Working Principle of Overhead Crane

Overhead crane, also called bridge crane, is a kind of crane traveling on the elevated track to lift goods. Overhead crane move in longitudinal direction along the erected track and its trolley move in transverse along the elevated track, which work in a rectangle scope. Crane operators can lift and transport cargo with the space under the overhead crane without being hindered by ground equipment.
 
Overhead crane is widely used for warehouse indoor and outdoor, workshop, wharf, open-air yard and etc. Overhead crane can be divided into simple overhead crane, general overhead crane and metallurgy special overhead crane.
General overhead crane is composed of crane moving system, lifting trolley and metal structure. Lifting trolley can be divided into lifting mechanism, trolley moving system and trolley bogie.
 
Lifting mechanism includes brake, motor, reducer, coiling block and pulley block. Motor and reducer bring coiling block to rotate, finally realize to lift up and down goods. Trolley bogie support lifting mechanism and trolley moving system, it is always welded.
 
Driving method of moving mechanism of overhead crane can be divided into two types: one is centralized driving, that is, one motor drive long transmission shaft to drive active wheels on both sides; the other is separately driving, that is, active wheels on both sides are driven by one motor. Middle and small overhead cranes always adopt brake, reducer and motor to combine into “three-in-one” driving method. In order to install and adjust, most of overhead crane in heavy-duty always adopt universal coupling as its driving device.
 
As for moving mechanism of overhead crane, to increase wheels can be used to decrease wheel pressure if the lifting capacity is too large. If the amount of wheels exceed four, it had better adopt device to balance bogie to keep the loads of overhead crane can be distributed to every wheels.
 
Metal structure of overhead crane is composed of main beam and end beam, which can be divided into two categories: LD single girder overhead crane and QD double girder overhead crane. LD single girder overhead crane is composed of one main girder and both end beams, QD overhead crane is composed of two main girders and two end beams.
 
Main girder and end girder are in rigid connection, both ends of end girders are designed with wheels to support the overhead crane moving in the elevated track. There are traveling track welded to support the moving of lifting trolley.