Overhead travelling cranes are the mainly used for handling the equipments within a work area or work site. Double girder crane is used for safely moving materials from a certain point to the other by using a hoist that gets attached to the hoist trolley and that can move horizontally on a pair of rails or on a rail that is fitted under a beam. The overhead crane is also known as suspended crane and has got the ends of the beam that supports it resting on wheels that runs on rails at higher levels.