Technical Description; Drive And Brake; Gearbox And Slipping Clutch; Chain Drive - DEMAG DC-Com 1 Operating Instructions Manual

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Technical description

4.1

Drive and brake

A robust pole-changing AC asynchronous motor is used as the hoist motor. The brake is arranged on the load
side in such a way that the load is safely braked and held if the slipping clutch is tripped. The brake is released
electrically. Pressure springs ensure that the brake is applied automatically when power to the motor is switched
off or if there is a power failure. The motor is automatically switched off and, at the same time, the brake is applied
when the slipping clutch is tripped and if errors occur.
The lifting drive first decelerates by switching from fast speed (2-pole winding) to creep speed (8-pole winding).
Mechanical braking occurs when the creep lifting speed has almost been reached.
The mechanical brake is applied as soon as the emergency-stop is actuated, regardless of the lifting speed.
Wear of the mechanical brake is significantly reduced by electric and regenerative braking of the motor.
4.2

Gearbox and slipping clutch

Fig. 6 Parts in which the load is borne
4.3

Chain drive

The special Demag chain is of high-strength ageing-resistant material with a high degree of surface hardening,
galvanised with additional surface treatment. The dimension tolerances of this chain have been precisely adapted
to the chain drive. We therefore urgently recommend that the Demag special chain be used to ensure safe opera‐
tion. The maximum service life of the chain can only be reached if the specified regular lubrications are correctly
carried out. The entire chain drive is always replaced when a chain is replaced. A chain set which can be easily
replaced is available for this purpose.
The chain set offers the following benefits:
● the optimum duration of service is ensured for the chain;
● certainty that the individual chain drive components are replaced when necessary;
● reduction in service costs by replacement and installation in one step; the motor and gearbox do not need to
be disassembled.
4.4

Electric equipment

4.4.1

Control system

The chain hoist is fitted with a 24 V contactor control system. The contactor control system is supplemented by an
electronic system with programmed functions. This electronic system detects the control commands that are trig‐
gered by the operator with the control pendant. Permissible control commands generate switching commands for
the contactors to control the hoist motor. The electronic system monitors the control sequence specified by the
operator based on the speed feedback from the drive shaft, the operating limit switch contacts and, if applicable,
28
A Drives
1 Slipping clutch
2 Motor
3 Chain drive
Tab. 21
The slipping clutch is arranged between the motor shaft and the gear‐
box input shaft. In connection with the limit stops on the chain, it per‐
forms the function of the emergency limit stop device for the highest
and lowest hook position and protects the Demag chain hoist against
overload. The additional electric operating limit switches (standard for
DC-Com 10 with 2/1 reeving, optional for DC-Com 1-10 with 1/1 reev‐
ing) for the highest and lowest hook positions prevent the slipping
clutch from being approached as an emergency limit stop device during
normal operation. The slipping clutch also fulfills the EC Machinery Di‐
rective requirements for a load control device for load capacities as of
1000 kg.
The brake arranged on the load side prevents the load from slowly
dropping when the unit is at rest. Monitoring of the slipping clutch and
automatic cut-out of the drive if slip occurs increase the service life and
protect the slipping clutch against overload and incorrect use. The gear‐
box is maintenance-free for up to 10 years.
B Brakes
4 Speed detection
5 Brake
6 Gearbox