Cranes are the type of material handling devices that operate in intermittent motion. The crane structure consists of a load-bearing part, i.e. a bridge that moves along the crane tracks and an electric or manual chain hoist or a winch that travels over the bridge, moving loads vertically or horizontally. The range of movements that the load can make is limited by the length of the track and the span of the bridge. This lifting equipment allows the handling of very heavy loads, which is why it finds its application in production plants, in transport, as well as in the warehouse and transhipment industry.
Cranes can be divided according to different categories. If we are talking about classification in terms of design features, we should mention first of all overhead cranes, where the load-bearing part rests directly on the upper track, and underslung cranes where the bridge hangs from below on the bottom of the track.
We divide overhead cranes into two subcategories – single-girder and double-girder overhead cranes. Underslung cranes are divided in the same manner.
In addition, we can distinguish:
- Gantry cranes – the load-bearing part rests on the track using supports
- Semi gantry cranes– one side resting on a track and the other side resting on a trestle bridge
- Cantilever cranes – the load-bearing part has a shape of the cantilever,
- Column cranes – with an extra column
- Modular cranes – lightweight, consist of semi-closed modular profiles and pending suspension system that is attached directly to the ceiling. The crane is easy to rebuild due to this construction.
We can also divide cranes regarding the way they are controlled. This division includes overhead cranes controlled from the cab, the ones controlled from the working level, and controlled wirelessly or automatically.
Which of the technical parameters are the most important?
Q [t] – lifting capacity. This is the largest load weight that a given crane can lift in specific conditions. The lifting capacity also includes the weight of loading devices, such as grippers, traverses, etc. The hook and other non-removable crane components are not included.
H [m] – lifting height. This parameter indicates the height from the working level up to the gripping device at the top. For overhead traveling cranes, the lifting height is calculated from the ground level.
L [m] – crane span, i.e. the distance between the axes of the running rails.
Lifting / lowering speed – in meters per second. This value applies to a load with a mass equal to the crane capacity during lifting.
Chain hoist / winch travelling speed – also in metres per second. This value determines the speed that the device can reach when traveling on a plane with a load (with wind speed below 3 m / s.)
Work intensity group FEM (ISO) – From A1 to A8 range. It all depends on the number of cycles and the load condition of the device over a certain period of time.
What are the crane operator’s responsibilities?
The main task of the person occupying the crane operator’s position is to move loads using this lifting device. It must operate the gripping device (hook) with precision. It is important that he can also handle the elements used for secure fastening of the load. The operator is also responsible for the technical condition of the entire crane and equipment used at work.
Is the crane operator’s work safe?
Every labour work is associated with a certain group of threats. The operator may be bothered by factory noise or bad lighting. On the other hand, if you work outside, changing weather conditions can be unpleasant. The risk is also associated with excessive physical exertion or spending many hours in one position. The biggest danger is being crushed by a heavy load. However, if we stick to the principles of health and safety, such work will not pose any threat to us.
The wide use of cranes means that they are used in virtually every line of business. These structures can be found in larger warehouses, halls and production plants. Cranes are widely used in industries, such as metalworking, furniture, agriculture, Automotive, and food industries.