Cranes are the towers that use cables, pulleys, and a scoop or hook to lift and lower a payload. They are very common in construction, shipping yards, and in the manufacturing of heavy equipment. Those in construction are usually mobile or temporarily affixed where they are being used.
There are 2 methods used to control them. Many are controlled by an operator in the cab of the crane, usually enclosed within a cramped space, but a little comfort. It turns and moves with the crane. The other is by remote control. Sometimes radio, or wired in some cases. The operator is responsible for the safety of the payloads, all personnel safety around it, and other structures that could be hit by accident.
Medieval cranes
In the middle ages, cranes were used to build the great cathedrals of Europe. They were built on top of walls as they built them. They were often powered by men that ran inside of 2 large wheels on each side. They were also used in ports and shipyards in this time.
Mobile cranes
The most common crane is a steel truss or boom that extends, mounted on a strong mobile platform. They ride along rail, or wheels. The boom is hinged in one or more places and can be moved outward by the use of cables and hydraulics.
Telescopic crane
These cranes have a boom that is a number of tubes fitting one inside of another and Hydraulics are used to extend and contract them.
Tower crane
These are a modern form of balancing crane. When it’s fixed to the ground, it offers a great combination of height and lift. They are often seen when building tall buildings.
Truck mounted crane
These are portable and very balanced specialized trucks built to be portable, balanced, and usable in many general purpose ways and are on rubber wheels. They drive to the worksite, and have outriggers that extend vertical or horizontal and stabilize the crane. These use hydraulics and support the whole truck along with the hoist.
Rough terrain crane
The rough terrain crane in some ways has a lot in common with the truck mounted crane, however it is built for off-road use, and usually has the engine well protected within it’s frame. They use the same engine for everything. The outriggers have more capability to level and stabilize than their normal terrain equivalents.
Loader crane
These cranes are much more conventional and are mounted to a trailer and look more like an arm. Sometimes they are also put on truck boxes. Most of them fold up so they can be stored out of the way.
Overhead crane
These cranes are typically found in factories, suspend from the ceiling and are used to hoist and move heavy objects from one area to another via trolley tracks. Some have very heavy weight limits for moving around large multi-ton parts. They move along beams that are on the ceiling. They provide a lot of mobility for parts throughout the factory in many cases, or may be limited to certain lines in other cases.
When used for excavation, cranes are often used to move machinery which is more ideal for various excavation needs and materials. They can quickly bring bulldozers, loaders, and more right where it is needed from above. In some cases, even support lighter things providing platforms for personnel.
When it comes to bridges and other suspended building sites, cranes are irreplaceable in terms of productivity. Often materials need to be held in place so workers can fasten them together (weld, bolt, and even cement them into place). Crane operators don’t start there, though once they get there, they are well paid, and do have some job security. Without that, there would be many more dangers.
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