overhead crane

Also known as a "suspended crane", this type of crane works in the same way as a gantry crane but without uprights. The hoist is on a trolley which moves in one direction along one or two beams, which move at right angles to that direction along elevated tracks, often mounted along the side walls of an assembly area in a factory. Some of them can lift very heavy loads.

Overhead cranes are used in many industries to move heavy and oversized objects that other material handling methods cannot. These cranes have a railed support structure called a bridge, and a wheeled trolley that travels across the bridge horizontally. Several varieties of overhead cranes exist including gantry, semi-gantry, cantilever gantry, storage bridge and wall cranes.

The advantages of cranes :

• Higher hook lift, since the hook can be pulled up between the main girders.
• Extremely rigid box girder construction and durable trolley design are well suited for heavy service applications.
• Light weight = lower wheel loads (less building steel)
• Low head room monorail hoist
• Lower production costs
• Ease of maintenance
• Ease of installation

Inspection Requirements - safety requirement :

Due to the large and heavy objects often being transported by overhead cranes, routine inspections are necessary to ensure continued operation of the crane and the safety of the employees around the crane. An initial inspection of the crane prior to initial use of new and altered cranes is necessary.

Once placed into service, overhead cranes will require two different types of inspections. Frequent inspections are done at daily to monthly intervals, while periodic inspections are completed at monthly to annual intervals. The purpose of the two inspection types is to detect critical components of the crane and to determine the extent of wear, deterioration or malfunction.

Items to be Inspected -

Hoisting and lowering
Trolley travel
Bridge travel
Limit switches, locking and safety devices
Load test of not more than 125% of rated load