Threaded fasteners like screws and bolts get loose from the part to which they are attached. The loosening can occur due to shocks, vibrations, and other types of forces. In such a case, a locking fastener can be useful as they are externally threaded like a screw or internally threaded like a nut.
Types of locking fasteners
There are two types of locking fasteners, which include free-running and prevailing torque. If a free-running fastener has to be used, then a washer or jam nut needs to be added. These washers may wear and tear with time and need to be replaced. The prevailing torque type fasteners develop friction. If there is a slight loosening, then further loosening can be restricted due to friction. Free running fasteners are of many types, which are discussed here.
Jam nuts are considered fasteners that were and are still used to resist the loosening of the nuts and bolts. To install jam nuts, first, they are tightened. The next step is to tighten the normal nut whose loosing is prevented by the jam nut. To provide extra resistance, a bolt has to be tightened to increase the resistance to loosening.
Slotted and Castle Nuts
These nuts can be used with bolts and a hole is to be drilled on the wall or the object in which it has to be fastened. After the installation of the nut, a cotter pin or safety wire is inserted from both sides to prevent from loosening. The position of the nut remains intact unless the wire or cotter pin is damaged. Tightening the nut completely may not be possible and it is also done to align the hole and the slot.
Lock washers are very popular fasteners, which are used with small nuts and bolts. There are two types of lock washers, which include spring action and tooth. To install the spring action washers, place them under the screw head and compress it while tightening. This will produce resistance to loosening of the nuts and screws. Tooth lock washers are inserted into the nail through their teeth and fasten it.
There are many disadvantages of using lock washers. The tooth lock washers can crack the surface in which they have been fastened. The conical washer should be installed correctly else it might not work effectively if restring the loosening. The spring type works only when the nut is slightly loosened.
Due to these disadvantages, the lockset washer pair is being used which consists of a top and a bottom washer. These washers can be installed in such a way that they interlock themselves. After, the screw and nuts are tightened and the toothed in the washer pair is fastened in the screw.
Locking fasteners are very useful as they prevent the loosening of nuts and screws. They should be properly installed so that they can function effectively in any condition.