Quick Nut Question

[Sonor]

No, hickory or walnut  but metal nuts. 

 

I have a John Deere lawn tractor that uses the nylon stop nuts for a variety of removalable pieces. How often should you replace these type of nuts? Can you get multiple uses out of them before replacement or are they use once and discard?

[MichiganBob]

 I found this on the Internet. Sounds about right.

 

"Are Lock Nuts Able to be Reused? ... They are able to be reused, but only if the prevailing torque meets certain specifications. Lock Nuts with a Nylon Insert are perhaps the most reliable lock nut, as it is only limited by the temperature of the application it has been used in."

[MichiganBob]

Also:

 

"Nylon Locking Nuts 

Nylon locking nuts are also very easy to install, but offer excellent resistance to loosening. Friction heats up and softens the nylon insert during installation, allowing it to be deformed by the thread of the screw. As this cools down, the nylon insert hardens, locking the fastener into position. A nylon locking nut is very difficult to remove after installation, but is vulnerable to high temperatures and certain chemicals.

Nylon locking nuts are in various materials such as stainless steel and aluminium and the nylon insert is available in different colours. They are available in the following variations: nylon dome locking nuts, high nylon locking nuts and flanged nylon locking nuts."

 

 

[TEWKS]

Without any scientific knowledge at my disposal I’m gonna toss out, “put a dab of Loctite on them” and tighten up. 

 

Now if a blade could possibly come loose and kill the neighbors pet…I didn’t recommend that…

[Skywagon]

I usually replace them with all metal lock nuts from Hillman or other brands

[Sonor]

Thanks all ...

[MichiganBob]

Let's go nuts. Different applications require different types of lock nuts. It's the same with bolts. For example, on my early Beemer models, you always replaced the driveshaft bolts when they were used once. If I recall, it was due to their losing their initial and desired strength once stretched. I would think that different components on my current ride require different levels of fasterners.

 

What are Lock Nuts?

A lock nut, also referred to as locknut, locking nut, and self-locking nut, is a kind of fastener that used to secure bolted joints and resist loosening under vibration and torque. After inserting a bolt through the objects, a lock nut can be twisted onto the end of the bolt (from the backside of the object), in conjunction with the bolt and secure the whole part. The lock nuts can prevent loosening either utilizing the friction or some positive locking device, depending on its structure and materials. The installation procedure is basically the same as normal nuts. 

How Does Lock Nuts Work?

Unlike traditional nuts only contains a basic threaded hole, the lock nut generally features a unique design that avoids the nut loosening from the bolt where they are placed when under vibrations. There are different varieties of locking nuts, such as the metal nut, employs metal to create friction, and the nylon insert lock nut, incorporate a polymer in the design against loosening. When a nylon lock nut is placed on a bolt, the nylon fibers expand to grip the bolt. The metal lock nuts work to secure the bolts in different ways. 

Different Types of Lock Nuts

The most common lock nuts types are metal lock nuts and nylon insert lock nuts. The metal lock nuts can be divided into more different varieties. Here we listed the common types of lock nuts with figures you can identify it more easily. 

1. Nylon insert lock nuts

This type of lock nuts have a layer of nylon insert inside of the nut, when you put the bolt through, it starts to thread the nylon, then it puts pressure on the screw and prevents it from vibrating loose and even falling off. The nylon insert nut features an internal nylon washer or patch, the addition of non-metal material makes the nut is more sensitive to temperature and chemicals. To install the nylon insert lock nuts, a tool is required. 

2. Hex jam nuts

The jam nut is usually used with another nut together, you should tighten them up against each other, that’s why they called jam nuts and how they work. They can also be used in a tight area where a full-sized nut can’t be completely placed. 

3. Prevailing torque locking nut (Stover lock nut)

It has a locking mechanism that’s built into the cone, as you put it on, it starts to act like a locking nut, its self-contained feature creates frictional interference between the threads of the mating components. When fastening a prevailing torque lock nut, there is a resistance to rotation during both assembly and disassembly requiring them to be wrenched; that resistance is called prevailing torque. They can be adjusted or removed after installation. 

