• Do not remove, disassemble, or repair detectors. Do not move the detectors to another
location from original position.
• Should an object hit a detector or you find any damage on a detector, be sure to verify the
actuation status of the auto stop. If you find any abnormality with the actuation of the auto
stop, do not fail to fix it.
•The machine will not stop automatically even if the crane is overloaded during the slewing
operation. Do not slew the crane when being overloaded.
• When the boom approaches the stop position during the operation, be sure to change the
operation speed of the boom to low speed.
With high-speed boom operation, the boom may overrun the specified stop position, causing
serious accidents such as overturning of the machine resulting in death or serious injury.
• The moment limiter emergency stop cancel switch will
temporarily disable the moment limiter function. While
this switch is turned to ON position (i.e. released),
calculation of the rated total load is stopped, thus the
machine is in a very risky condition. When lifting
operation is continued in this condition, it may result in
dropping of the hoisted load or damage to the boom, and
cause serious accidents such as overturning of the
machine resulting in death or serious injury. Use of this
switch must be limited to the specific inspection and
maintenance purpose, where each sensor to detect the
crane condition is checked.
Otherwise, keep the key of the switch extracted, for ordinary operations. When turning ON
(cancel) the emergency stop cancel switch, always shift the crane speed to low.
The moment limiter is a device installed to prevent the hoisted load from falling, the boom from breaking,
or the machine from overturning due to overloading.
Always check the operation of the moment limiter before crane operation to verify no abnormality.
[1] MECHANISM OF MOMENT LIMITER
The moment limiter calculates current "rated total load" by knowing
the current boom posture by the boom angle gauge and the boom
length gauge, and by knowing the number of wire falls (entered by
the driver).
Then by actually hoisting a load, the "read load" (hoist load) is sent
from the pressure sensor of the derrick cylinder to the moment
limiter.
The moment limiter comparatively calculates between the "rated
total load" computed out of the current posture and the "real load"
(hoisted load), and issues an alarm if the result indicates the rated
total load/real load=90 to 100%.
If the calculation result indicates the rated total load/real
load=above 100%, an alarm is issued and the causes the boom
operation to automatically stop.
And the accuracy of the overload stop meets the accuracy calculated as below, when the boom is slowly
lowered:
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