Reference
Only
HOISTS
MLC650 SERVICE/MAINTENANCE MANUAL
5-10
Published 09-09-16, Control # 229-09
DRUM 2 MAIN HOIST
Drum 2 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.
During lowering operation, the main hydraulic flow from
pumps 2 and/or 4 is supplied to the drum 2 brake release
solenoid valve.
During hoisting operation, the charge pump flow from pumps
2 and/or 4 is supplied to the drum 2 brake release solenoid
valve.
Drum 2 Brake Operation
for the following.
The J2 joystick sends a 24 V
DC
output to the drum 2 park
switch. The 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).
In the default state, the right travel/drum 2 selector solenoid
valve (11) and the drum 2/drum 3 selector solenoid valve
(12), located in the accessory valve manifold (1), are de-
energized. The drum 3 park switch must be in the ON
position for this to occur.
With the selector solenoid valves (11 and 12) de-energized,
the pumps 2 and 4 charge pressure diverter valves (2 and 6)
are in the default position, allowing charge pressure from
pumps 2 and 4 to be present at the drum brake release
solenoid valve (18).
During drum 1 operation, the CCM-10 control module
energizes the right travel/drum 2 selector solenoid valve.
The right travel park switch must be in the ON position for
this to occur.
When energized, the solenoid valve routes hydraulic fluid to
the pilot control of the right travel/drum 2 diverter valve (5)
and the pump 4 charge pressure diverter valve (2). The
diverter valves shift position, allowing the pump 4 main
hydraulic pressure to be present at the brake release
solenoid valve and the pump 4 charge pressure present at
the charge pressure check valve (10).
If the main pump pressure drops to less than 0,35 bar (5 psi)
of the charge pressure, the check valve opens, allowing
charge pressure fluid from pumps 2 and 4 to flow to the
brake release solenoid valve.
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. The solenoid valve shifts
position, routing hydraulic fluid to the drum brake cylinder,
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 on-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 cylinder 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.
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.
Summary of Contents for MLC650
Page 1: ...R e f e r e n c e O n l y Service Maintenance Manual Manitowoc MLC650 ...
Page 2: ...R e f e r e n c e O n l y ...
Page 4: ...R e f e r e n c e O n l y THE ORIGINAL LANGUAGE OF THIS PUBLICATION IS ENGLISH ...
Page 375: ...R e f e r e n c e O n l y ...
Page 376: ...R e f e r e n c e O n l y ...