ThePipingMart Blog Fasteners What is Jam Nut? Dimensions, Properties and Uses

What is Jam Nut? Dimensions, Properties and Uses

Jam Nut

Jam nuts may seem like a simple and small component in a fastening system, but they play a crucial role in maintaining the joint’s stability. They are a type of locknut with a thinner profile than a standard nut and are used to secure a bolt or stud. This blog post will discuss the dimensions, properties, and various uses of jam nuts in different applications.

What is Jam Nut?

A Jam nut is a low-profile locknut, typically half the height of a standard nut. It can be used as a locking mechanism to secure an assembly when tightened against another nut. Jam nuts are often used when a standard nut would not fit, or space is limited. They are especially helpful when working with mechanical parts and assemblies that require frequent adjustments, such as adjustable handles and levers. In addition to providing secure locking power, jam nuts provide vibration resistance due to their compressed design.

Dimensions of Jam Nuts

Jam nuts are available in sizes ranging from #0 to 2 inches in diameter and M1.6 to M52 in metric sizing. The thickness of a jam nut is usually half or less than a standard nut’s. The nut’s height is also smaller than a regular nut, allowing a bolt or stud to sit deeper into the nut. The standard thread pitch for jam nuts is the same as that of a bolt or stud.

Properties of Jam Nuts

Jam nuts prevent a bolt or stud from loosening due to vibration or thermal expansion. They provide an additional locking force that prevents the nut from rotating. Jam nuts create a jammed condition prohibiting the first nut from unscrewing or rotating. They are commonly made of strong materials such as stainless steel, carbon steel, zinc-plated steel, and brass.

Uses of Jam Nuts

Jam nuts are used in various applications, from household appliances to industrial machinery, where vibration is a concern. Common applications include vehicles, motorcycles, aircraft, bicycles, and construction equipment. They are also used in electrical connections, where a secure joint is needed to prevent arcing, short circuits, or corrosion.

Benefits of Jam Nuts

Jam nuts offer several advantages over conventional nuts, including improved joint stability, reduced risk of nut loosening, and better tension distribution. They also require less torque to achieve the same locking effect as a standard nut. Jam nuts are easy to install and remove, making them a popular temporary fix.

Installation of Jam Nuts

The installation of jam nuts is similar to other types of nuts. Place the jam nut on the bolt or stud and tighten it to its recommended torque value. Next, add a standard nut and tighten it to its recommended torque. Finally, loosen the jam nut and rotate it until it is against the standard nut. Tighten the jam nut against the standard nut until the locking force is achieved.


Jam nuts are a cost-effective and reliable way to secure bolts or studs in place and prevent them from rotating due to vibration or thermal expansion. They are used in various applications where joint stability is critical, including vehicles, industrial machinery, and electrical connections. Knowing the dimensions, properties, and installation process of jam nuts can help ensure a proper and secure fit for any application. If you need to improve the stability of your fastening system, consider using jam nuts.

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