What Is Gantry Crane?
A gantry crane is like a big, strong robot arm that lifts and moves heavy stuff around. It’s kind of like a giant erector set with legs and wheels that can pick up things in places like factories, warehouses, and shipyards.
There are two main types: single and double girder. Single girder ones are for lighter stuff, while double girder ones are for really heavy loads. They come in different shapes, like “A,” “L,” or “U” legs.
Gantry cranes are built tough and can handle lifting things that weigh anywhere from a few pounds to several tons. They’re used indoors in places like warehouses and outdoors at docks and railroad yards. Outdoor ones have special features to handle the weather, like rain covers and wind protection.
Gantry cranes are designed in different styles with different load and lifting capacities. Their wide range of shapes and sizes makes them adaptable for any type of industrial use. The differentiation between the categories of gantry cranes is dependent on girder configuration, crane size, hoist trolley, and hoist.
Though the usual picture of a gantry crane is one of a permanent immovable lifting mechanism, there are versions of gantry cranes that are portable and mobile where the crane is moved to the items to be lifted. Since gantry cranes are available to perform a wide range of lifting jobs, each type is chosen and adapted for the conditions where it is used.
Types of Gantry Cranes
Gantry cranes can be divided by their configuration, design, and weight capacity. In many ways, these factors interrelate to determine the type of gantry crane.
Full Gantry Crane
The full gantry crane is the normal configuration of a gantry crane with a cross beam, legs, and hoist, which can run on wheels, rails, or a track. They can be mobile and portable depending on their size.
Semi Gantry Crane
A semi-gantry crane has one leg and uses a wall mounted I beam to support the other side of the crane. The composition of a semi-gantry crane includes a bridge, crane mechanism, trolley, and hoist. Semi-gantry cranes are a combination of overhead and gantry cranes and are installed indoors and outdoors. In many cases, they are installed below an overhead crane to increase work efficiency without interfering with the operation of the overhead crane.
Portable Gantry Crane
Portable gantry cranes are light weight and mounted on rubber wheels or casters. They have a lifting capacity of a half a ton up to five tons and come in varying heights and spans. Portable gantry cranes are an economical solution for infrequent lifting problems but have the same efficiency as a permanent crane. They can be moved to any location in a facility to lift or place materials.
Adjustable Gantry Crane
There are several varieties of adjustable cranes, which can be portable or fixed. They can have their height, width, and horizontal beam adjusted to meet the needs of a load. The benefits of an adjustable crane are their flexibility and convenience. Though small adjustable gantry cranes are common, larger permanent single girder types are available. Many gantry cranes, regardless of type, have aspects and characteristics that are adjustable.
Single Girder Gantry Crane
A single girder gantry crane has one bridge beam with a hoist trolley that runs on the lower portion of the crane. The components of a single girder crane include the main beam, support legs, cross beam, crane drive, controls, and hoist. Single girder gantry cranes use a variety of lifting hoists depending on the type of work and can use European hoists as well. They can be configured as semi or two leg gantry cranes and can be adapted to fit the working conditions.
Double Girder Gantry Crane
A double girder gantry crane has two girder beams that make up the bridge. It can have a top running or under running trolley and is designed for extremely heavy duty applications. Double girder gantry cranes have a strong bearing capacity, large span, and excellent stability. The lifting capacity of a double girder gantry crane can reach hundreds of tons, and this type can be semi or two leg designed with A frame legs.
Truss Gantry Crane
A truss gantry crane refers to the type of girder, legs, and cross beams of the crane that are made from connected shafts. The trolley runs on top of the truss girder and may have a driver‘s cabin. Truss gantry cranes are light weight with small wheel pressure. They have a lifting capacity of five to one hundred tons and come in different lifting heights and spans. Regardless of the construction of the girder and frame, truss gantry cranes can be designed as any of the various types of gantry cranes.
