As an alternative to split-pins or tab-washers, self-locking nuts prevent a joint from loosening usually by elastic deflection of part of the nut. These are also known as prevailing torque nuts, since the locking part of the nut grips the bolt/stud thread and a residual torque remains after the joint has been tightened.
Self-Locking Nut with Fibre Insert
These are fairly self-explanatory. A red fibre insert in the nut grips the bolt/stud thread. As a relatively soft material, the fibre renders the nut unfit for re-use.
Self-Locking Nut with Nylon Insert / Nyloc
This is the modern equivalent of the fibre insert nut, and are actually re-useable to some extent. However, for safety critical or highly stressed joints, new nuts should be employed. These nuts are not suitable for high temperature applications (above approx. 120 deg.C), where all-metal self-locking nuts should be fitted instead.
All-Metal Self-Locking Nuts
There is a bewildering range of nuts in this category due to many manufacturers coming up with their own designs. G.K.N. used to supply the fasteners for a great many British cars, and their Autolok nut was their answer to the self-locking problem. These are used extensively on the AC 2 Litre. but are no longer available.
Common (in the UK at least) alternatives are Binx, Aerotight, Phillidas and Cleveloc nuts.
<< Page 3 ****** Page 5 >>
Page 1 - Screw Threads
Page 2 - Bolts, Screws and Studs
Page 3 - Nuts
Page 5 - Washers
Page 6 - Materials and Strength Grades
Page 7 - Tightening
Page 8 - Wood Screws and Nails
Page 9 - Fasteners for the AC 2 Litre Saloon