Gantry Cranes ~ these are sometimes called portal cranes and
consist basically of two A' frames joined together with a cross member on which transverses the lifting appliance. In small gantry cranes (up to 10 tonnes lifting capacity) theA' frames are usually
wheel mounted and manually propelled whereas in the large gantry
cranes (up to 100 tonnes lifting capacity) the `A' frames are
mounted on powered bogies running on rail tracks with the driving
cab and lifting gear mounted on the cross beam or gantry. Small
gantry cranes are used primarily for loading and unloading
activities in stock yards whereas the medium and large gantry
cranes are used to straddle the work area such as in power
station construction or in repetitive low to medium rise
developments. All gantry cranes have the advantage of three
direction movement †
Transverse by moving along the cross beam.
Vertical by raising and lowering the hoist block.
Horizontal by forward and reverse movements of the whole
gantry crane.
Cranes