A gantry is a crane used to hoist objects. This device is usually mounted on a trolley which can be rolled horizontally over a pair of rails. The ability to lift excessively heavy weights makes the gantry crane applicable in industries such as ship building and construction. Smaller gantry cranes are used in automobile workshops to lift car or truck engines out of the vehicles. Portable gantry cranes can be easily disassembled and transported from one location to another and can even be used on service trucks.

Features and working of a gantry

Most gantry cranes are made of either steel or aluminum. Some gantries are provided with rubber tires, thus avoiding the necessity of the rails. The posts are generally made of heavy gauge Square tubing. To ensure smooth movement of the gantry in a straight line, four-position phenolic resin swivel lock castors of approximately 6 x 2 inches are attached to the underside of the gantry. The average length of a gantry is around 12 to 14 feet, with the clearance between uprights being around 11 feet. Most gantries have a capacity of around 1 to 10 tons. Gantry cranes cannot be used to lift weights higher than their maximum capacity as this could lead to a breakage and danger for the operator.

Gantries are normally of three types, depending on height adjustment functionality; manual adjust, lever adjust, and fixed height models. Depending on the application and the size and shape of the object, the height of the adjustable gantry can be changed by the user, with the lower range being around 9 to 12 feet and the upper limit being around 12 to 15 feet. Adjustments can usually be made in 6 inch increments.

A kind of gantry crane, called a portainer crane, is designed by cantilevering the horizontal gantry rails and the supporting beams outwards from between the frame uprights. This crane is especially suited for ship building as the beam supporting the rails can be extended over the quayside, enabling easy lifting of objects.

High strength mechanical tubing renders added durability to the gantry. Some gantry cranes incorporate motor drives on a V groove track crane rail that facilitates the movement of the crane. Power drives are normally two-drive systems with gears. Under emergency situations, the mainline magnetic power disconnect feature enables the crane to stop instantly. A thermal overload feature ensures that overheating does not take place, thus prolonging the life of the device. An I-beam mounted plate design offers faster assembly. 

What to look for in a gantry

While some gantry cranes have a fixed height, gantries which have a variable height feature are more versatile. The body of the crane as well as the all the fasteners holding the device are made of superior, corrosion resistant materials to make the device usable outdoors, even in rough weather, exposed to the sun and rain. A gantry crane with greater flexibility as far as height is concerned is preferred as this makes the crane more maneuverable in tight locations and uneven grounds. An enamel finish to the frames minimizes the chances of chipping and scratching.

Usually steel built gantry cranes are stronger than aluminum cranes and have a lifting capacity of as much as 10 tons.  However, steel gantries are heavier than aluminum cranes. Mold-on polyurethane wheels offer easier movement of the gantry over a surface.  
Customized single or double leg wide flange beam cranes are suitable where there is need for a secondary overhead crane without any extra floor space, or an open area for vehicles and people. The castors used are normally well padded to prevent marring the surface of the floor. Additionally, efficient wheel brakes help to stop the rolling motion of the crane after it has been properly positioned. This also serves as a protective measure considering the height and weight of the device, which could cause immense damage if allowed to collide with an object or person.

Those gantry cranes working on power drives have a ‘soft start’ feature that prevents excessive torque being generated at the start of the crane, which could result in jerking of the crane and an abrupt topple.

Wesco is one of the reputed manufacturers of gantry cranes.