Box Gantry Crane
A box gantry crane has a four sided box as the crane bridge. The hoist trolley is attached to the bottom of the box. The design of box girder gantry cranes allows them to have a longer bridge span and greater load capacity. They can be single or double box with the double box design being used for extraordinarily heavy duty lifting. Box gantry cranes are normally installed where the installation of an overhead crane is not possible. The box style girder is mounted onto A-frame columns that rest on heavy duty wheels.
L Shaped Gantry Crane
The L shaped gantry crane is a single beam crane with L shaped legs. The design of the L shaped gantry crane legs makes it capable of handling long pieces. It is used in freight yards, railroad terminals, and warehouses. The load capacity of an L shaped gantry crane ranges between five and fifty tons, with light dead weight and small wheel pressure. It can be designed with a soft start for long travel operations; this ensures stable and smooth movement.
U Shape Gantry Crane
A U shaped gantry crane is a form of double girder gantry crane with the support legs in the shape of a “U.” The U shape design creates extra space between the legs and the double girders, which makes the design suitable for lifting large loads. The trolley fits between the two girders and can have one or two hoists. Additionally, the girders can be outreached on one or both sides to form cantilevers for the ease of loading and unloading on the cantilevers. U shaped gantry cranes can run on fixed rails with low running resistance.
Workstation Gantry Crane
Workstation gantry cranes are small and designed to lift lighter goods and materials. They are portable and mobile, designed to lift a workpiece and move it to a workbench for processing. When loaded, workstation gantry cranes remain stable and stationary. The hoist has a wire rope or chain for lifting and moving workpieces. The choice of a workstation crane depends on the type of work and the required capacity.
Gantry Crane Capacity
Gantry cranes are designed to handle a wide range of loads, from a few hundred pounds to hundreds of tons. The types of gantry cranes referred to as light duty have a capacity of one to ten tons and come with a single girder with fixed or adjustable versions.
Heavy duty gantry cranes have a capacity of thirty to over two hundred tons and are double girder rail mounted.
One and two ton
Very small and used in warehouses, workstations, garages, and workshops where light lifting is required. They have a single girder and are portable.
Five ton
A light duty crane used on cargo yards, freight yards, ports, workshops, and warehouses. They can be single or double girder in semi and portable designs.
Ten and fifteen ton
Capable of small and medium lifting applications and used where the structure of a building will not support an overhead crane.
Twenty ton
Able to lift large and small loads indoors or outdoors and comes in single or double girder designs. The single girder design is normally L shaped.
Thirty ton
Come in several designs and are capable of medium to heavy lifting. They are available in a wide range of types, sizes, and configurations.
Fifty ton and greater
The beginning of the exceptionally heavy duty capacity cranes. They come in double girder designs.
How Gantry Cranes are Made
Whether a gantry crane is a small mobile one or a huge one for use in a shipyard, its components are divided into three categories: mechanical, structural, and electrical. All gantry cranes have girders or beams that are positioned off the floor or ground and are parallel to the ground or floor.
Though some gantry cranes can be attached to a building, all of them have legs that can be a straight beam, truss beam, or A frame. The girders, beams, and legs are the essential parts of a gantry crane and differentiate them from overhead or bridge cranes.
How Gantry Cranes are Made
Frame
The structure of a gantry crane consists of its main girder or beam and its legs. In the case of a semi-gantry crane, the structure is a beam and one leg. The beam is the main support for the load. The size, length, and number of beams varies depending on whether the gantry crane is light or heavy duty and the weight of the load. In regard to the legs, one side is rigid while the other is flexible to reduce deadweight and account for span deviation.
Trolley
The trolley moves the hoist horizontally along the girder of the crane and may be attached to the top or the underside. The three types of trolleys are low, normal headroom, and double girder.
Trolleys with spacing washers can be adjusted to fit the beam by adding or removing washers. Screw adjustment trolleys use a screw mechanism to do adjustments. Wheel bumpers prevent trolley wheels from colliding with other equipment while side guide rollers keep the trolley from wobbling.
