An overhead crane or a bridge crane as it is more commonly known is typically used in industries and environments where lifting of heavy loads is needed frequently. An overhead crane or a factory bridge crane has parallel runways that are connected to a bridge that can move covering the entire area of the gap. There is a hoist that is attached to the bridge and it serves as the major component that lifts loads. The hoist hooks the load and then moves it to its destination with the help of a bridge.
Factory bridge cranes can be divided into categories as mentioned below:
Under Running or Top Running
These happen to be the primary configuration for bridge cranes. Under running cranes are also known as under hung. On a top running crane, the end of the truck is attached to the top of the beam runway. Similarly an under running crane has the truck attached to the lower flange of beam runway. Both of these configurations have their own advantages.
With an under running crane you can go for a better end function using the hoist. Using an under running crane the hoist can reach the far end of the truck or even the end of the beam runway when it is actually not possible to do so with a top running crane. Also under running cranes are very cost effective because they allow for multiple tasks. You can use the hoist and transfer it along interconnected bridges and monorails.
As far a top running crane is concerned, it has its best advantage in being able to lift very heavy loads, heavier than those a normal under running crane can lift. Also a top running crane has greater headroom as compared to an under running crane.
The other configuration dividing the bridge cranes is:
Single Girder or a Double Girder Crane | Factory Bridge Crane
Both of these are a type of factory bridge crane and are very strong, rigid and durable. Both cranes are equal and have specified operations for which they can be used. What one needs depends solely upon their factory requirements when looking for a factory bridge crane.
Single girder cranes are not expensive as double girder cranes and are used to lift loads that weigh about 50 tons and their transfer span is within 35m. Single girder crane does not require any special equipment or reinforcements. They are ideal for use if you do not need greater leg width, a much enhanced work speed and you do not require lifting loads heavier than 50 tons at a time.
Where mechanization, modernization and automation of factories are concerned, double girder factory bridge cranes are the most suited to the industry. Double girder cranes are very useful when you have to lift heavy loads, greater than 100 tons at a time. It serves well for both indoor and outdoor purposes and is widely used in the railway, transportation, mining, port terminal, logistics, iron and steel industries and a whole lot of departments and industries. Double girder cranes can work for longer duration of time as compared to a single girder crane.