How It Works: Stationary Cranes
Exchanging mobility for the ability to carry greater loads and reach greater heights, due to increased stability, these types of cranes are characterized by their main structure’s immobility during the period of use. These types of cranes can be assembled and disassembled and are sometimes referred to as fixed cranes.
1. Tower Crane –Fixed to the ground on a concrete slab (and sometimes attached to the sides of structures as well), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. The base is attached to a mast, which gives the crane its height. Further, the mast is attached to the slewing unit (gear and motor) that allows the crane to rotate. On top of the slewing unit there are three main parts that include: the long horizontal jib (working arm), shorter counter-jib, and the operator's cab.
2. Self-Erecting Crane – Also called jack-up or kangaroo cranes, these types of cranes lift themselves from the ground or an upper, telescoping section using jacks to allow the next section of the tower to be inserted at ground level, or lifted into place by the partially erected crane itself. They can be assembled without outside help and can grow together with the building or structure they are building.
3. Telescopic Crane – A telescopic crane has a boom that consists of a number of tubes fitted one inside the other. A hydraulic, or other powered mechanism, extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are often used for short-term construction projects, rescue jobs, and lifting boats in and out of the water. The relative compactness of telescopic booms make them adaptable for many mobile applications.
4. Jib Crane – A jib crane is a type of crane where a jib or boom, supporting a moveable hoist, is fixed to a wall or to a floor-mounted pillar. Jib cranes are used on industrial sites and on military vehicles. The jib may swing through an arc, to give additional lateral movement, or be fixed. Similar cranes, also known as hoists, can be fitted on the top floor of warehouse buildings to enable goods to be lifted to all floors.
5. Loader Crane - A loader crane, also called a knuckle-boom crane or articulating crane, is a hydraulically powered articulated arm fitted to a truck or trailer. It is used for loading and unloading vehicles. The numerous jointed sections can be folded into a small space when the crane is not in use. One or more of the sections may be telescopic. Often the crane will have a degree of automation and be able to unload or stow itself without an operator's instruction.