Hoist
The hoist on a gantry crane is a form of winch mounted on the trolley to lift and lower the load along a vertical plane, and it moves back and forth with the movement of the trolley. Hoists that are chain driven are capable of lifting up to five tons, while wire rope hoists can lift five tons or greater.
Reeving describes the configuration of the wire rope or chain and the blocks and drum of the hoist. The various types of reeving effect the headroom, lifting speed, and capacity. The headroom is the distance from the beam to the hook. The terms single or double refer to the number of ropes or chains.
Power
A festoon is the form of wiring that delivers power to the trolley and hoist. The provided power comes from the busbar, or receiving station, to be distributed to the bridge panel to power the crane. Cables send the power from the panel to the hoist and bridge drives to run the hoist, trolley, and bridge. The power for a gantry crane can be direct AC, induction AC, or synchronous.
Controls
The controls of a gantry crane give the operator direct control of the crane‘s movements and the hoist. There are several varieties of crane control methods, ranging from wired or remote control for a small sized gantry crane to cabins and booths where the operator rides on the crane or sits in a location to observe crane movement.
The popular trend in gantry crane operations has been to move the operator out of a cabin and have them operate the crane from the ground. In those situations, the operator uses a pendant or remote radio control that has buttons, levers, or other command mechanisms to move and position the gantry crane.
Uses for Gantry Cranes
Gantry cranes are one of the many types of lifting mechanisms fitted with a trolley and hoist to move heavy materials and loads. The popularity of gantry cranes is due, in addition to their excellent lifting capacity, to their many varieties, from those that are small for a workshop to those that are giant for shipyards.
The flexibility of gantry cranes makes them a valuable tool for small and large industrial use. A gantry crane is usually used in place of an overhead crane, which may not fit the needs of an application.
Uses for Gantry Cranes
Manufacturing
Gantry cranes are widely used in industrial manufacturing to lift and move materials, supplies, and products. All varieties of gantry cranes are an essential part of the auto, steel, and aircraft industries due to the nature of their production processes. In the auto and aircraft industries, gantry cranes are part of the installation and placement of engines.
Repair Shops
In small engine repair shops, the engines to be repaired have to be lifted and positioned so that the technician can view all parts of the engine. Large overhead cranes and simple winches are either impractical or insufficient to do the job. For this reason, repair shops depend on portable gantry cranes that have the load capacity to lift an engine and the mobility to reposition it.
Shipyards
The area where large heavy duty cranes are used the most is shipyards; they are used to move extremely heavy loads and ship parts. Every aspect of a transport ship is large and heavy, from the engines that power the ships to the loads they carry. The mobility and versatility of gantry cranes make them the perfect choice. The demands of shipyard applications require the use of a variety of heavy duty gantry cranes for ship building, repair, unloading, and material movement.
Warehouses
The versatility of gantry cranes is the main reason they are so useful in warehousing operations. Though it could be assumed that warehouses have the space for overhead cranes, in many cases, the structure of warehouse buildings cannot support them. Warehouses generally use an assortment of gantry cranes depending on the types of loads being stored. Normally, warehouse cranes are required to be mobile, so they can move extremely heavy loads from unloading to loading.
Construction
Another industry that relies on gantry cranes for their mobility and load capacity is construction. In the construction industry, crews move in to build a structure or building, then rapidly move out when the job is done. This type of instant in and out requires tools that can be used to fulfill the needs of the application but are capable of being torn down and removed. It is for these reasons that gantry cranes have become so important in the construction industry. The fact that a large, A frame gantry crane can be positioned and assembled for the work, then removed, makes them an ideal lifting solution.
The types of items that a gantry crane is required to lift for construction are concrete blocks, extremely heavy steel support girders, and loads of lumber. Regardless of the project, overhead gantry cranes for construction are heavy duty single or double girder designs.
