16 MANOEUVRES OF THE CRANE LOADS
16.1 Generality
(!) ATTENTION (!)
Before manoeuvring the load, verify that the working area is suitable for
your crane.
The lifting curves of the capacity plate indicate the maximum load that the
crane can lift at a certain radius and at a certain height. To utilize the maximum
capacity of the crane, it is necessary to position the inner boom as indicated
on the capacity plate. During load handling, do not exceed the reach limits
given, or the load indicated on the above mentioned charts. If the limits are
exceeded, the limiting device, allowing all manoeuvres, which reduce the lifted
load within the permitted reach limits and forbid all other manoeuvres,
will be immediately activated.
Lifting moment limiting device
A characteristic which permits the classification of cranes is their lifting capa-
city or maximum lifting moment. The moment is defined by the value obtained
from the weight of the load to be lifted (kg) by its distance (meters) from the
centreline of the crane rotation.
The device called "lifting moment limiting device" preserves the crane
structure from overloads, as it prevents any movement which increases the
value of the moment up to the maximum established value.
(!) ATTENTION (!)
The presence of the lifting moment limiting device does not release the
user from the obligation to respect what is indicated on capacity plates
and lifting curves.
16.2 Lifting moment limiting device "EVOLUTION"
(LMEV) and automatic dynamic control (ADC)
This device utilises an electro-hydraulic system managed by an electronic
logic that prevents any operation tending to cause an increase in the pressure
induced by the load in the lifting rams (inner, outer rams of the crane and of
the hydraulic extension, if fitted), up to the critical values. These values, which
are not exceedable, determine the intervention levels and provide the data for
setting the device.
The pressure values detected in the lifting rams are turned into electric signals
by the transducers, and sent to the electronic logic of the device which deter-
mines the locking or unlocking of the controls concerned, according to the hori-
zontal position of the crane outer boom; only the controls allowing a reduction
of the overload are enabled, while those increasing it are disabled.
The device features an electro-hydraulic control that does not allow the set
value to be exceeded, by deactivating the controls commanded by the limi-
ting device. When the controls are released (levers in neutral position) it's this
electronic logic that handles which manoeuvres are disabled, according to the
position of the crane outer boom and in overload condition, by sending electric
signals to special micro-switches placed on the elements of the distributor.
The ADC device (if fitted) can be activated only through the radio remote
control. It controls the dynamics of the movements by limiting the distributor
control levers run according to the pressure of the hinged rams in movement,
thus providing the maximum speed available subject to the applied load. When
using manual controls (therefore the ADC system is not enabled), the oil capa-
city is automatically reduced in order to avoid excessive dynamic solicitations.
(!) ATTENTION (!)
The ADC device is not active on winch controls and on accessories other
than the hydraulic jibs.
Practically the speed of the load movement decreases as the interven-
tion limit of the lifting moment limiting device approaches.
16
CONTROLS TO OPERATE
THE CRANE
GR4_5 - EVOLUTION
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