How can nuts and bolts be kept from undoing during operation, so that the joint remains secure? This question became relevant from the very time the thread was invented. And the higher the speeds, the loads and the cost of mechanisms became, the more serious the problem of threaded joints «unscrewing themselves» became. Many locking methods have been invented: locknuts, split pins, Grover spring washers, drops of paint and so on. Each of these methods has its merits, but it also has drawbacks that sometimes make the use of one or another locking method impossible. Thus some methods require special nuts and bolts, others additional space, and others do not always reliably withstand vibration. The most modern and reliable method today is considered to be the use of liquid threadlockers: they provide reliable locking of the joint and at the same time do not have the drawbacks described above. What is more, using them is cheaper than practically all other methods.
Read more → Threadlockers. Which types exist and which to choose