Spontaneous unwinding of threaded joints entails the danger of premature failure of a wide variety of machines and mechanisms. Grover's puck effectively prevents this undesirable phenomenon, but it has its drawbacks. Firstly, this is an extra assembly unit, and secondly, they can simply be forgotten to be put in place during the next disassembly.
How to get by without a Grover puck
The old way is to screw on a lock nut, that is, another nut wrapped over the main one. This method is effective, but not always applicable, especially in cases where the weight of the machine or mechanism is important, for example, in aviation or space rocket technology.
In order to improve the operational quality of the products of almost all branches of engineering, they invented self-locking nuts, that is, those with which vibration and other mechanical vibrations are in no way.
There are several ways to achieve this result.
Different types of self-locking nuts
The first method to improve the stability of the threaded connection is to make the mounting parts so that the self-locking nuts experience elastic deformation on the turns when screwed on, which is ensured by the so-called "tightness", that is, a positive tolerance that provides increased friction during twisting.
Similar deformations can also be achieved with multi-step cutting of the nut and bolt. At each subsequent turn, this difference will increase the force required to disassemble the assembly, which will exclude arbitrary self-loosening.
There is also a self-locking nut with a nylon ring, by means of which mechanical braking of any of their movements is carried out after screwing. The elastic polymer insert also plays the role of an additional damper, that is, a damper for mechanical vibrations, which also positively affects the reliability of the threaded connection.
A means of solving the problem is also a thickening in the lower part with a special notch that creates increased friction after it is pressed against the surface of the fixed part. These self-locking nuts are easy to recognize, they differ significantly in appearance from their regular hexagonal counterparts.
Original solutions
There are other ways to prevent unwanted and untimely unscrewing. For joints that do not experience significant mechanical loads during operation, self-locking nuts stamped from sheet steel can be used, which create increased resistance during the reverse stroke due to the springy properties of the material of manufacture.
It is also possible to use additional toothed rims fixed at the bottom of the fastener. Intensifying friction at the contact points, the protrusions reliably fix its position.
Despite the variety of shapes, any fastener is made in accordance with national and international standards, including a self-locking nut. GOST 5915-70 and DIN 985 are documents that regulate their size (and they come with metric and inch threads) and material (ordinary steel, alloy steel or stainless steel).