Shipping Containers
Part of the supply chain is the movement of shipping containers that are the size of a semitrailer and exceptionally heavy and are transported by planes, trains, and ships. Unlike shipping containers of the past that could be moved by forklift, these huge, boxcar sized containers are moved, positioned, and loaded using mobile gantry cranes that efficiently lift them to be placed on trucks or trains.
The load capacity, mobility, and flexibility of gantry cranes have made them an ideal choice for shipping container movement. The ease and safety that a gantry crane offers enhance their function and smooths loading processes.
Gantry Crane Classifications
The classification of gantry cranes is to assist customers in the selection and installation of the right crane for an application. Proper selection ensures safe working conditions and longer working life of the crane. Pushing a gantry crane beyond what its classification allows can be dangerous, unproductive, and financially irresponsible.
There are multiple standards used to classify and rate cranes and their performance. The Crane Manufacturers Association of America (CMAA) has established classifications based on a crane‘s load intensity and number of lift cycles or how much weight a system will need to lift, how materials will be lifted, and how frequently it will lift.
Gantry Crane Classifications
A – Standby or Infrequent Service
Class A are systems used at slow speeds with long periods of idle time between lifts. This class includes applications for public utilities, motor rooms, and transformer stations. Class A gantry cranes provide precision handling of equipment.
B – Light Service
For class B, duty cycles and loads vary from no loads to occasional full loads of two to five lifts per hour with an average lift of ten feet. B class are found in assembly operations, repair shops, service buildings, and warehouses that require light loads to be moved at a slow speed.
C – Moderate Service
In the class C range, cranes handle loads averaging fifty per cent of their capacity with five to ten lifts per hour at a lifting height of 15 feet. The majority of cranes fall into a C class rating and include gantry cranes for manufacturing and machine shops.
D – Heavy Service
D class gantry cranes are in constant use with heavy workloads of ten to twenty lifts per hour at heights of fifteen feet. They operate quickly and are found where there is heavy equipment and materials that need to be continually moved and repositioned. This classification of crane can be found in foundries, fabricating industries, steel storage, train and shipyards for container movement, and lumber mills. Lifts are performed at 65 percent of the crane‘s capacity.
E – Severe Service
Class E cranes lift their full rated load capacity on an average of twenty times or more per hour with few limitations to their workload height. They operate at an exceptionally high rate of speed with motor stops of 600 per hour and a bearing life of 20,000 hours.
The Occupational Health and Safety Administration (OSHA) requires that severe service, Class E cranes, have frequent inspections that can be daily, monthly, or quarterly and have specific guidelines for the inspection process.
F – Continuous Severe Service
This classification of gantry cranes contains the most powerful types of gantry cranes—those required to handle full capacity loads continuously in the most severe and demanding conditions. Though class F is similar to class E, the difference between them is the demand of continuous operation for class F.
In the majority of cases, class F gantry cranes are custom designed to meet the needs of an application or facility and are built for optimum performance. To meet the predetermined specifications, F class cranes must meet frequency, use, and load requirements, which makes them difficult to design and fabricate.
Use Cycle
The use cycle of a gantry crane starts with the preparation for its first lift. The degree of utilization determines the use cycle and the level of classification of the crane. The factors that determine the use service life cycle include economic, technical, and environmental, each of which influence the age of the crane.
Conclusion
- A gantry crane is an overhead crane that features an overhead beam supported by freestanding legs, and it moves on wheels, a track, or rail system, carrying a bridge, trolley, and hoist.
- The lifting capacity of gantry cranes ranges from a few hundred pounds up to several hundred tons.
- Gantry cranes are designed in different styles with varying load and lifting capacities. Moreover, the range of shapes and sizes of gantry cranes makes them adaptable for any type of industrial use.
- Whether a gantry crane is small and mobile or huge and used in a shipyard, its components are divided into three categories: mechanical, structural, and electrical.
- The classification of gantry cranes is to assist customers in the selection and installation of the right crane for an application.
