A crane, which is equipped with a derrick or tower, is used to lower and lift materials with the use of pulleys and cable. Heavy equipment manufacturers and the construction industry use cranes in various activities connected with their process. Cranes used in the construction industry are mostly temporary structures either mounted on a vehicle which is built for the specific purpose of carrying the crane, or fixed to the ground.
Cranes may be controlled by various methods such as radio control, infrared control or a built in control station using a push button pendant or by an operator sitting in the cab of the vehicle.
A standardized hand signal is used between the person operating the controls and the workers in the ground. Bigger installations use radio communication for this purpose. Loads can be positioned with great precision using such signals by experienced crew of the crane. Crane vessels or ships often carry the largest revolving cranes. For more info visit http://www.just-cranes.info
It is a surprise to note from the carved stone relief in Hateriis tomb of 1st century Rome, which depicts a monument being built with a sort of crane, that cranes...