Prolyte Campus blog: Rigging and such: Orientation of Bow Shackles

Undoubtedly the most used item in rigging and probably also the most abused one. They come in Bow-type and in D-type of shape, the D-type is not so common in the entertainment industry, as it may not be used in any other than a straight in line pull and a bow shackle can do that anyway.
Short summary:   “D = NO”    “Bow = YES”  

When used for rigging purposes first of all make sure the equipment is load rated, secondly; know what the applied load will be. (Overloading of lifting equipment is forbidden in every country in the world).

Much can be said on the orientation of bow shackles, but the most important thing is the direction of the force(s). The bow is designed to absorb a bridle force, where the pin side only is to be loaded perpendicular to that pin. If the bridle apex point ends up in the bow, all is fine. As soon as any arrow is marked red the shackle use is wrong.  (See picture below in pos. 4 through 7)


 
So in straight pull only, the pulling parts shall be on the pin and the crown of the bow only. Still in straight pull the choice for the orientation is not completely free, it’s important to understand that the Centre of Gravity (CoG) in a shackle is always closer to the pin.
Therefore it is wise to have the pin side facing down and the bow facing up. This is how you can prevent that in a slack line situation, the shackle can turn itself (the heavy part facing downwards) ending up in a transverse load, shown above in pos. 6 and 7.  This is a simple but effective example of good rigging practice.
 

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From the first batch of truss we bought, we were totally convinced Prolyte was the right choice.

Richard Fiedler Owner Fiedler Veranstaltungstechnik