jcb JS300 Service Manual page 710

100% Swing Lock
K Fig 14. ( T
For schematic,
When the Swing lock button is operated in the cab, the
MECU gives two outputs:
1 To the 2 swing shut off solenoids 44. This blocks both
swing pilot signals preventing the signal from
reaching the swing spool;
at the same time both sides of the swing spool are
opened to tank preventing swing left or right from
operating.
2 To the CT3 solenoid on the 8 Station solenoid valve
60, allowing any pressure in the Swing brake to drain
to tank.
The CT1 Swing brake solenoid is de-energised as soon as
the Swing lock button is pressed.
Note: The CT3 solenoid is energised either, 5 seconds
after the button is operated, or 5 seconds after the Swing
pressure switch opens, depending on which is last to
operate. This allows the Swing to come to a standstill on
the cross line relief valves, before the brake is applied.
E-49
E-50).
9813/5100-1
Section E - Hydraulics
Hydraulic System
Hydraulic Operation and Schematics
E-49