33
21491244.p65/201204
9 Geared limit switch for the DR rope hoist
9.1 Geared limit switch
9.1.1 Determining the cut-out points
for the geared limit switch
The geared limit switch is fitted in the electrical equipment enclosure of the Demag
rope hoist.
It switches off the rope hoist when the top or bottom hook position is reached. The
direction of movement can be reversed. The emergency limit switch must not be
approached in normal operation.
Operating limit switches are required where the end positions are approached
regularly during normal operation.
In such cases, the switches must be adjusted so that the operating limit switch is
actuated first and then, i.e. if this fails to operate, the emergency limit switch.
Accident prevention regulations require that the crane operator checks the emer-
gency limit switch before starting work. This can be done using the key-operated
button in the control pendant.
The operating limit switch can be by-passed by pressing this button. In order to
approach the emergency limit switch, the hoist unit must be switched on and the
check button pressed simultaneously.
The key-operated button must be pressed in order to leave the end position
(lowering).
The functions carried out by the geared limit switch can be seen in the wiring dia-
gram provided.
The emergency limit switches must be properly adjusted to ensure prevention of
accidents and to avoid damaging the rope hoist. The emergency limit switches are
adjusted before leaving the factory to avoid complete unwinding of the rope, only.
Following installation of the rope hoist, they must be readjusted and checked for
the particular operating conditions.
If you wish to set the greatest possible lifting height for your specific operating
conditions, it is essential to observe the following:
The emergency limit switch for the top hook position must be set so that when it
switches off the lifting movement, the minimum distance between the top edge
of the bottom block and the bottom edge of the track girder is maintained (see
table 1).
To Next Page
Loading...
Need help?
General
