Reference
Only
HOISTS
MLC650 SERVICE/MAINTENANCE MANUAL
5-40
Published 09-09-16, Control # 229-09
DRUM 6 LUFFING HOIST
Drum 6 Brake Overview
A brake is attached to the drum motors, with the brake discs
attached to the drum shaft. The brakes are controlled by
joystick movement and the drum park brake switch.The
brakes are applied by spring force and released by hydraulic
pressure.
The brakes must be fully released to allow the drum to rotate
for hoisting and lowering operations. To accomplish this, the
brake pressure must be above 10,5 bar (153 psi). Any
pressure below this could cause the brakes to remain
partially applied, which could damage the drum brake
system.
If brake hydraulic pressure or electrical control is lost, the
brake is applied by spring force.
Hydraulic flow to the drum 6 brake release solenoid valve is
provided by the main and charge pressure hydraulic flow
from pump 1.
Drum 6 Brake Operation
.
The J2 joystick sends a 24 V
DC
output to the drum 6 park
switch. The drum park switch is closed in the UN-PARK
position, causing the switch to send a 24 V
DC
signal back to
the J2 joystick. The J2 joystick communicates the un-park
brake command to the CCMC11 control module via the
controller area network bus (CAN Bus).
The CCM-10 control module energizes the drum 1 / drum 6
selector solenoid valve, located in the accessory valve
manifold. When energized, the solenoid valve routes
hydraulic fluid to the pilot controls of the pump 1 charge
pressure pilot valve and drum 1/ drum 6 diverter pilot valve.
The charge pressure and diverter pilot valves shift position,
allowing pump 1 main and charge hydraulic pressures to be
present at the drum brake release solenoid valve.
The charge pressure check valve only allows flow from the
charge pump when main pump pressure is not present.
When the CCMC11 control module receives the un-park
command from the J2 joystick, the CCMC11 control module
sends a 24 V
DC
output to the drum brake release solenoid
valve, energizing the solenoid. This causes the solenoid
valve to shift position, routing hydraulic fluid to the drum
brake piston, releasing the brake.
When the brake switch is moved to the ON-PARK position,
the park switch is open, sending a 0 V
DC
signal back to the
J2 joystick. The J2 joystick communicates the on-park brake
command to the CCMC11 control module via the CAN Bus.
When the CCMC11 control module receives the un-park
command from the J2 joystick, the CCMC11 control module
sends a 0 V
DC
output voltage to the drum brake release
solenoid valve, de-energizing the solenoid. This causes the
solenoid valve to return to the default position, allowing the
fluid in the brake piston to flow through the drum brake
release solenoid valve, and back to the tank. The reduced
hydraulic pressure allows spring force to apply the drum
brake.
Drum 6 Motor Loop Flushing
.
Loop flushing of the drum 6 motor occurs whenever the drum
1/drum 6 selector solenoid valve is energized. The loop flush
circuit receives flow in two sources:
•
Main pump flow when the motor is being driven
•
Charge pump flow when the motor is not being driven, or
if main pump pressure is too low
The charge pressure check valve (3) only allows flow from
the charge pump when the main pump pressure is more than
0,35 bar (5 psi) lower than the charge pressure.
CAUTION
Possible Machine Damage!
When raising or lowering a load, do not use the drum park
switch to stop the load movement, since this could cause
damage to the boom. Use the joystick for a controlled
smooth stop.
Содержание MLC650
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