What are used overhead cranes, and why are they a good option for your workshop? An overhead crane is a tool widely used in industry and factories for heavy lifting. It allows very large parts to be moved horizontally and vertically.
Why buy a used overhead crane?
Used and new overhead cranes are a common sight in large factories and industrial plants, where they are as much a part of the workshop and industrial building as any other equipment. These units are used to lift and move very heavy loads. With them you can move parts, machines and pallets, among other things.
A used overhead crane consists of parallel rails mounted high up along the sides of the building and a movable steel bridge, known as the girder. But note: when the bridge is rigidly supported by two or more legs that travel on rails fixed at floor level, it is no longer an overhead crane but a gantry crane.
Unlike construction cranes or mobile cranes, used overhead cranes are installed high up on the roof structure and side walls of the building. In other words, they can only operate inside the industrial building where they are installed. Their movement is also limited by the space in which they are fitted.
Uses of used overhead cranes
These large items of equipment are generally used in the metallurgical industry and in heavy industries such as the automotive, aerospace, aeronautical and shipbuilding sectors. In the metals industry, overhead cranes are used to move finished products such as pipes, beams or coils, either for storage or for loading onto transport.
Overhead cranes are also used in the construction industry, specifically in cement production. They make it possible to manufacture pipes, beams, posts and other large, bulky products.
In the automotive industry and other transport manufacturing sectors, these cranes are essential for handling raw materials and even for the assembly of large parts and components.
Types of overhead crane
Today there are different types of overhead crane to suit the needs of each sector.
- Single-girder. Used in medium-sized industrial buildings with high ceilings. It consists of a rolled-section girder and can handle loads of between 0.5 and 25 tonnes. Lifting height ranges from 6 to 18 metres.
- Double-girder. These cranes are built with two main girders, which allow them to carry very heavy loads. They can be fitted with spatial control systems, variable speeds, maintenance platforms, walkways and hoists. Capacity ranges from 20 to 250 tonnes.
- Electromagnetic. This crane has two main girders and is ideal for handling metal materials. The electromagnetic overhead crane is fitted with an electromagnet that can exert a magnetic force on heavy objects, provided they are made of metal. It can lift from 20 to 75 tonnes to a maximum height of 16 metres.
How does it work?
An overhead crane is powered by a festoon, a cable and support system that supplies the necessary power to a trolley and hoist along the whole bridge. Power is taken from the conductor bar on the crane runway and fed to the main bridge panel, which in turn supplies all the power to the overhead crane.
The cable trolley carries power to the hoist panel and transmits it to the bridge. This allows the bridge to travel and pick up the required material. This is when the lifting and transfer of the parts across the building takes place. It is very important for the overhead crane to have a safety system in the form of a pendant control station, as well as a radio remote control; these allow the crane's movement to be controlled and accidents to be avoided.
What to consider before buying an overhead crane
If you are going to buy a used overhead crane, it is advisable to consider certain parameters of the unit. These will help you make the most of its features. In some cases, they can also be customised.
- Span. This is the distance between the centre lines of the runway beams. It indicates the width or span of the whole overhead crane.
- Trolley gauge. On double-girder cranes, the trolley gauge is the distance from the centre of one of the trolley rails to the centre of the other trolley rail.
- Headroom. This is the distance measured between the base of the hook and the underside of the trolley wheels when the hook is raised to its upper limit.