Horseshoe shims are used to pack between (say) the back of a panel and a restraint angle, or a restraint bracket and an insitu wall. They are an alternative to having a nut to maintain the gap between the panel & the bracket where there may be reversible loads, giving a ‘push-pull’ requirement.
They should only be used with tolerance-fit holes or slots. They should not be used to span across any oversized tolerance holes in plates etc, where plate washers are needed. They are designed to take the load from the setscrew/studding purely as a pack, and as such perform the same role as a bearing shim but in another direction.
The material should be the same as the bracket against which they are seated to avoid the risk of corrosion.
The example sizes shown here are typical only and different precast companies will have their own variations. The important factor is that the shim is stable when placed on the studding etc. If the legs are not long enough then there is an unacceptable risk of the shim turning upside down and falling off during installation or adjustment.
The slot width is ‘nominal bolt size + 2 mm’.
The thickness of horseshoe shims is similar to standard shim, typically 2, 3, 5, and 10mm. It is important that the gap is completely filled, with no spaces being left.