SWING SYSTEM MLC165-1 SERVICE/MAINTENANCE MANUAL
6-2
Published 05-26-17, Control # 238-02
Swing Brake
The swing planetary drive has a spring-applied, hydraulically
released brake at the input of the planetary drive after the
motor. The swing brake has to be actively released by the
control system. If brake hydraulic pressure or electric control
is lost, the swing brake applies by spring force.
The main pump contains a charge pump which sources flow
to the swing brake control valve. The brake pressure must be
above 392 psi (27 bar) to fully release the brake. If the
pressure is below this, the brake could become partially
applied and damage the swing system.
Swing Brake Operation - Park Switch Control
Node 1 sends a 24Vdc output to the swing park switch. The
swing park switch is closed in the OFF- PARK position, so
node 1 reads back a 24Vdc signal from the switch. Node 4
sends a 24Vdc output to the swing brake valve solenoid,
energizing it. This causes the swing valve to shift position,
porting fluid to the brake cylinder, and releasing the brake.
When the swing brake switch is moved to the ON- PARK
position, the swing park switch is open, sending a 0Vdc
signal back to node 1. Node 4 controller sends a 0Vdc output
voltage to the swing brake valve solenoid, de-energizing it.
The swing brake valve returns to the normal position, porting
fluid back to tank and the swing brake applies.
Swing Brake Operation - Momentary Swing Brake
Control
Node 2 sends a 24Vdc output to the momentary swing park
switch. The switch is normally open, sending a 0Vdc signal
back to node 2. Node 4 sends a 24Vdc output to the swing
brake valve solenoid, energizing it. This causes the swing
valve to shift position, porting fluid to the brake cylinder, and
releasing the brake.
When the momentary swing brake switch is closed, node 2
reads back a 24Vdc signal from the switch.Node 4 sends a
0Vdc output voltage to the swing brake valve solenoid, de-
energizing it. Spring pressure within the spring brake applies
the brake.
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