A crane is a machine that is intented to lift and lower heavy items such as materials and to move them horizontally. The machines are designed in such a fashion that they use a mechanical advantage (similar to ie a lever) and are able to move loads well beyond the normal capability of a man or even a simple machine-powered hoist. Besides their use in construction, they are also used at shipyards, loadings bays, ... for the loading and unloading of freight and in the manufacturing industry for the assembling of heavy equipment.
Types
The most widely used type is the tower crane. The counterweight for this is often designed to be at the lowest point, and connects to the arm in some way, ie in the front or middle[1], or at the back [2]. The counterweight can also be mounted directly on the arm, at the back[3].