Snap-ring pliers are a tool designed to install and remove snap rings, which are small metal rings that hold in a bearing or other assembly item by setting into a machined groove. Snap rings are common in car engine parts as well as in motorcycle and bicycle shocks and forks. While the snap-ring pliers are not a tool that will be used often, they are an important addition to a tool box because a snap ring is difficult or impossible to remove or install without them.
The tool itself looks like a regular set of pliers in a lot of ways. Snap-ring pliers have two arms that act as handles, and they are attached at a pivot point near the head of the tool. Snap-ring pliers have two arms at the tip: these small arms are bent at a ninety degree angle and each one features a small, round tip that will fit into the small, round holes on the snap ring. The snap-ring pliers are sometimes spring-loaded to aid in retracting the tool, and most snap-ring pliers feature a reversible head so the pliers can either pull on the snap ring in one position or push it outward in another position.
The snap ring is a circular metal ring that is broken at one point in the circle. At the break, two small circles are bored into the ends. This is where the snap-ring plier heads will grab onto the snap ring. Once the heads of the snap-ring plier are set into the snap ring holes, the user can squeeze the handles of the plier, which will in turn move the heads either inward or outward, depending on the position of the reversible head. To remove snap rings, the plier heads must move inward to make the snap ring diameter smaller. That way, the snap ring can be pulled out of the machined groove and free of the assembly.
To install a snap ring on the outside of an assembly rather than on the inside as described above, the head of the snap-ring plier must be reversed so the heads push the snap ring holes outward. This makes the diameter of the snap ring larger so it can be placed on the outside of an assembly. Once the snap ring is put into place, the handles of the plier can be released and the snap ring itself will relax into a smaller diameter, settling into the groove in which it should sit.