L... Glossary of Fastener and Fixing Terminology







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A fastener having a square head, with a gimlet or cone point, and a thin, sharp, coarse-pitch thread, designed for insertion in wood or other resilient materials and producing its own mating thread, also known as a coach screw.  Product


A screw thread that is screwed in by rotating counter clockwise as opposed to the traditional right hand thread. Fun


The axial distance over which an external thread is in contact with an internal thread.


Fasteners used in steel construction that eliminate the need for drilling, welding and riveting  Product


Direct Tension Indicators (DTI's) is a term sometimes used to describe load indicating washers. Projections on the face of the washer (usually on the face abutting the bolt head or nut) that deform under loading as the bolt is tensioned. An indication of the tension in the bolt can be made by measuring the gap between the washer face and the nut or bolt head. The smaller the gap - the greater the tension in the bolt. Commonly used in civil rather than mechanical engineering applications.  Product


LockBolts consist of two parts: a pin, and a collar. The bolt is inserted into one side of the joint material and the collar is placed over the bolt from the other side of the joint material. Access to both sides of the joint is required. An installation tool is used to link the collar to the bolt providing a permanent and vibration resistant fastening.  Product

LOCK NUT          

There are a number of usage's of this term:  

The term is used for thin (or jam) nuts used to lock against a second nut. When used in this way the thin nut should be adjacent to the joint surface and tightened against the thick nut. If placed on top of the thick nut the thin nut would sustain loads it was not designed to sustain.

Lock nuts can also be applied to a nut which provides extra resistance to vibration loosening by either providing some form of prevailing torque, deforming or biting into mating parts when fully tightened; prevailing Torque nuts are also referred to a LOCKING Nuts to differentiate between thin nuts.


A Belleville washer, also known as a coned-disc spring, conical spring washer, disc spring, or cupped spring washer, is a type of spring shaped like a washer. It has a frusto-conical shape which gives the washer a spring characteristic. The Belleville name comes from the inventor Julien Belleville who patented the design in France in 1867  Product


Washers can be produced with a number of locking elements, serrated locking has been taken to a high level of sophistication.  Products


A hardened coil wire having a slightly trapezoidal section after forming which functions as a spring take-up device to compensate for developed looseness and the loss of tension between the parts of an assembly and to prevent the nut from turning.  

A split type of spring washer whose purpose is to prevent self loosening of the nut or the bolt. The idea or principle behind the helical spring washer is for one end of the tang of the washer to indent into the fastener (the nut or bolt head) and the other into the joint surface so that any loosening rotation is prevented. Junker in his paper in 1969 on the cause of self-loosening of fasteners concluded that this type of lock washer has limited ability to lock. This type of washer is sometimes called a spring washer. spring lock washer or sometimes a split lock washer. Product 


Are available as a shakepoof washers or fan disc washers both internally and externally toothed.  Fan Disc   Shakeproof




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