Common types and causes of crane loss accidents

A crane loss accident refers to an incident where heavy objects such as loads and lifting gear fall from the air during lifting operations, resulting in personal injury or damage to equipment. Loss accidents are the most common and relatively serious type of lifting machinery accidents.

1. Rope detachment accident

A rope disengagement accident refers to a casualty or destructive incident that occurs when a heavy object falls off and scatters from the bound hoisting rope. The main cause of the rope detachment accident is the improper binding method and key points of the heavy object, which leads to the heavy object slipping off. Improper selection of the hoisting center of gravity can lead to uneven loading during hoisting or cause the heavy object to fall off due to unstable hoisting center. The lifted load may sway due to collision, impact, vibration, etc., resulting in the loss of heavy objects, etc.

2. Decoupling accident

A hook disengagement accident refers to an incident where a heavy object, lifting rope or special lifting gear comes out of the hook opening, resulting in the loss of the heavy object. The main cause of the hook disengagement accident is the lack of a hook guard device on the hook. The function of the hook protection device has failed. It is caused by improper hoisting methods and excessive opening due to deformation of the hook opening.

3. Rope breakage accident

The main cause of the breakage of the lifting rope is mostly overloading lifting, which breaks the steel wire rope. The malfunction of the lifting limit switch caused overwinding and broke the steel wire rope. Oblique lifting and pulling can cause tangled ropes to crush and cut the steel wire rope. The breakage accident of steel wire ropes caused by fatigue deformation, wear damage, etc. due to long-term use and lack of maintenance and care, and still being used when they reach or exceed the scrapping standard.

The main reason for the breakage of hoisting ropes is that the hoisting Angle is too large, > 120 degrees, which causes the hoisting tensile strength to exceed the limit value and break. Improper selection of the type and specification of hoisting steel wire ropes, or still using steel wire ropes that have reached the scrapping standard to bind and lift heavy objects, can cause the hoisting ropes to break. There are no protective measures such as gaskets at the contact point between the hoisting rope and the heavy object, which leads to the cutting of the steel wire rope at the sharp corners and causes the hoisting rope to break.

4. Hook breakage accident

A hook breakage accident refers to the loss of heavy objects caused by the breakage of a hook. The main causes of hook breakage accidents are often defects in the hook material. The hook, due to long-term wear, has a reduced cross-section and has reached the scrapping limit standard but is still in use or frequently overloaded, resulting in fatigue damage and even breakage.

The main cause of lifting machinery loss accidents occurs in the lifting mechanism's lifting and winding system. Besides rope disengagement, hook disengagement, rope breakage and hook breakage, the fixation at both ends of each lifting steel wire rope is also very important. For instance, whether the limit safety turns of the steel wire rope on the drum can be guaranteed to be more than two turns, and whether there is a descent limit protection Whether the structure for fixing the steel wire rope on the drum device with the pressure plate and the wedge block is safe. In addition, accidents where the steel wire rope comes out of the groove (from the rope groove of the drum) or from the pulley (from the pulley) can also lead to loss accidents.