Huck lockbolts

[dozer]

Anybody out there ever use Huck lockbolts in a structure? I'm not sure if there are other brands. It's a pretty specialized fastener. Sees big use in the train car industry. Anyway, I'm looking for some guidance on safety factors for these things. We've always used the same SF's presribed for threaded fasteners.

 

[RHK]

As an aeronautical engineer, I regularly came across Huck Bolts, but have avoided them in civil structures. Huck Bolts are really just a rich man's rivet.

Apart from the expense, Huck Bolts are not really user-friendly for the riggers. There is no easy way to hold the joint while the bolts are installed - the first bolt pulled sets the joint orientation. If you need to re-plumb the structure, then start again with a fresh batch. With normal structural bolts, the rigger simply installs the nuts finger tight. He only goes back to tighten the bolts after he knows the whole frame is plumb.

There is a Huck Bolt suitable for blind fastening (where the rigger can't reach the back side of the joint). With structural bolts, the alternative of welding a nut on the inside has many potential pitfalls. I devised a "captive" nut system as an alternative to the welded nut, but found the market was limited. Has anyone else seen the need for an alternative to welded nuts?

Russell Keays