jcb JS200 Service Manual page 337

Section E
60 - 4
Operation (continued)
Hydraulic Slew Brake - 50% Engagement
*
When the slew lever is placed in neutral and 5 seconds have
passed, an electric signal enters the solenoid valve for slew
brake from the controller and the spool is selected. (In the
figure, it moves down-ward).
The oil of the spring cavity d of the reducing pressure spool
is connected to the tank passageway.
The pressurised oil which enters through P port flows to
gallery a , b and tries to push up the reducing spool.
The pressurised oil is throttled from gallery b and flows to e
and d and then the tank. Also, it flows from gallery b to c to
the solenoid valve for slew lock to B to the brake gallery of
the slew motor.
The reducing valve rises by a set amount only and oil enters
the brake gallery of the slew motor, applying the brake at
50%.
9803/6400
Hydraulics
Stacked (Slew Brake) Valve
*
Section E
60 - 4
Issue 2*