Mentioning all known securing system would result in a lengthy list, but the main principles for bolt securing are: Design the bolts with a large ratio between clamping length/diameter. The bolt will be rela­tively slim, making it more flexible and the surface contact under the head/nut will be maintained. Furthermore, the bolt has to rotate longer before the clamping force will be lost. This method is an expensive design - extensions and, of course, long bolts have to be used; Castle nuts, tab washers or locking wire secure the bolt. These securing systems involve relatively complicated assembly and disas­sembly. Unfortunately they cannot provide butt locking and part of the bolt force is lost; Increase of friction under the bolt head/nut or in the thread. Locking nuts increase the fric­tion in the thread and have the advantage that they cannot loosen completely by themselves. Unfortunately, the increase in friction is ineffective as long as the tension of the bolt is fairly high. Non-free-spinning threads make assembly laborious; Friction towards the material is increased by providing bolt heads/nuts with serrated surfaces, often in combination with a flange to increase the surface contact and the friction force.