Reference
Only
Manitowoc
Published 09-09-16, Control # 229-09
5-1
MLC650 SERVICE/MAINTENANCE MANUAL
HOISTS
5
55
SECTION 5
HOISTS
GENERAL
This section provides the electrical and hydraulic crane hoist
information. Electrical and hydraulic circuit schematics are
provided for each drum system.
Details of individual components are covered later in this
section. Component information can also be found in the
following sections of the Service Manual:
•
Section 2: Hydraulics
•
Section 3: Electrical
DRUM 1 MAIN HOIST
Drum 1 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 1 and/or 3 is supplied to the drum 1 brake release
solenoid valve.
During hoisting operation, the charge pump flow from pumps
1 and/or 3 is supplied to the drum 1 brake release solenoid
valve.
Drum 1 Brake Operation
The J2 joystick sends a 24 V
DC
output to the drum 1 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 left travel/drum 1 selector solenoid
valve (2) and the drum 1/drum 6 selector solenoid valve (3),
located in the accessory valve manifold (1), are de-
energized. The drum 6 park switch must be in the ON
position for this to occur.
With the selector solenoid valves (2 and 3) de-energized, the
pumps 1 and 3 charge pressure diverter valves (4 and 8) are
in the default position, allowing charge pressure from pumps
1 and 3 to be present at the drum brake release solenoid
valve (18).
During drum 1 operation, the CCM-10 control module
energizes the left travel/drum 1 selector solenoid valve. The
left travel park switch must be in the ON position for this to
occur.
When energized, the left travel/drum 1 selector solenoid
valve routes hydraulic fluid to the pilot control of the left
travel/drum 1 diverter valve (9) and the pump 3 charge
pressure diverter valve (4). The diverter valves shift position,
allowing the pump 3 main hydraulic pressure to be present at
the brake release solenoid valve. Charge pressure from
pump 3 is blocked at this time. Only pump 1 charge pressure
is available to the charge pressure check valve (13).
If the main pump pressure drops to less than 1,7 bar (25 psi)
of the charge pressure, the check valve opens, allowing the
pump 1 charge pressure fluid 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.
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.
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