Not every workshop has space for a full-span overhead crane. Neither does every job. In such situations, where space is restricted, or when the lifting requirement is confined to a single work cell, the most common choices are a jib crane or a mobile gantry crane. The lifting requirements of both of these systems are the same – getting a load off the floor without the need for a forklift. However, they are best suited to different environments and choosing incorrectly could lead to either underused capacity, or a system incapable of handling the job requirements.
A jib crane is a wall, floor, or column mounted lifting device that can rotate within a certain arc of 180 or 360 degrees. A jib crane is a good choice when the load lifting requirement is the same and is located in a particular spot, for example loading a machine tool, stock placement at a workstation, or servicing a single production line. The jib crane is a fixed lifting device and thus can be designed according to the specific requirements of the task. Therefore, for lighter and smaller load tasks, a lighter capacity length short arm jib may be used, and for large and bulky loads a more robust column-mounted jib may be used. In addition, with a jib crane, it is important to have the structure checked before the placement is finalised to confirm if the floor or the structure can support the load and moment.
A mobile gantry crane has flexibility, but lacks precision. Being on castors makes these cranes mobile for use in different areas of a site or for one-off lifts. They can easily be used and transported for a project, then removed for a different project. This makes them ideal for small businesses that can’t afford to dedicate a space for a permanent installation. This crane can also be useful for sites where the need for a lifting device happens to be mobile, such as a maintenance bay, a fabrication shop with an ever-changing layout, or a business that is still evaluating the best placement for a permanent crane. This crane has a lower safe working load than a fixed jib crane, and can only be used on a level surface with a load-rated floor.
No matter your crane selection, the hoist underneath it is just as important. Like the crane, you must consider the hoist’s rating in regard to a duty cycle in addition to its capacity. A hoist rated for a light/infrequent duty will fail with heavy/frequent use, and running the hoist beyond its intended class shortens its life. Many hoists outline different classes of usage, and for this reason, it is imperative that you state not just the max weight, but the daily lifts you intend on doing/completing.
Whatever gets installed, it still needs to go through the usual inspection process. A jib crane or gantry system will need to be examined by a competent person at the right time interval and will need to be checked prior to every use by the operator. A mobile gantry that gets rolled to other departments also needs the same documentation as a wall-mounted crane. It is easy to disregard the mobile gantry because it looks less permanent, but the regulations do not differentiate between permanent and mobile equipment.
There is a lot of grief that can be avoided by making the right choice the first time. An undersized jib crane results in extensively moving loads a long distance by hand. An oversized mobile gantry can’t be manoeuvred to where it is needed. It is best to identify the actual requirements of the intended use each time rather than working backwards from a desired type of crane. A reputable supplier will ask about the requirements of the intended lift prior to giving the quote.