Hydraulic cranes are heavy equipment used primarily for lifting. There are two basic necessities of their design: they must be able to lift a certain amount of weight and they must be able to do so while remaining stable. While cranes have been used throughout the centuries these days they feature a more technical design and there are several different types available. Each type of crane has its own strong points and weaknesses and as such is best suited towards certain types of applications. It is important to understand things when purchasing them so you have a good chance of making the right choice.
In order to lift such heavy loads, hydraulic cranes make use of three important parts, the lever, the pulley, and the hydraulic cylinder. The lever is basically a horizontal beam that acts as the fulcrum. When a heavy object is loaded onto the smaller end it may be lifted using a relatively small amount of force that is applied to the opposite end and in the opposite direction. Next there is the pulley, also known as a jib, which is a tilted strut that supports a pulley block. This fixed block has cable wrapped around it several times which is either pulled by hand or a machine. This way a force equal to the weight of the load is able to be created by using a mechanical advantage. Finally there is the hydraulic cylinder which lifts the load either directly or indirectly.
There are several different types of hydraulic cranes, and knowing the differences between them can help you to choose the best one for you.
- The railroad crane – is largely used for maintenance work on railroads, as such it has flanged wheels so it may travel upon the tracks. There are simple ones that may be mounted onto a rail car, or more complicated models that must be custom designed.
- The tower crane – is a modern balance crane that can be either fixed on the ground or attached to buildings or other structures. They are typically chosen for their height and lifting capacity and are an essential part of constructing tall buildings.
- The self erecting crane – is a special type of tower crane that can actually lift itself from the ground which allows the next segment of crane to be placed. Thus they can be assembled easily without outside help.
- The telescopic crane – uses a number of tubes fitted one inside the other in its boom. A hydraulic system extends and compresses these tubes so that the overall length of the boom may be altered. These are best for short term rescue or construction jobs.
- The manual crane – is not in use as much since newer models of hydraulic cranes which use electricity are available. However they are still sometimes used when power would not be possible or cost effective.