Although called a Jib Crane, it is actually a structure designed to support a manual or electric chain hoist. The type of jib crane or chain hoist you choose should be most suitable for your operation and the intended use, while a jib crane and chain hoist can be sourced from separate suppliers we recommend choosing a reputable vendor who can supply you with the full lifting solution to ensure you receive technically correct solution that is fit for purpose and a focus on safety.
Slewing Jib Cranes
A slewing jib crane compromises a horizontal runway track (the jib arm) cantilevered out from a vertical king post located in bearings. The king post and bearings allow the jib arm to slew and the lifting chain hoist is usually mounted onto a push travel trolley which travels along the jib arm.
The combination of slewing arm and trolley movement means that the chain hoist can placed to lift and move a load to virtually any position within the arc of the slew, allowing the load to be moved in all 3 planes.
Wall Mounted Jib Cranes
A wall mounted jib crane fixes the king post’s bearings to an existing structure i.e. a building, column or wall. If fixed to a wall, the jib crane would be limited to 180° of slew, however column mounted units could rotate up to 270° dependent on the installation.
During discussions with Hoist UK’s technical teams we will propose the most suitable
jib crane configuration for your operational requirements, supply drawings outlining the imposed loadings on the structure (wall/column) and calculate a ‘maximum moment’ in force, which is generated by the combined weight of the load and lifting appliance when at the end of the jib, whilst factoring in the dynamic effects of lilting and lowering the loads. These drawings should be verified by a structural engineer and approval communicated to Hoist UK prior to installation of a wall mounted jib crane.
Free-Standing Jib Cranes
A free-standing jib crane has its own specially designed column and when installed would be fixed to the ground. In order to fix a free standing jib crane to the floor foundations with considerable depths would be required in order to withstand the overturning moment. A tubular column allows for a full 360° slew but it’s important to note that if being used with an electric chain hoist the power supply has to be via slip rings, unless stops are incorporated to prevent a full rotation.
A low capacity, short radius jib crane would be fixed directly to the floor providing the floor specification is accurately known, is suitable and in good condition. For jib cranes with a larger radius and load capacity, the most cost-effective option for mounting would be to cast directly into the floor however, this would make moving it at a later date an unattractive proposition. The alternative that is often a more suitable installation is a bolted connection which requires a base plate and fixings requiring more space around the base of the column, or the use of chemical anchors.
Under-Braced and Over-Braced Jib Cranes
Under-braced and over-braced jib cranes are named for how the cantilevered arm is supported.
An over-braced jib has a tension member from the top of the king post to a point about two thirds of the way down the jib arm. The advantages of this are a lighter structure and one which allows the chain hoist to get as near as possible to the supporting structure giving the maximum effective travel. It also facilitates the use of special track sections instead of a rolled beam. The disadvantage is that more headroom is needed for a given height of lift. An under-braced jib has the cantilever support beneath the runway beam. This keeps the headroom required to the minimum but
necessitates a heavier rolled beam and reduces the maximum effective travel.
In most applications, the jib will be slewed and a push travel trolley will be used. Caution is advised, particularly if the jib is high-mounted as pushing on the load will cause it to swing away from the vertical centre line of the jib. The greater the distance between the load and the jib arm, the more accentuated the swing will become. Another option offering a more controlled movement would be a powered travel trolley, and there are options available that provide powered slewing for the free-standing 360° style of jib crane.
