Gantry and semi-portal cranes are used where there is a need to serve a larger outdoor area or a combination of indoor and outdoor space, or where it is not possible to install a conventional overhead crane on the columns of the hall.
Cranes can be mobile on rails or fixed in the base, with one or both sides of the beams fitted with cracks for better use of the handling space. The crane cat travels along the main girders or is suspended underneath them; the gripping means are similar to those of bridge cranes. The control is usually from the cab, by remote control or by a hanging panel, the power supply is most often by cable on a cable drum or trolley in a parallel channel.