4. Two-way lock nut (Center lock nut)

There is a small mark in the middle position on the outside of the nut, almost like a punch right in the center, that shows it’s a two-way nut, as the name suggests, this kind of nut is locking in two ways, whether you put it on or off, once you start to screw up to that size, it will start to lock. Both Stover lock nut and two-way lock nuts use distorted threads to keep the nuts from loosening. The difference is that the distorted thread of Stover nuts is at the top and two-way nuts have it located in the center. 

5. Serrated Flange lock nut

This lock nut has an integral flange built into it and the backside is serrated, typically used in applications where you have some type of metal sheeting or something that has metal. After you tighten it down, the serrations will prevent it from backing off. 

6. Keps K-Lock nut

K-Lock nuts have little wings around, which is movable, it’s a free-rolling washer lock nut, when the wings get tightened, note not to over tighten it, because once you over tighten the nut, it’s no longer a lock nut, and that free rolling washer gets crushed, it doesn’t work for you anymore.

7. Castle lock nut (Castellated nut)

Castle lock nuts are a type of nut with slots cut into one end, typically used in low-torque applications, such as holding a car wheel bearing in place, you can find them on axles when they hold on wheels and bearings.

[TEWKS]

Bob, that is,  just nuts! 

[Hosstage]

The most common lock nut I use is the cross-threaded standard nut. While not available from any manufacturers, I seem to end up with at least one for every project I do. And while not necessary, they are often paired together with the cross-threaded stud or bolt. The goal with those is one time use, but often end up being re-used after a quick thread chase, because I'll be damned if I can find a good replacement in the spare parts can....

[Lowndes]

6 hours ago, Sonor said:

 

I have a John Deere lawn tractor that uses the nylon stop nuts for a variety of removalable pieces. How often should you replace these type of nuts? Can you get multiple uses out of them before replacement or are they use once and discard?

 

Sonor,

 

I have those nyla nuts on my JD lawn mower, too.  And, bunch of other things, most recently the Zumo XT mount to a Ram ball adapter.  I don't pretend to count the reuses on any of them but would guess some would be 12-15 times, maybe more.  They still hold.  On your lawn mower if something falls off at least you aren't far from home.  With the Zumo it might be different (it's not mounted on my lawnmower).  

[Paul De]

Lock Nuts, isn't that the hazard from going commando and getting the tender bits pinched between your thigh and pants? 

[TEWKS]

1 hour ago, Paul De said:

Lock Nuts, isn't that the hazard from going commando and getting the tender bits pinched between your thigh and pants? 

75+ 

 

Years ago I was told a story (embellished IDK) about a medical call for this sickly old fella. Talk about “famous last words” as they were transferring him onto the stretcher he sat on his own nut sack.  (< that may not be a medical term anymore btw) They said the poor guy screamed out ”OUCH MY BALLS” right before going into cardiac arrest! I shouldn’t chuckle but, I think you’re good. 

[lkraus]

If you need a wrench to spin it down, vibration won't spin it off.

[roadscholar]

Vibration is likely what they’re for on a lawn tractor, might get away with re-using once or twice but not much more.

 

On air cooled 911’s in the 70’s the aluminum engines expanded and contracted greatly because EPA regs made them run very hot, sometimes 260-270* oil temps (75-77 being the worst years with thermal reactors). Nyloc nuts for the valve covers were only good once, excessive heat usually did them in. Parts suppliers included new ones in a valve cover gasket kit.

[Joe Frickin' Friday]

Good video of a vibration testing machine being used to test various types of bolted joints.  A nylock nut is tested at 2:14, and something more exotic is shown at 3:06.

 

 

 

 

[Paul De]

Never had a problem reusing a Nyloc nut numerous times.  I guess if it spun on without resistance I would replace it.  It should only need a little resistance, since if it backed off the bolt assembly would spin.  Might be a problem for applications where a water tight or oil seal is needed.   I think the  application for a nyloc but works best is where you don’t actually want to snug it down and sure beats messing around with a jam nut