There are several different types of gantries used in manufacturing, including single-girder gantries, double-girder gantries, and semi-gantry cranes. Single-girder gantries are the most common type and are typically used for lighter loads. Double-girder gantries are used for heavier loads and have two parallel beams that are supported by four legs. Semi-gantry cranes are similar to single-girder gantries but have one end supported by a leg and the other end supported by a wall or column.