LOAD LIMITING DEVICE - LIFTING MOMENT LIMITING
DEVICE “INTELLIGENT TYPE” (optional)
A characteristic which permits the classification of cranes is their lifting
capacity or maximum lifting moment. The moment is defined by the
value obtained from the product of the load to be lifted (in kg) by its
distance (in meters) from the centerline of the crane rotation.
LOAD
LIMITING DEVICE
The device called “load limiting device” utilizes a small main pressure valve insered
on the safety check valves of the crane inner and outer rams and of the jib outer
ram. Whe the intervention values are reached, these valves are activated, permit-
ting the slow descent of one of the two, or both, lifting rams (or of the jib outer ram,
when fitted) and preventing use of the crane in an overloaded condition. To stop the
load descent, it is compulsory to raduce the load radius towards the column, opera-
ting the control lever to re-enter the boom extension rams of the crane (or of the
extension when fitted) or with an alternative manoeuvre which reduce the moment
on the column axis.
(!) This operation must be carried out within and not over 5 seconds
from the beginning of the load descent.
(!) 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.
LIFTING MOMENT LIMITING DEVICE “INTELLIGENT TYPE”
(optional)
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 maxi-
mum established value. This device is fitted close to
the distributor, whose specific functions it uses. It utili-
ses an electrohydraulic technology, preventing any
movement which causes an increase in the pressure
induced by the load in the inner and outer rams of the
crane (and in the outer ram for the hydraulic extension
if fitted), up to the “critical values” which have been
established in the structural test. These values, which
are non-exceedable, determine the intervention levels
and provide the data for setting the device.
The lifting moment limiting device concernes the following
manoeuvres:
— Inner boom descent; the inner boom lift is controlled
by the general main pressure valve of the distributor.
— Outer boom lift.
— Outer boom descent.
— Extension of extension boom sections.
— Winch rope lift (if fitted).
—
If hydraulic extension is fitted: extension outer boom lift.
— Extension outer boom descent.
— Extension of the jib extension booms section.
The device is based on hydraulic controls which are activated
when the intervention value is reached and block the move-
ments of the relevant distributor levers in one or both direc-
tions. Please remember that the device will return the
lever of the element being used to neutral
position.The condition of intervention is operated by
the position of the outer boom (or, if hydraulic exten-
sion is fitted, the position of the extension outer
boom), on which the electronic signal position (mer-
cury level switch) is read by a special electrovalve.
This determines the controls of the locking or
unlocking (resetting) of the controls concerned.
The crane configurations (fig. 8a-b-c) (and the eventual
hydraulic extension) indicate the manoeuvres which are allowed and not allowed
by the device, in connection with the horizontal position of the crane and exten-
sion outer booms.
LOAD LIMITING DEVICE -
LIFTING MOMENT LIMITING
DEVICE “INTELLIGENT TYPE”
F 240
14
c VIII
fig. 8 a
fig. 8 b
fig. 8 c
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