XCT80 Truck Crane Operation Manual
8-12
Components and functions of upper crane portion
Chapter 8
8-4 Safety device
8-4-1 Lifting torque limiter
8-4-2 Three-coil protector (counter)
1. Working principle
Lifting torque limiter calculates the crane
operating radius according to suspension boom
length and angle signals inputted into each
sensor. According to the input signal of pressure
sensor, the luffing cylinder force is calculated,
and then the lifting torque is calculated. Finally
comparing with the maximum stress value
stored in the database, the corresponding
information is issued through display.
2. Safety function
When the lifting torque limiter overloads,
the force limiter will cut off all action working
condition that can continuously increase torque(
stretching boom, downward luffing and lifting);
only action working condition that decreases
the torque is retained ( retracting boom, upward
luffing, off hook ).
3. lifting height limit function
Open the switch when the hook goes closer
to the lifting boom pulley head (Specific height
see Figure 5-2 Lifting height graph in Chapter
5), and after the processing of the lifting torque
limiter, the lifting boom stretching and the hook
lifting are stopped at once. At the same time,
the lifting torque limiter display alarm lamp is
brightly on.
4. The Do's and Don'ts
a. Before the lifting operation, please
carefully read “torque limiter manual".
b. Although the crane is equipped with
torque limiter, this device is not as a substitute
as the judgment of a crane operator. Practical
experience and operation according to the crane
safety operation specification are still not be
replaced by the torque limiter, and the operator
still has the responsibility for safety operation.
c. Before the operation, the driver should
know about the weight of hanging things and
compare with the lifting performance table to
select the appropriate working condition. The
torque limiter is one of the most important
safety devices of the machine, and not closed for
forbidden during the lifting operation and in not
allowed lifting working condition (e.g. stretching
boom bearing weight etc.).
The counter is also called three-coil protector.
When the crane operating plane is higher, the
hoisting mechanism steel wire rope might over
release. When the steel wire rope on the reel
remains at least three to five laps, the protector
actives, the buzzer alarms and the over releasing
alarm indicator lamp lights.
To Next Page
Loading...
