What is the crane used for?
An overhead crane as a type of UTB is used to move heavy loads. In simplest terms, it is used to lower and raise goods vertically or horizontally via a hoist or winch. They are characterised by their simple design. They are most commonly used in industries such as transport, manufacturing or construction. When it comes to the design of an overhead crane, it is important that it has adequate strength and fatigue life. The idea is to ensure safe operation of the machine, which can be disrupted by static and dynamic loads.
Overhead cranes are used in ports, warehouses and also in transport companies. The use of cranes makes it easier and quicker to carry out work. Girders are a part of the load-bearing structure used singly or in pairs, and are usually made in the form of a welded box structure. It is possible to distinguish between a girder whose ends are supported on cranes perpendicular to them, equipped with castors. The trusses, together with the girder, are made of steel of adequate strength. The connection between the cranes and girders enables the longitudinal movement of the crane bridge relative to the substructure.
The winch/ hoist/ winch system is responsible for performing the vertical lifting movement. The most important traction systems are steel cables or chains. Overhead travelling cranes with rigidly guided hoists are also common. The mechanisms for implementing the travel movement are based on working in two mutually perpendicular directions. . This creates the conditions for the working space. As far as the electrical installation is concerned, the most common methods used are cable ducts (cable curtains) and cable guides. Cable curtains are flexible cables mounted on cable trolleys, which form a system mainly for powering a hoist or winch. In contrast, the most common for gantry cranes are cable curtains, which are fed to devices suspended from the crane hook, such as an electromagnet.
Components of cranes
Mechanical equipment of the crane:
- Overhead cranes - drive wheels, running wheels, crane driving mechanisms, buffers, copper brushes, wind protection, -only when cranes are installed outdoors
- Driving carriage - motor, gearbox
- Bridge constructed of T-bar, includes buffers
- Crane track - buffers and cams
- Lifting mechanism - hook, bar with buffers and limit switch, rope guide ring, body
Electrical equipment of the crane
- Control pendant
- Trolls - power pick-ups
- Limit switches
- Control and distribution cabinet placed on the driving trolley
- Power switch - responsible for switching the crane on and off
- Electrical switchboard located on the bridge
- Crane switch - used to switch the crane on and off, excluding auxiliary circuits
There are different types of cranes. The differences relate, for example, to the type of drive Overhead cranes can have electric, hydraulic, manual and also pneumatic drive. There are also mixed drive models.
Types of cranes
There are four main types of crane:
Overhead crane - mainly installed in industrial halls. The operator has the option of operating from the ground or from the operator's cab, which gives him freedom and access to the most complex areas.
Gantry crane - is most often installed outdoors, for example at railway sidings. They can have two or more gates and have wheeled or rail chassis. A linkage moves on the platform.
Suspension crane - usually consists of a single rail. It takes up little space in the hall and allows optimum use of the room. Compared with overhead travelling cranes, they have a lower installation height.
Half gantry crane - the operation of this type of crane involves intermittent movement....
At the outset, we should match the type of crane to the type of work to be performed and familiarise ourselves with its lifting capacity. In cranes, we use tonnes, while in double-girder cranes, it is not only the value of the main hoisting capacity and the value of the auxiliary hoisting capacity.
Markings on the crane
Directional pictograms, which are available in several colours and must be understood by those in the area of operation of the device, are placed in a clearly visible position. Examples of markings and their correct interpretation:
- Black and white - the crane is controlled via a control pendant or from a cabin
- Red-green, blue-yellow - refer to how to control the crane using the radio
The colour scheme is not coincidental. The arrow marking relates to the direction in which the hoist is moving. The arrows at 45 degrees are related to the direction of travel of the crane bridge. Modern cranes marked with virtual warning signs are also available on the market. Installed lights on the crane will display the point or area where the machine is in operation.
In order to operate cranes, it is necessary to have the relevant qualifications, which can be acquired by training at a professional centre and by passing the relevant examination. The course prepares you for employment as an operator. The most important thing is the safe operation of this equipment. In addition, knowledge of the regulations Health and Safety will translate into a reduction in the risk of occupational accidents and can also contribute to increased productivity. During his/her work, the crane operator must remember to follow all health and safety procedures and rules to ensure that the work he/she performs does not cause danger to him/her or others. The operator is prohibited from:
- Perform work under the influence of alcohol or other intoxicating substances, as well as drugs impairing mental and physical performance
- Use of mismatched or damaged slings
- Lift loads with people on them
- Lift loads in excess of the permissible appropriate load capacity of the equipment
- Perform duties with an inoperative device or without a valid UDT decision
- Use load overload protection
- Leave the load on the gripping device
- Carry loads over other people and near workplaces
- Carry out unauthorised repairs or adjustments to the unit or its components.
- Clean or lubricate the crane mechanisms during operation