The question regards my trailer, but it probably takes a pretty generic answer.
I've rebuilt my leaf springs. They need to be re-attached to the axle with the square U-Bolts. When the trailer was built in 1986, the U-Bolts were secured with lock washers. I don't like them. In this application, I don't much care for Nylocks, either.
I'm inclined to replace the lock washers with flat washers and secure the nuts with blue Loctite.
What say the hive mind?
Lock washers come in different styles, some when installed look just like plain washers. Find a style you like. There are self-locking nuts that aren't Nylocks also. Personally I would use one of these rather than relying on Loctite. But that is the aircraft tech in me speaking.
Most of the varieties of loctite should be fine, but check the loctite site to make sure the one you pick will hold up to the water and chemicals.
Another option would be to use jam nuts to make sure they don't back off, but can still be disassembled.
If you don't plan on taking them apart any time soon you could take a small punch and stake the threads. They could still be disassembled, but would take some leverage.
EvanR wrote: When the trailer was built in 1986, the U-Bolts were secured with lock washers. I don't like them.
Did the originals ever loosen up or fail? I mean just because you don't like lock washers doesn't mean they don't work. Sounds like they worked fine for the last 28 years.
WilberM3 wrote: nordlock locking washers? theyre called wedge lock at mcmaster
very fancy!
http://en.wikipedia.org/wiki/Distorted_thread_locknut
EvanR wrote:WilberM3 wrote: nordlock locking washers? Fancy, yes, but they work. theyre called wedge lock at mcmastervery fancy!
I don't know how often you rebuild leaf springs, but I would use red Loktite and put la prick punch on the bolt thread near the nut.
This won't be a problem next time because replacing the rusty U-Bolts just adds to piece of mind.
Dan
If you have enough thread, how about a second nut as a jam nut? Then punch the threads as 914driver describes and you should be solid.
Yeah, no to the split washers, those things are dangerous. Flat washers and proper torque for me. Nordlocks if you're paranoid, but they are pricey. Nothing else makes much sense to me.
What's your problem with Nylocks? I'd think that would be the perfect spot for them.
Streetwiseguy wrote: What's your problem with Nylocks? I'd think that would be the perfect spot for them.
me?
Nylocks are great for fasteners which are important to stay on and subject to small vibrations. Especially if they are not properly torqued. Small machine screws and such. In this application, it's pretty important that this bolt retains the torque load (really, the U bolt stretch) to be effective. Nylocks won't prevent a loss of loading, they'll just make sure the nut doesn't fall all of the way off. They are trying to solve a problem of the loose-ish nut leaving the bolt. If the U bolt gets to that point, you crashed a while ago.
Same with wirenuts, tabs, etc. They are great for preventing a loss of fastener, and in some cases, that's really important.
It's not like this is an area of large vibration, it's on a spring/damper after all. Torque them properly and leave it. Loctite if you want to be absolutely sure. Anything else is introducing an additional failure point.
You also could safety wire them.
I hate split lock washers unless they are GRADE 8 split lock washers.
That said, leaf spring nuts are not something that is torqued so loose that they need lock washers. Regular washers and zip 'em down and don't worry too much about it.
Kenny_McCormic wrote: You also could safety wire them.
See above, it doesn't do anything for torque. Clamping load will change.
In reply to tuna55:
OP, actually. I agree that a properly torqued nut doesn't require any additional foolishness- How often do you see lock washers on head bolts?
I was just curious what he didn't like about nyolcks.
tuna55 wrote:Kenny_McCormic wrote: You also could safety wire them.See above, it doesn't do anything for torque. Clamping load will change.
How so? The torque is an indirect measurement of how stretched the bolt/compressed the assembly is. If the nut can't turn the stretch can't change unless you've put enough tensile stress on it that it yields, and the nut's job provided it is high enough grade the threads don't shear out beforehand, has nothing to do with that. Anything that will hold it from backing off will work, its not like a trailer axle vibrates a whole lot or experiences enough temperature shift for the nuts backing off to be much concern anyhow.
Kenny_McCormic wrote:tuna55 wrote:How so? The torque is an indirect measurement of how stretched the bolt/compressed the assembly is. If the nut can't turn the stretch can't change unless you've put enough tensile stress on it that it yields, and the nut's job provided it is high enough grade the threads don't shear out beforehand, has nothing to do with that. Anything that will hold it from backing off will work, its not like a trailer axle vibrates a whole lot or experiences enough temperature shift for the nuts backing off to be much concern anyhow.Kenny_McCormic wrote: You also could safety wire them.See above, it doesn't do anything for torque. Clamping load will change.
The Nordlok guys do a great demo where they bolt a load cell with all of these forms of locking mechanism and measure the clamping load as it changes when mounted to a vibration table. The clamping load drops off, a ton. No worries, though, I don't think anything at all is required here other than flat washers and nuts.
Wonder what would happen if you used a split lock washer on top of a belleville washer, the belleville washer will apply spring tension to the lock washer which would maintain clamping force. Hell if I know though, I'm with the folks who say if it hasn't failed I'd just do it as the factory done.
In reply to tuna55:
This one? https://www.youtube.com/watch?v=mgwmuZuJ02I They seem to admit flat out that tabs, wire, and threadlocker, work, they're just selling ease of service. Kickass design though.
if you don't want to use what has already proven to work for 2 and a half decades, then just break out the welder and weld the nut to the bolt..
I went with the all-metal locknuts known as C-Lock nuts. My friendly, local, obscure hardware store had them on the shelf for $0.19 each in the 3/8"-16 size I needed. I added Loctite 242 for "suspenders and a belt" action.
tuna55 wrote: The Nordlok guys do a great demo where they bolt a load cell with all of these forms of locking mechanism and measure the clamping load as it changes when mounted to a vibration table. The clamping load drops off, a ton.
I can't wrap my head around this at all. The only way I can reconcile it with the way I think bolts work (they stretch and hold the parts together via tension, and this tension puts a lot of fricton against the threads so the nut doesn't loosen) is IF they used the same angle torque for the fastener instead of the same bolt tension. Nylocs DO require more torque for a given load because of the friction inherent to the design, just as much as the required torque is affected by what kind of lube (if any) is used on the threads.
In short, installation error, not a problem with the part.
Helicopters (a big vibrating platform) uses distorted thread locknuts on all dynamic components. So there must be something about that. In over 37 years of helicopter maintenance experience I've never seen one that was properly installed fail. Admittedly we do re-torque after a small amount of usage after initial installation. Mainly for settling. I've seen steel structure crack from the vibration load but the bolts and distorted thread nut stays torqued. In crashes that I've worked the investigation on, I've seen steel structure break apart and again the bolt/nuts are still together. If paranoid about fasteners then the only answer is to weld.
There are a few issues I see with that propaganda video on Nordlock. Don't doubt they work, I can see how they work but they downplayed some other important facts. One, they torqued the Nordlock more than the other fasteners so of course it will work a bit better. Two, they seem to use a bolt that had threads the length of the shaft. Been taught by engineers that will cause numerous issues. Smooth shank through the clamping area. Threads recess into a washer to keep the nut from bottoming out. Three, when they did the double-nut exhibition. The top lock nut didn't have full thread engagement, meaning it doesn't have equal loading and will back off. Not that I like this method anyway, just noting.
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