jcb JS200 Service Manual page 120

Section C
3 - 7
Control, Function, Operation
CONTROL
Pump control
3
Boom lowering speed
3
regulation
4
Cushioned Boom Starting
Pressure raising system
5
3-speed travel and max. flow
6
cut
7 Cushion control
Power cut delay
8
Swing brake/swing lock
9
Lever lock (Left console)
10
Overload protection
12
Monitor display
13
9803/6400
Electrics
Layout
FUNCTION
Pump control depends on work such
as, H mode, large working load, S
mode, good fuel economy, and L
mode, for fine operation.
It also decreases boom lowering
speed in L/F mode.
Prevents shock loads when starting
to lower the boom.
Power increased when more force is
desired, or during travel.
High, middle or low speed travel
operation obtained by switch.
Performance improved during
F mode.
When cushion control is selected
shock is relieved when boom and
arm are de-selected. When hard
operation is selected, the cushion is
turned off.
A power supply is maintained to
allow electrical devices to be
operated after key switch is tuned to
OFF .
Key OFF or lock SW ON: 100%
swing brake. Key ON and operation
other than swing: 50% swing brake.
Swing operation: 0% (release).
Unless the controls are immobilised,
by raising the left console, entering
and leaving the cab is impossible.
In an emergency, it is possible to
shut off the services immediately by
raising the console.
If power transistor output of controller
is shorted, the controller is protected.
Radiator water temperature
Hydraulic oil temperature
Fuel remaining
Warning display
Section C
OPERATION
The supply current to
electromagnetic proportional
pressure reducing valve which
is built into the pump, is
regulated.
When L/F mode is selected
the boom lowering stroke of
control valve spool is
restricted.
When starting, a momentary
negative control signal is
generated.
Pressure raised by 2-stage
MRV being operated by
solenoid valve.
Selects travel motor 2-speed
positions, to give function of
restricting max. flow of pump.
Modulates movement of
control valve boom/arm
spools when they are
deselected.
After the key switch is turned
OFF there is a 5 seconds
delay before the battery relay
is cut OFF.
Pressure is maintained by a
pressure reducing valve,
dependent upon brake
selection.
With left console raised the
controls are isolated.
An overcurrent sensing circuit is
fitted within the controller. When
the output is shorted, the power
transistor output is stopped, thus
preventing an internal overload
in the computer.
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