Lifting beams, spreaders and frames can be designed for general purpose or as bespoke beams for a specific use with a planned range of lifts.
Lifting beams, etc. are used for a variety of purposes which can include:
Stability is a key factor in the planning stages. In most cases using a lifting beam instead of long slings can reduce the overall stability of the lift. If the lifting points are below the centre of gravity particular attention should be paid.
To combat instability and achieve a stable configuration the height of the lifting triangle should be increased in relation to the loading triangle, so A should be greater than B, and D must be equal to or greater than C.
The weight of the lifting beam, spreader or frame, together with its associated lifting accessories, must be added to the weight of the load when assessing the total load imposed on the crane hook.
Many lifting beams and spreaders are fitted with standard lifting accessories such as shackles, wire rope slings, chain slings, web slings and plate clamps, turnbuckles, etc. The requirements of the individual sections of those code apply whether these items are readily removable from the beam or not. Whilst removable lifting accessories can be used for separate lifting applications, it’s good practice to keep them together as if forming an integral part of the lifting beam.
This is particularly the case if they are recorded with the beam on the EC Declaration of Conformity, report of thorough examination, etc. In the case of lifting accessories used separately, the onus is on the user to replace or reassemble these onto the beam. Care should also be taken to ensure that the component has in face been thoroughly examined in accordance with current legal requirements before using it for a different lifting application.
In addition to thorough examination necessary under statutory provisions, all lifting beams should be visually inspected by a Responsible Person prior to use on a regular basis. The interval between inspections will depend on the conditions of service. If any of the following defects are presents the should withdrawn from service and referred to a competent person i.e. a Hoist UK lifting engineer:
A simple lifting beam typically has a single lifting eye above the beam which is hooked to the lifting equipment and lower lifting eyes on the underside of the beam are used to connect the load.
The suspension points in figures 1 to 4 are shown as being vertically below the crane hook, although single suspension points are shown, multiple suspension point for use with two or more crane hooks are also available as are multiple load attachment points.
A spreader, also known as a spread beam as shown in figure 5 can be considered a strut in pure compression and the line of action of the top of the sling and the load suspension point coincide at the neutral axis at the end of the spreader.
A simple spreader will have a configuration made up of a suspension sling which the lifting equipment hooks onto at each end of the spreader beam, which are then connected to the load.
A lifting frame like that diagrammatically represented in figure 6 is in effect a combination of four spreaders.
You can have a combination of a beam and a spreader, a simpler example of this is shown in figure 7.