Maeda CC1485S-1 - Functions of Moment Limiter

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2.4.2 FUNCTIONS OF MOMENT LIMITER
• Do not remove, disassemble, or repair the detector. In
addition, do not reposition the
detector from the original location to another.
• When an object hits the detector or damage is found on it, be sure to check the operating
condition of the automatic stop.
If any abnormality is found in the operation condition of automatic stop, be sure to repair
it.
• The slewing operation does not stop automatically when the crane is overloaded. When
overloaded, do not perform slewing operation.
• When the crane is ap
proximating the stop position during boom operation, be sure to
lower the boom operation speed.
If the boom is at a high operation speed, it may exceed the predetermined stop position
and the machine may tip over causing severe personal injury, which could lead to death
or serious injury.
The moment limiter is a device that is installed to prevent dropping of the suspended load or
breakage or tipping of the machine, which may occur due to overload.
Before starting crane operations, be sure to inspect operation of the moment limiter to make sure
that there is no abnormality.
[1] MECHANISM OF MOMENT LIMITER
The moment limiter knows the current posture by the boom
angle meter and boom length meter and calculates "Rated
total load" in the current condition by further knowing the
number of wire falls (input by a driver).
When the load is hoisted actually at this time, the moment
limiter calculates the "actual load" (hoisted load) according to
the pressure value from the pressure sensor of the derricking
cylinder section. The moment limiter makes comparison and
calculation on "Rated total load" and "Actual load" (hoisted
load) that were calculated in the current figure. Then, it issues
an alarm if the result is as follows: "Actual load / Rated total
load = 90 to 100%".
If the calculation result is "Actual load / Rated total load =
100% or more", the moment limiter issues an alarm and at the
same time automatically stops the boom operation.
The overload stop accuracy satisfies the stop accuracy of the
following formula by slowly lowering the boom.
Stop
accuracy =
A - B
×100＜+10%
B
Where, A: Total weight of suspended load + hook + hoisting attachment (Slings etc)
B: Rated total load of working radius (actually measured radius) where the boom stopped
due to overload