Horizontal jib crane hook header to trolley luffing tower crane to prevent the lifting hook rose to the highest position with load at the bottom of the car collision, the lifting mechanism set on hoisting height limiter, GB5031 "tower overweight machine" 220.127.116.11 regulation, to the car luffing tower crane, the top hook device rises to a minimum distance of the bottom of the car frame is 800 mm, should be able to immediately stop the lifting movement, but shall have the falling movement.
Exist in the process of practical operation of tower crane, hoisting height limiter failure, the driver and failed to stop the hook upward movement, can form the top hook device collide with the lower part of the car frame (also called a header), tend to be pulled by header, hoisting wire rope hook, together with the lifting of heavy things falling from a height, the consequences are very serious, such as hook header of hoisting wire rope snap hook to fall accident in the construction site.
There are usually several reasons for this:
1. The crane will relax after long operation of the internal parts, such as the screw on the limiter.
When the limit device is relaxed, the screws above can't be in better contact with the limiter.
That would have a punch.
2. Since each device has its own service life.
If it is not checked on time, long-term accumulation causes the limiter to hide more hidden dangers, resulting in a burst.
3. If the connector of the limiter does not have the adhesive to relax.
When the limit device fails, the hook can be flushed.
4. Since the crane was installed, the staff did not modulate the sequence of the controller.
The touch point of the limiter will be hidden, and the impact will be generated.
5. Even if there is no problem in installation, pay extra attention when using it.
Some missteps can also cause a punch.