The jam nut provides a quick and easy way to secure a subject nut in place or to secure a load. In this article, you’ll learn about its function and alternatives.
The width of a jam nut typically measures half as wide as a standard nut. It provides a locking mechanism by jamming against a standard nut and thus locking the two in place. Due to its small width, jam nuts may also be used in scenarios where a standard nut won’t fit.
Jam nuts may also be considered as such when they are providing a jamming function even when it has the same width as the subject nut. Jam nuts also see use when applied to threaded rods. Threaded rods do not have bolt heads, thus jam nuts provide the ability to put torque onto the rod. Users may use jam nuts to secure another nut, but also at times to tighten another object entirely.
Generally speaking, jam nuts are not considered best practice in industrial applications. Predicting the loads under stress is diffficult. Attempting to determine the yield or weak point in a connection becomes a function of torque imposed upon the connection. An effective long-term installation relies on skill of the operator. Jam nuts provide poor protection against vibration, thus requiring frequent inspection and maintenenance.
Adhesives may further secure jam nuts or provide an alternative entirely. When securing a load, industrial specifications typically call for lock washers in lieu of jam nuts. Conventional spring lock washers twist and flatten when compressed. This action reduces the spring rate of the bolted joint, allowing more force under the same vibration levels while also preventing loosening. Depending on the application and the materials involved, other types of washers such as the tab, tooth, wave, and Belleville provide reliable locking provisions.