What Is a Construction Crane?

Adapted by: Kevin-F • Edited by: Lamar Stonecypher
Updated Apr 14, 2011 • Related Guides: Remote Control

What is a construction crane, what is the purpose of this machine, and how do construction cranes work? In this article we will look at answers to all these questions...

What Is a Construction Crane?

A construction crane is a machine for lifting that has wire ropes on a wire rope drum, chains, and sheaves. Cranes are used to raise and lower objects, and also to move them in a horizontal direction. Loads can easily be moved by a construction crane that are not within the usual capacity of humans. Construction cranes are commonly used in the construction business for the relocation of materials. Cranes are also used in the transport sector for the freight loading and unloading, and in manufacturing engineering for the assembly of heavy equipment.

How Construction Cranes Work

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How do construction cranes work? Construction Cranes work on the theory of conservation of energy, implying that the energy available for the load lifting will not exceed the input energy to the machine. Actually, due to frictional and other losses, the output energy is less than the input energy. A crane system includes a horizontal beam that is pivoted at the fulcrum. The lever principle enables a heavy load at the beam short end to be raised by a small force applied at the beam long end. The mechanical advantage obtained is the ratio of the long arm length to the short arm length.

Cables enclose the fixed block, and also wind around another block that is attached to the load. When the cable is pulled by a winding machine, a force is delivered to the load that is proportional to the length of cable between the blocks and the applied force. The hydraulic cylinder is used to lift the load, or move the beam that has a lifting device. A construction crane must be stable when managing the lifting, or horizontal movement of loads. If the soil is soft, the outriggers may sink and can cause the crane to tumble. Therefore, the design of a crane must ensure that the crane can manage the loads for which designed, and it should remain stable during its operations.

image credit: wikimedia.org

Tower Crane

A tower crane is securely fixed to the ground, or attached to the structure. Towe

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r cranes possess an excellent grouping of lifting capacity and height, and are extensively used in construction. The load is suspended from the jib, and the counter-jib holds a counterweight, normally of concrete blocks. The crane operator sits in a small cabin at the tower top, or operates the crane from the ground by remote control. The operator controls the crane by working in combination with a rigger who uses hand signals, for assisting the operator. The rigger is responsible for the crane and load safety. Tower cranes are the main equipment that is plainly noticeable on a construction site. It is important that the tower cranes are installed, and operated strictly in accordance with the specified instructions. Any negligence in crane safety may lead to serious disasters.

image credit: wikimedia.org

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