DEMAG DC-II Operating And Maintenance Instructions Manual page 90

OPERATING AND MAINTENANCE INSTRUCTIONS
4. To decrease the lowering speed, gradually release the down push button when the load
approaches the ground.
Take into account the possible preset deceleration ramp.
5. Fully release the down push button when there is slack in the lifting accessory but before
the lifting device hits the load.
6.6.6 Combining the movements
It is possible to combine trolley traversing, lifting, and lowering movements but there are
limitations to the combined movements:
•
Before starting to combine movements, ensure that you understand how the crane behaves in
each direction individually. Different cranes have different driving characteristics.
•
To reduce load swing, do not combine vertical movements (lifting or lowering) with horizontal
movements (trolley traversing).
•
Do not attempt to coordinate more movements than you can safely and confidently control. To
safely control simultaneous actions, requires good observation, concentration, and
coordination skills.
PERSONAL INJURY HAZARD
Failing to observe the movement of the crane and load could cause serious injury or
death.
Do not allow anything to divert your attention from the load and the movement of the
crane.
NOTICE
Lowering the load during trolley movements accelerates load swing.
6.6.7 Detaching a load
1. Detach the load from the hook by hand.
Never try to use the product movements to detach the load from the hook. The safety latch
on the hook should prevent this.
6.7 Slipping clutch operation
The chain hoist is equipped with a slipping clutch that activates automatically when an overload
occurs. If an attached load is heavier than the rated hoist capacity, the slipping clutch limits the
torque, which the motor of the chain hoist can apply to the lifting gear, and prevents lifting the
load.
If the slipping clutch activates already at the rated capacity of the chain hoist, the friction force
must be measured and readjusted, if needed. A qualified service technician must do the
measurement and possible readjustment of the friction force. For more information, see chapter
Adjusting the slipping clutch.
Frequency converter driven chain hoists can detect the activation of the slipping clutch by
comparing the motor frequency and the speed that is measured at the pulse wheel. If they differ
too much, the motor of the chain hoist is switched off.
6.8 Hoisting limit switch operation
When the mechanical limit switch is activated, it is only possible to move the hook in the
opposite direction. The limit stops at both ends of the chain limit the lifting height. The brake
activates automatically, and the power to the motor is turned off. Springs and buffers activate
the contact points and stop the hook motion.
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WARNING
6 OPERATION