AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

What Are Shear Pins?

Shear pins are small, yet critical components used in various mechanical systems as a failsafe mechanism. These pins are designed to break or shear off when a certain level of force is applied, thus protecting more expensive or critical components from damage. In this blog, we will discuss all there is to know about shear pins, including how they work, what causes them to break, how to identify broken shear pins, and how to replace them.

The basic principle behind shear pins is their ability to absorb and mitigate excessive force. When the force or torque within a mechanical system exceeds the shear strength of the pin, it breaks at a predetermined point. This function ensures that if the system experiences an overload or mechanical failure, the shear pin will break first to stop the transmission of force or motion, thereby preventing more significant and costly damage to other parts of the system. Moreover, shear pins are relatively easy and cheap to replace, ensuring that downtime is minimized.

As far as their construction goes, shear pins are typically cylindrical in shape, and they are often made from materials such as steel or brass. The diameter and length of shear pins varies depending on their specific application, but they are generally designed to fit snugly within a designated housing or coupling in machinery. Furthermore, the ends on some types of shear pins feature holes or grooves to accommodate securing mechanisms like cotter pins or bolts, ensuring they remain in place during operation. In all, the precise construction of a shear pin allows it to effectively serve its purpose as a mechanical fuse, breaking under specified conditions to protect the entire system.

There are a few factors that can cause a shear pin to break. As touched on, the most common cause is an overload condition, where the force or torque applied to the system exceeds the pin's shear strength. This can occur due to unexpected obstructions, mechanical failures, or operating conditions that are beyond the equipment's design limits. Wear and tear can also contribute to the weakening of a shear pin over time, making it more susceptible to breaking under standard operating conditions.

Knowing when a shear pin is broken is crucial for maintaining the functionality of equipment like snow blowers, marine engines, agricultural equipment, and various other types of machinery that utilize these components. One of the most apparent signs is a sudden halt in operation or a noticeable loss of power transmission in the system. For example, in a snowblower, a broken shear pin might result in the auger stopping while the engine continues to run. Visual inspection can also easily reveal a broken pin, as the pin will typically appear sheared off or misaligned within its housing.

Replacing a shear pin is generally straightforward and can be done with a few basic tools. The process typically involves either simply sliding out the shear pin or removing the broken pin with an appropriately-sized drift pin and hammer if it is stuck in place. Then, a new one can be inserted in its place from a shear pin kit. Alternatively, many systems have a shear pin lock mechanism that secures the pin in place. To replace a shear pin in a machine with such mechanisms, first locate the broken pin, then remove the cotter pins or similar fasteners that are holding it to slide out the broken pin. Finally, insert the new pin and secure it in position with the appropriate fasteners, being sure to verify that it is properly aligned and seated. It is imperative to ensure that any replacement pin matches the specifications of the original, including size and shear strength, to maintain the protective function of the machinery.

In conclusion, shear pins are indispensable components in many mechanical systems, providing a critical safety function by breaking under excessive force to protect more significant parts of the system. If you require shear pins or other essential parts for operations, we invite you to explore our selection on Stacked NSN. As an ASAP Semiconductor purchasing platform, customers can find over 2 billion high-quality product listings across this website, all being readily available for procurement. Take the time to explore our offerings, while noting that you are welcome to request quotes at any time with our online RFQ service and forms. To ensure a swift procurement process, our representatives are available around the clock and regularly offer tailored responses within 15 minutes of reviewing a submission. Bearing this in mind, get in touch with our team to see how we can help you secure all the components you need with time and cost savings.



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