This might seem basic but here it goes. I always have installed the ball in this order top to bottom: Ball, hitch, lock washer, nut. Now I have been reading on the net in a few places that the best way is: Ball, lock washer, hitch, nut. The reason I ask is because a friend borrowed a hitch and ball and he put it together: Ball, lock washer, hitch, nut. In other words is the correct way to put the lock washer on top or bottom of the hitch? No way I have been doing it wrong all these years. I'm serious this is not a joke. Thank you.

 

Tow Ready 2 Inch Hitch Ball Review Video | etrailer.com

Steve

 

I can't believe he believes that myself.

 

Scott,

You know how this stuff goes. One person starts saying it and pretty soon one of the RV forums pick it up and all of sudden folks head off in a whole other direction for who knows why?

Steve

 

The design purpose of a lock washer is too bite into the nut and the other non moving surface to prevent rotation.

If it is between the hitch and the ball it is nothing more than a spacer.

 

I've always put the lock washer "under" the nut and never had one loosen when properly torqued.
That said, few specifications call for helical spring lock washers anymore for the reason illustrated.



Experience indicates they are fine in a hitch application though. If you're concerned about loosening use a nylock or deformed thread nut (but be careful in selection, some are not reusable). Or use a Nord-Lock washer, they definitely won't come loose.
They aren't cheap though, for a trailer ball thread size they are $6-$10 each, but they are reusable.

 

I'm going to just continue to use what the manufacturer send. I just haven't seen any problems with it.

Steve

 

Yup. That's what I've been doing for 41 years. I'm confident that if there were a serious issue I'd have found it by now, considering some of the places I've towed trailers.

 

Reese makes what they call their Interlock system. Basically the ball mount has a hex shape cast into it, and the ball has a hex cast into IT. The idea of the system is to only have to use one wrench to tighten the ball. You can see an example of the ball here:
Reese Towpower Interlock 2" Hitch Ball, Chrome: Exterior Car Accessories : Walmart.com

If the lock washer were placed immediately below the ball, the hex on the ball would sit too far off the ball mount to engage the hex on the ball mount, thus defeating the purpose of the entire system. I've always put the lock washer next to the nut, and have never had the ball loosen up.
Somebody just doesn't got no idee what they's talkin' bout.

 

Rover, I've always had issues with that test.

One example I saw used two plates that vibrate against each other... A dynamic load rarely ever seen in practice. Normally there is a driving piece and a driven piece. In the test used to make that chart there were two driving pieces.

 

If you're talking about the Nord-Lock judder test video they have on their web site, it's really not that unusual a condition in industry, but I do agree it is a condition not normally seen in the automotive world.
I use them on exhaust manifolds so that I can use a lot of Never-Seez on the fasteners without concern about them coming loose.

 

Helical spring washers do one thing fairly well, they keep the nut from backing up. Other than that they are a hindrance to the integrity of the fastener and you will never find them used in critically stressed applications. A 2 inch ball (or 2-5/16) on a 1" shank is not critically stressed. I typically use nylock nuts in places where many would use a helical washer. In critical applications (usually farm implements in my case) I use poly-locks, which have the pinched top thread -- usually stamped in three places.

 

lock nuts and lock washers serve two very different functions.

Lock nuts generally get used where the nut is not torqued against anything, but must hold a tolerance tighter than a cotter pin. Using a bolt as the fulcrum on a lever handle is one common instance.

helical washers hold more torque as a nut begins to back off... up until the nut comes loose from the spring, too. It is a bit of a misconception that they are supposed to bite into the nut to keep it from rotating. That's what star washers do. Without the spring washer, the nut holds no torque (clamping force) at all after a few degrees turn, and is free to vibrate off.

 

Lock washers and self-locking nuts serve the same purpose. The nuts just do a much better job.
Lock nut are, in fact, used to create clamping force in joints and are better at maintaining that clamping force than helical lock washers and in critical (non-rotating) bolted joints are the preferred locking mechanism.
A few examples
From the NavyFrom NASAThe real purpose of helical spring lock washers is to save money. They are cheaper than lock nuts.

boltscience.com is a good resource for accurate fastener tech.

 

I guess if you wanted to, a star lock could be used between the hitch and ball, but a 'standard' lock washer goes between the nut and the fixed surface - or if it doesn't, my years experience as a military mechanic, years of auto mechanics, then working on very large commercials turbines has gone to waste