HOISTS MLC165-1 SERVICE/MAINTENANCE MANUAL
5-10
Published 05-26-17, Control # 238-02
To release the free fall brake, three conditions must be met:
• The hydraulic valve (5, Figure 5-6 on page 5-9
) is in the
open (on) position.
• The clutch/brake pedal is all the way down until it
latches.
NOTE When the pedal is latched down, flow from the
accessory pump to the pedal valve is routed to the
tank (no pressure to the brake).
• The free fall enable/disable key switch is toggled to the
drum 1 and/or drum 2 position. Through software, this
switch enables the FF solenoid to respond to the control
handle.
For specific operating instructions, see Section 3 of the
MLC165-1 Operator Manual.
In the open position, the manual hydraulic valve allows flow
from the brake pedal. When the operator allows the pedal to
rise, a proportional valve connected to the pedal will begin to
open, and the pressure will build in the hydraulic circuit to the
brake.
When the pedals are latched down, pressure in the circuit
will drop below 100 psi (6,9 bar). If all other conditions are
met and the free fall enable key is turned on, the control
system activates the free fall solenoid valve, allowing
pressure to reach the free fall brake. As the pedal is allowed
to rise, the brake will release and the load will begin to
descend. Full brake release occurs at 1,000 psi (69 bar).
Adjusting the slip setting on screen will limit the maximum
pressure available to the brake from the accessory pump.
When free fall is enabled, the drum control handle will
operate the same as in normal (non-free fall) operation, but
the operator must remember to use the clutch/brake pedal to
control lowering while the control handle is in center. See the
MLC165-1 Operator Manual for free fall operating
procedures.
WARNING
Falling Load Hazard
When the free fall mode is fully enabled, the load will fall
uncontrolled unless the clutch/brake pedal is applied.
Always be ready to apply the clutch/brake pedal so
lowering speed can be controlled.
If this is not done, the load can fall, possibly resulting in
injury or death.
To prevent the load from falling when free fall is selected
for a drum, latch down the free fall clutch/brake pedal.
Figure 5-7. Free Fall Brake
Item Description
1 Cooling Oil Hoses
2 Release Pressure Hose
3 Fitting for Manual Hydraulic Pump
4 Hose for Internal Drum-Powered Pump
5 Manual Hydraulic Off-On Valve
(Open position shown)
M101862
1
4
5
2
3
CAUTION
Avoid Gearbox/Brake Motor Damage
While a load is being lowered using the free fall /clutch
brake, leave the control handle at the center position.
Before using the control handle, use the free fall clutch/
brake to bring the drum to a complete stop.
Moving the control handle off center while a load is free
falling will immediately engage the motor shaft to the
planetary gears, which can result in extensive equipment
damage.
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