordingly regulating the oil rate, at the same
time the relevant ON-OFF valves (one each movement)
will open feeding the relevant cylinder or drive gear
motor.
Ground manifold maximum pressure valve has to be cali-
brated as indicated on use and maintenance manual, at
200 bar with Diesel engine or 180 bar with electric motor
(185 bar for lithium machine).
When the proportional valve coil is not energized, oil flows
back to the tank.
5.6
OUTRIGGERS
Outrigger cylinders are controlled by the ground valve
block. When machine is setup on outriggers, oil is kept
under pressure on the cylinder bottom side, against
machine weight, by four piloted one-way valves installed
in series on the cylinder valves block.
Another piloted one-way valve is installed on the stem
side.
While cylinder movements are in progress the opposite/s
one-way valves is/are piloted to open letting oil flow back
to the valveblock.
5.7
DRIVE GEAR MOTORS
Each drive gear motors runs forward or backward inde-
pendently. Drive gear motors are controlled by the ground
valve-block and each one is equipped with an automatic
brake that is hydraulically deactivated only while it runs.
Drive gear motors are equipped with a second speed sys-
tem, indeed they are variable capacity so that they can
perform two different hydraulic speeds in order to change
tracks speeds further that rpm regulation.
The second speed block contains the coil in charge to acti-
vate the second speed, selecting RABBIT from remote con-
trol button the control module will energize that coil.
When that coil is energized oil is sent to both drive gear
motors to move their plate so that their chamber capacity
will be reduce. With reduced capacity the gear rate is
increased so that the tracks speed is increased too.
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