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What is an overhead crane and what is it used for?Need help related to this topic?
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What components does an overhead crane consist of? What can be done to increase safety during crane operation? Check it out!
An overhead crane is a device that is used to implement material handling in many areas of industry - from construction to manufacturing to logistics and warehousing. Familiarization with the structure and operation of an overhead crane is important for the safety of the operator and those in the area of operation of the device. What components does an overhead crane consist of?
An overhead crane belongs to the group of cranes. These are devices that are used to move a load in material handling (that is, transport with a limited range, taking place over relatively short distances). Overhead cranes can be used to lift and lower bulky loads, as well as move them in a horizontal direction. The device operates in intermittent mode, with the ability to cover a wide area in buildings and outdoor areas. Overhead crane structures consist of structural components, as well as mechanical and electrical equipment.
Overhead cranes are rarely available in bulk. Most often, they are custom-made devices manufactured for an individual enterprise, the design of which takes into account the technical and construction conditions found, the type of work performed and the specific requirements of a given technological process.
In the basic construction of cranes can be distinguished:
The structure of the crane is made of sheet steel. The main element is the bridge, i.e. the girders (single or double) usually appearing in the form of an I-beam or welded box structure. The girders rest on perpendicularly positioned cranes, with the connection allowing the bridge to move along the ground. Thanks to the castors, the cranes (and therefore the entire crane structure) can move along the track. The technical parameters of the girders and cranes must be selected so as to provide the structure with adequate strength and resistance to static and dynamic loads.
The crane is equipped with a mechanism for lifting and lowering the load, which can be in the form of a hoist, winch or winch system. The tendon is most often made of steel cable or chain. The winch (hoist) is connected to a cart made of a motor and gearbox, which allows the load to be moved along the bridge of the crane. Thanks to the cart and the face castors, the crane allows the load to be moved in two perpendicular directions. A large area on the work site can be served in this way, provided the track is properly distributed.
The crane can move up to a distance of several hundred meters, which is due to the electrical power supply realized by means of buses (single or box) installed along the track. The structure is equipped with trolleys (current collectors), which draw electricity from the rails. Flexible cables called cable curtains are responsible for powering the hoist cart, although cables placed in a plastic cable guide can also be used here. Some cranes are also equipped with cable retractors, which can be used to power an electromagnet located on the winch.
Overhead crane controls can be wired, wireless (radio) or automatic. For relatively small and infrequently used cranes, control cassettes are used. This solution also works well when the operator can move freely in the working area of the crane. If the work requires the operator to be very precise and stay in the load storage area, then most often the control is done remotely (the transmitter is in the cassette, while the receiver is on the crane). In the case of overhead cranes operating continuously and handling bulk goods, the control most often takes place in the control cabin (this form of control also provides greater comfort for the operator).
Overhead cranes are equipped with a number of additional accessories and equipment, which can be divided into two groups. In the first, you can specify elements that make the crane more functional and better adapted to the specifics of the technological process. In the second group are elements that increase the safety of the operator and other people who may be in the area of operation of the crane. Some elements are permanently mounted (e.g. buckets, electromagnets), while others can be removed and put on as needed (e.g. fork slings).
Elements that increase the functionality of the crane:
Safety brakes, sound and light signals, capacity limiters, and systems related to the movement of the crane are responsible for reducing the risk of accidents in the crane's working area, among other things. An example of a safety system is overhead crane warning lights, which emit light signals at the location of the load. The light can take the form of straight lines, points and circles. With such marking, workers become more aware of the dimensions of the load and know where it will be put down. Serious accidents involving workers being hit or crushed by a moving load can thus be avoided. What's more, the operator gains greater comfort and easier control of the crane.
The design of an overhead crane consists of a bridge set on supports that can move along the track. This makes it possible to transport the load even over a distance of several hundred meters. The movement of the load can also take place in a direction perpendicular to the movement of the crane bridge, which is possible thanks to the use of gripping elements embedded in the carts. Unfortunately, moving loads pose a danger to workers in the working area of the crane. Therefore, it is worthwhile to use additional equipment that, for example, prevents accidents in ports, and increases the functionality of the crane and the comfort of the operator.