Gantry Cranes For Open Air And Windy Environment

Gantry Cranes for Open Air and Windy Environment

 

Gantry cranes working in the open air are generally affected by natural wind, especially near the seaside. When the wind is too strong, the lifting operation should be stopped.

 

When the stopped gantry crane is hit by strong wind, it may cause the crane to overcome the braking force of the brake of the traveling mechanism of the cart and slide, and the crane may tip over as a whole, causing an accident.

 

 

At present, Dejun's newly designed gantry crane (hereinafter referred to as gantry crane) has been equipped with a windproof device, and the original gantry crane has also added this device.

 

Some of these windproof devices control the driving wheel set, and some control all the big wheels. They play a somewhat positive role in resisting the threat of wind loads. However, it is necessary to prevent the attack of strong wind. To ensure the safety of the door crane, all large wheels must be controlled.

 

25 ton gantry cranes are often attacked by strong winds during operation. Therefore, the design of the windproof device must be based on the rated load, downhill, downwind operation and other conditions when encountering sudden strong winds. It must be able to withstand Concentrated 800N/m wind pressure (twelve-level wind force), because the box-shaped double-girder gantry crane has a large wind-shielding area, now we will discuss the wind-proof device by taking the 25 ton box-shaped double-girder gantry crane designed and manufactured by our factory as an example.

The windproof device can only prevent the attack of strong wind if it controls all the big wheels. When the wind pressure is less than 250N/m2, brake the driving wheels of the cart; when the wind pressure is greater than 250N/m2, brake all the large wheels to make the gantry crane stop smoothly.

 

In order to achieve this purpose, we can perform secondary braking on the door crane. Brake the active wheel set of the oversized car for the first time, and then brake all oversized wheels after a delay of 6 seconds. When the wind pressure is less than 250N/m2, the first braking has stopped the gantry crane smoothly, and the second braking can be used as a measure to prevent greater wind force.

 

When the wind pressure is greater than 250N/m2, although the first braking did not make the door crane stop smoothly, the speed of the cart has been reduced, and then the second braking can make the door crane stop smoothly. This can not only ensure the effective braking of the door crane, but also ensure the stability of the door crane.

 

 

In addition to adding the windproof device of the gantry crane, the windproof device of the gantry crane built by Dejun also added rail clamps, anchoring devices, iron shoes and so on.

 

Summarizing the past experience of 25 ton gantry cranes being blown over by the wind, the common thing is that all cranes with lifting equipment that were blown over by the wind all experienced the sliding process before overturning without exception. The gantry cranes that are blown over by the wind are often due to the lack of wind protection awareness of the user unit, and insufficient wind protection measures have been taken for the crane.

 

In order to prevent the 25 ton gantry crane from being blown over by the wind, the crane safety regulations stipulate that the crane working in the open air must be equipped with a windproof device.

 

1. Iron shoe windproof device

 

Insert an iron wedge between the wheel and the track. When the crane moves backward due to the wind, the force of the wheel rotation acts on the iron wedge, so that the rolling friction between the wheel and the track is transformed into a gap between the iron wedge and the track. The sliding friction between them, as the resistance continues to increase, effectively prevents the crane from moving and plays a windproof effect.

 

This device can be divided into two types: manual type and electric type. Among them, the iron wedge of the electric iron shoe is connected to the crane in a floating manner. Usually, the iron wedge is pressed on the track by the force of the spring. When the crane is turned on, the iron wedge is lifted under the action of the electromagnet without blocking it.

 

2. Clamp type windproof device

 

This device uses clamps to clamp both sides of the track to increase the friction of the track, thereby preventing the crane from sliding.

 

This device is also called a rail clamp. In order to improve the tightening degree of clamping, it is often designed with a lever structure. The common types are as follows: manual screw type, hydraulic spring type, electric screw type and electric weight type These four.

 

3. Anchored windproof device

 

Anchored windbreaks are a commonly used preventive device. When receiving a strong wind warning signal, or when the machine is not in use for a long time, the anchored windproof device can be used to prevent wind and slip.

 

The anchor type windproof device requires the temporarily unused crane to be driven to a predetermined position, and the crane is fastened with locking parts such as bolts and ejector rods.

 

4. Rail-type windproof device

 

This device uses the weight of the crane itself to act on the track, increasing the friction between the wheels and the track to prevent the crane from moving.

 

The pressure rail type windproof device is not affected by the side of the rail, and its applicability is stronger than that of the clamp type. However, the windproof performance provided by this windproof device is not high, and it is often used in conjunction with other windproof devices.