Cranes form an important part of most civil engineering projects. Different kinds of cranes are utilized depending on the weight to be lifted and available area for movement. One type of such cranes is the jib crane.
A jib crane is a kind of crane that utilizes a mounted arm in lifting, moving and lowering materials. The arm, which is mounted at an acute-angle upwards from or perpendicular to a wall or pillar, can rotate along the central axis for a full circle or a limited arc. These cranes are usually used in industrial sectors, such as docks and warehouses, in loading and unloading shipping containers.
The history of a jib crane goes back to the ancient Greece, when the idea of lifting objects with a mechanical arm was commonly used. On the same note, the Romans later adopted the concept and used it in the construction of aqueducts, roads and other engineering structures. Cranes were advanced, but remained identical in designs to the classical ones till the invention of the steam engine and the industrial revolution in the nineteenth century. With the ever growing construction on both sea and land, as well as the increasing demands of shipping companies and complex factories, cranes also developed in intricacy and size during this period.
The working principle of jib crane
The fundamental idea of a crane stems from the mechanical advantage concept. Mechanical advantage refers to the principle that a machine, like a pulley, is capable of multiplying the force exerted on it by a given factor. This explains why it’s possible, for example, for one man to use a pulley to lift a heavy thing that would require a combined force of many men to lift the same load directly. A crane incorporates a wide range of pulleys with simple machines, like levers and gears, to significantly increase lifting capacity.
In the modern jib cranes, robust metal cable is wrapped around the jib strut ends, with the end of the hoist often connected to an electromagnet or hook, while the other end is connected to a metallic winch. When you activate the winch, the pulley delivers a lifting force that’s equal to the force applied by the metallic winch. The hoist can move inwards or outwards along the jib length, providing even better flexibility of motion.
A jib crane is not restricted to a fixed location and can be mounted on a movable chassis for use in military operation or other temporary work sites. Such cranes often focus more on mobility rather than lifting capacity. Outriggers are often used in mobile jib cranes to keep them stable under load. On the other hand, the stationary cranes are generally anchored in place.
Types of jib cranes
Free standing
This kind of cranes requires no support to make it stable while placed on the floor. They come with a large foundation base to keep them stable. The base and height of the foundation largely depend on the load to be lifted. The notable advantage of this crane over its counterparts is that it doesn’t require a solid structure or wall to support itself. Furthermore, it provides maximum coverage and span.
Wall mounted
Just as the name suggests, wall mounted cranes are mounted on the walls. It offers optimal lift when fitted closer to the roofs. The coverage of this jib crane is similar to that of other types of crane. It has a circular shape. It is quite effective in moving materials when the floor is jam-packed with other things.
Wall bracket
This crane is similar to its wall mounted counterpart in terms of structure and installation requirement but it’s incorporated with a bracket. This machine offers maximum hoist coverage, making it an efficient tool in warehouses and factories. It is capable of swinging loads all around regardless of obstructions and obstacles on the floor.
Mast style
This kind of jib crane is almost similar to the free standing type. The only difference is that the latter does not require any support to keep it stable. On the other hand, a mast style crane is mounted at the bottom and top but it’s one of the most efficient mobile cranes. It offers maximum lift with a 360-degree rotation.