Alloy Bow Shackle with Screw Pin

Working load limits

In terms of correct specification of shackles, there are three main decisions to be made: the SWL, the shape, and the pin type. The working load limit must be at least equal to the total load imposed upon the shackle. If the load on the pin is distributed over its length, or part of its length, the load bearing capacity of the pin is effectively increased but that of the body is not. It should be stressed that distributing the load right across the pin does not increase the strength of the shackle.

Body shapes

Selection of the right body shape depends on the intended use. It is desirable to use a shackle with as small a jaw opening as is consistent with adequate articulation of the connection. Buyers can select from large and small dee and bow shackles, obviously providing a choice in terms of the size of the internal clearances. However, size for size, the smaller option has a higher SWL. Dee shackles are generally used to join two pieces of lifting equipment, while bow shackles are typically employed where more than one attachment has to be made to the body, for example if joining two single leg slings and connecting to the hook of a crane, or to allow freedom of movement in the plane of the bow. The necessity for the eye of a shackle to pass through another fitting may have to be considered.

Pin types

For dee and bow type shackles there are essentially only two types of pin available: the screwed pin type and the nut and bolt type. The screwed pin is suitable for most purposes provided there is little risk of the pin becoming unscrewed during the lifting operation. It has the advantage of keeping the shackle as a quick-to-assemble, two component item. The nut and bolt pin, together with a split retaining pin, is a four component item. The advantage of the latter, however, is that the pin cannot unscrew in service. It is therefore more suitable in applications where there may be movement which could cause the shackle to unscrew; where it remains connected for extensive periods; or in situations that do not allow the shackle to be seen easily and checked for security.

Working load limits

In terms of correct specification of shackles, there are three main decisions to be made: the SWL, the shape, and the pin type. The working load limit must be at least equal to the total load imposed upon the shackle. If the load on the pin is distributed over its length, or part of its length, the load bearing capacity of the pin is effectively increased but that of the body is not. It should be stressed that distributing the load right across the pin does not increase the strength of the shackle.

Body shapes

Selection of the right body shape depends on the intended use. It is desirable to use a shackle with as small a jaw opening as is consistent with adequate articulation of the connection. Buyers can select from large and small dee and bow shackles, obviously providing a choice in terms of the size of the internal clearances. However, size for size, the smaller option has a higher SWL. Dee shackles are generally used to join two pieces of lifting equipment, while bow shackles are typically employed where more than one attachment has to be made to the body, for example if joining two single leg slings and connecting to the hook of a crane, or to allow freedom of movement in the plane of the bow. The necessity for the eye of a shackle to pass through another fitting may have to be considered.

Pin types

For dee and bow type shackles there are essentially only two types of pin available: the screwed pin type and the nut and bolt type. The screwed pin is suitable for most purposes provided there is little risk of the pin becoming unscrewed during the lifting operation. It has the advantage of keeping the shackle as a quick-to-assemble, two component item. The nut and bolt pin, together with a split retaining pin, is a four component item. The advantage of the latter, however, is that the pin cannot unscrew in service. It is therefore more suitable in applications where there may be movement which could cause the shackle to unscrew; where it remains connected for extensive periods; or in situations that do not allow the shackle to be seen easily and checked for security"

Maintenance requirements are minimal. Keep shackles clean, the threads free of debris and protect from corrosion.

Regularly inspect shackles and, in the event of the following defects, refer the shackle to a Competent Person for thorough examination: illegible markings; distorted, worn, stretched or bent body; bent pin; damaged or incomplete thread forms; nicks, gouges, cracks or corrosion; incorrect pin; any other defect.

In the UK, the Lifting Operations & Lifting Equipment Regulations (LOLER) make it clear that all shackles and eye bolts used for lifting purposes are lifting accessories. They should therefore be subject to a thorough examination by a competent person at least every six months. Regardless of the prevailing legislation, the Lifting Equipment Engineers Association (LEEA) strongly recommends that this policy is adopted by all those with responsibility for ensuring the safe condition of lifting equipment.

If you are in any double please contact Ultimate Lifting Solutions to discuss your LOLER / Thorough Examination requirements, we have trained engineers that can carry out all your inspection / services either on-site or in-house