jcb JS300 Service Manual page 174

Operation
Operating Levers/Pedals
Left Joystick
The left hand joystick controls the slew of the superstructure and the movements of the dipper. When released,
the joystick returns to the neutral position.
The superstructure will slew within its limits for as long as you hold the joystick over to one side. It will stop
automatically when you release the joystick due to the application of the slew brake.
When the joystick is returned to neutral, the machine will still not stop moving immediately because of inertia.
Remember this when you do a slew operation. The operation of the bucket attachment is reversed when it is
installed in the reverse position, be careful.
To slew to the left, move the joystick to the left (position 1).
To slew to the right, move the joystick to the right (position 2).
The dipper will move within its limits as long as you hold the joystick forward or backwards. It will stop
automatically when you release the joystick.
To move the dipper outwards, move the joystick forwards (position 3).
To move the dipper inwards, move the joystick backwards (position 4).
Press and hold the boom priority switch to change the priority from slew to boom raise. Release the switch
to deselect boom priority.
Select the boom raise priority option during a simultaneous slew and boom operation to decrease the flow to
the slew motor and increase the flow to the boom raise operation.
Auxiliary hold is particularly useful when continuous prolonged hydraulic flow is required. To activate, move the
joystick slider away from the neutral position and then momentarily press button A. This will store the position
for continuous hydraulic flow. Press button A again to de-select the stored position.
Press the horn switch to sound the horn, to give a signal before the machine is started or before you engage
travel or slew.
The proportional auxiliary control (high flow) switch is a variable position switch, spring loaded to the central off
position, it supplies bi-directional flow for the relevant attachments, for example weed cutter, grab rotate. Press
and hold the switch to the right or left, as applicable, for as long as the attachment is to be used. Release the
switch to turn off the attachment. The rockbreaker/auxiliary foot pedal can be used but with on/off functionality
only.
On machines with a 'Supershort' dipper or a 'Triple Articulated Boom', the bucket can foul the boom when the
dipper is moved inwards. Be careful when you move the dipper inwards.
99 9831/1100-2 99