The locknut is also known as a self-locking nut which prevents the loosening action of the nut under high torque and vibration. During the process, some portion of the lock nuts get elastically deforms and gives locking action.
Why use Locknut?
Fastening of any equipment takes place with the help of a nut, bolt, and washer. But due to the high speed of the machines, it may cause vibration in that. Due to that, nuts start getting loose and may cause an accident. So lock nut is using to prevent it.
Types of Locknut
The lock nut is classified into Friction locknut, which works on the principle of friction, positive locking device, and locknut with integral locking.
- Friction Lock Nut
- Positive Locking Nut
- Industrial Locking Nut
Friction Lock Nut
It works on the principle of friction, where high friction between the lock nut and bolt causes the requirement of high torque for the initial few rotations during tightening and loosening. So like a regular nut and bolt, we can not tight and lose this friction locknut.
Nylon Lock Nut
In this nylon locknut, a nylon polymer collar has a diameter less than the outer thread diameter of the nut is inserted at extreme recess from the first contact recess of the nut. During the tightening process, this polymer deforms elastically and applies pressure. This pressure due to radial compressive force causes locking of nut. These nylon nuts work better up to 121 degrees celsius. More than this temperature lock nut cannot give locking action.
Distorted Thread Lock nut
This nut is shaped in such a way that, during mating with the shaft thread gets elastically deformed. It causes to increase in friction between them. Distorted threads are classified according to where the distorted thread is located, or its shape during distortion.
It is a half nut or low-profile nut commonly used with the primary nut to get a lock with it. It is used for such applications where a primary nut is not sufficient to prevent loosening action.
Enter Lock Nut – In this nut, distortion starts at the center to allow them to start from either side.
Top Lock Nut – In the top locknut, distortion of thread starts from only one side.
Depitched nut– This type of thread is displaced axially.
Positive Locking nut
Positive action nuts are like regular nuts, which can be free to rotate during tightening and loosening. But, these nuts get locked in their place when some positive action is done, like inserting the pin in that. It helps to do assembly very fast and makes them secure.
The castellated nut is a positive locking nut that has slots or notches cut on one side. The outer profile of the slot is round in castellated nut. But in slotted nuts, the outer profile is not round. These both nuts come with a pin or cotter pin for locking purposes. This pin pass through the slot and shaft on which the nut is fixed.
Industrial Locking Nut
This locking nut is commonly used in industrial machines.
Lock Nut with Lock Washer
The lock washer is engaged with bolt or keyway of the shaft first. Once the nut is inserted, then the tab of the washer is bent in the slot provided on the nut for locking. It is an easy and reliable method to install and remove the nut. With the new locking device, we can use them for other applications.
Lock Nut with Locking clip
A separate locking clip is attached to the nut during fixing to get in the slot of the nut. It is an easy and reliable method to install and remove the nut. With the new locking device, we can use it for other applications.
Lock Nut with locking plate
Locking plates fix in a keyway in a shaft and attached with the nut from the side faces by two bolts with locking wire. A locking plate consists of a plate, two hexagonal head bolts with drilled heads, and a lock wire to secure it.
Lock nut with integral locking screw
This lock nut gets tight with threads of the shaft by tightening the grub screw present inside the lock nut. It is a reusable type of lock nut. By loosening the grub screw, we can remove the lock nut and use for other application.
Lock nut with integral locking device
The integral locking device present inside the lock nut is tightened by the grub screw over the threads of the shaft. It is a reusable type of lock nut. By loosening the grub screw, we can remove the lock nut and use for other application.