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How do Locking Nuts work?

Lock-nuts have a locking ability to resist loosening caused by pressure, force, and vibration. A free-spinning nut works to prevent vertical movement with the help of force that only serves for holding the fasteners. Unlike ordinary nuts, lock-nuts are distorted elastic and metal materials that are used to tighten components to protect them against vibration and torque. The uses of lock-nuts may vary according to the elements that need to get fastened. In this blog, we will take a brief look at the most common types of lock-nuts.

Friction Lock-nuts

The friction of lock-nuts used to prevent components from loosening or tightening requires a lot of force, especially in the initial rotation before restraint. The lock-nut design is hollow and flanged, and they do not spin freely nor need much time for application. They are also known as prevailing-torque nuts as they resist rotation while being connected or removed. There are different types of friction lock-nuts (also known as self-locking nuts), like:

Nylon lock-nuts – Nylon lock-nuts are also known as elastic stop nuts, and they are very effective. Nylon instilled in the nuts serves as the ‘collar,’ and its diameter is smaller than the threaded diameter of a nut. If the bolt is screwed, the collar will shift toward the threaded diameter and create friction that will lock the nylon nut in a stable position. Nylon nuts do not work appropriately in higher temperatures, especially those that are more than 120 degrees Celsius. These nuts are applicable in elevators, furniture, streetlights, lifts, and pipelines.

Self-locking nylon flanged hex nut – You can use nylon hex nuts with metal bolts for a number of applications. The flange is installed in the nut and works as a stable washer, allowing the force to act on the nut head so that it is spread across a large area. This will result in lower surface pressure which will not damage the surface and secure it in a constant place to avoid loosening. These nuts are popular and do not require a separate washer. You can use these nuts in electrical devices, construction, or metalworking.

Jam nuts – a jam nut's primary role is to tighten with another nut, as its name says. The jam nut itself is not a lock-nut, instead functioning alongside another nut to serve as a lock-nut. Jam nuts should be fastened before the primary nuts that are thicker and fitted at the top. With such an assembly, two nuts are fastened against each other, can bear pressure in the opposite direction, and are tightened in a constant place. You can use jam nuts in vehicles, furniture, pipelines, aircraft, and trains.

Stover nuts – Stover nuts feature a conical top and flat bottom with chamfered nuts, and the conical shape allows for auto-orientation while assembling, making such options more popular in high-volume applications. However, they do not have flanges that provide secure holds. Although they are called lock-nuts, they do not lock permanently, which means you can adjust or use them again. Torque nuts can be used as stover nuts specifically as well.

Positive Locking Nuts

Positive locking nuts are locks that rotate very quickly while tightening or loosening and can be assembled quite fast. Such nuts are rapidly fastened in position through an easy action. Some lock-nuts need a pin to be inserted, and others have a crown shape that is tilted inward while gripping. These lock-nuts are pretty expensive as they are fast assembled and more secure. A popular type of positive locking nut is known as the castle nut.

Castle nut – A castle nut works with pre-drilled bolts, with one end having notches. Castle nuts are best when there is a low force and no specific preload is required. If you do not have a cotter pin, use a safety lock wire or an R-Clip. Castle nuts are applicable to use in aircraft, automobiles, and trains.

Lock Washer Vs. Lock-nut

The lock washer can take on the torque down pressure of a bolt or screw. Yet, nylon nuts are best for durability and grip in terms of the tightness of joints. Nylon nuts can be bulky while working in compact spaces, whereas a lock washer is preferable in such areas. All types of lock-nuts have smooth ends with a round shape. The top of the self-locking nut is raised, while the bottom is a flat end that goes through the bolt first.

How To Tighten a Lock-Nut?

The process of tightening a lock-nut is quite simple. If you have a lock-nut, place it in front of the threaded bolt. Tighten the lock-nut with the help of your hand or any tool. Make sure the bottom of the nut sits against a surface. You can use a wrenching torque to tighten the lock-nuts until they reach the torque specifically required.

How To Measure a Nut Size?

It would be best if you matched a nut to a bolt before measuring the size of nuts. However, you can measure the diameter with the help of measuring tape from one side of the inner threads to another side of the internal lines. If you want to measure fine lines, use a magnifying glass to count the number of threads inside the nut and write it down to find out the threads per inch.

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