Overhead cranes are a standard fixture in many industrial, manufacturing and assembly environments. Cranes consist of a variety of components, which include hoists, hooks and ropes. They are devices that raise and lower a desired load and move it along a horizontal plane. This plane of movement is determined by the type of overhead crane used. The end of the load-bearing arm is attached to wall columns, referred to as "overhung," or to the underside of the ceiling, also called "underhung." Most overhead crane systems are controlled via an operator remotely or via a fixed housing control. Many of the more complex systems are fully automated, acting as part of a larger assembly system.
Gantry, semi-gantry, cantilever gantry, storage bridge and wall cranes are among the types of overhead cranes. Gantry cranes are very similar to overhead cranes with the exception of the bridge for the trolleys. Two or more legs support it as the crane runs on fixed rails or another runway. One end of the bridge of a semi-gantry crane is supported by one or more legs, with the other end attached to a truck running on an elevated rail or runway.
Gantry, semi-gantry, cantilever gantry, storage bridge and wall cranes are among the types of overhead cranes. Gantry cranes are very similar to overhead cranes with the exception of the bridge for the trolleys. Two or more legs support it as the crane runs on fixed rails or another runway. One end of the bridge of a semi-gantry crane is supported by one or more legs, with the other end attached to a truck running on an elevated rail or runway.
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Last Updated: Sep 2009
Last Updated: Sep 2009
What are Overhead Cranes?
Cantilever gantry cranes are either gantry or semi-gantry cranes on which the bridge girders or trusses extend beyond the crane runway on one or both sides. Storage bridge cranes are a type of gantry crane in which the bridge girders or trusses are rigidly or non-rigidly supported on one or more legs and may have one or more fixed or hinged cantilever ends. These long-span cranes are typically used for bulk storage applications. Wall cranes are a traveling type of crane which have a jib, with or without a trolley. These cranes are supported from a side wall or line of columns of a building to which the runway is attached.
The automotive industry utilizes overhead cranes extensively in their production facilities. These cranes are also commonly used in the construction of very tall structures. Conventional material handling methods cannot be used for the oversized loads that must be shifted in those industries. Moving heavy loads, like engines, requires the use of a heavy-duty overhead crane. Relocating cargo containers and other heavy non-assembly materials, such as blocks of concrete, is another common use for overhead cranes. Other machinery, like hydraulic lifts, is also used for the raising and lowering of loads, sometimes in tandem with overhead cranes.
Frequent inspections must be performed on overhead cranes for safety purposes. Every day the operating mechanisms should be checked for maladjustment, the pneumatic and hydraulic parts for leakage, the hooks for deformation or cracks and the hoist chains and end connections for wear, twist or distortion. The running rope and end connections should be checked on a monthly basis for wear, broken strands, etc. Periodically, the overhead crane should be checked for deformed, cracked or corroded components, loose bolts or rivets, cracked or worn sheaves and drums, other worn, cracked or distorted parts (e.g. bearings, gears and rollers) and excessive wear on brake system parts, chain drive sprockets and chains. Other components to be inspected include electric or fossil-fuel motors, indicators and electrical components, such as pushbuttons, limit switches or contactors that may be corroded. OSHA has published a set of guidelines for the safe operation of overhead cranes.
The automotive industry utilizes overhead cranes extensively in their production facilities. These cranes are also commonly used in the construction of very tall structures. Conventional material handling methods cannot be used for the oversized loads that must be shifted in those industries. Moving heavy loads, like engines, requires the use of a heavy-duty overhead crane. Relocating cargo containers and other heavy non-assembly materials, such as blocks of concrete, is another common use for overhead cranes. Other machinery, like hydraulic lifts, is also used for the raising and lowering of loads, sometimes in tandem with overhead cranes.
Frequent inspections must be performed on overhead cranes for safety purposes. Every day the operating mechanisms should be checked for maladjustment, the pneumatic and hydraulic parts for leakage, the hooks for deformation or cracks and the hoist chains and end connections for wear, twist or distortion. The running rope and end connections should be checked on a monthly basis for wear, broken strands, etc. Periodically, the overhead crane should be checked for deformed, cracked or corroded components, loose bolts or rivets, cracked or worn sheaves and drums, other worn, cracked or distorted parts (e.g. bearings, gears and rollers) and excessive wear on brake system parts, chain drive sprockets and chains. Other components to be inspected include electric or fossil-fuel motors, indicators and electrical components, such as pushbuttons, limit switches or contactors that may be corroded. OSHA has published a set of guidelines for the safe operation of overhead cranes.
