V-rings (also known as V-seals) are all-rubber seals that are installed directly onto a shaft to seal against a housing face, a bearing, or the back of a shaft seal. Offering simplicity and versatility, V-rings are chiefly used to protect bearings or other parts from contamination, as well as to retain grease. V-rings can also function effectively in dry applications with very low torque.

As shown in Figure 100, a V-ring consists of three parts: a body, a conical self-adjusting lip, and a hinge. In service, the elastic body of the seal rotates with the shaft while the adjustable lip maintains a dynamic seal in axial contact with a perpendicular counterface. The seal shown in Figure 100 is a “VA” style V-ring. VA style V-rings are the most common style and are used in appliances and conveyor rollers.

Widening the body of the VA style results in the “VS” style as shown in Figure 101. The expanded body and tapered heel of the VS style hold the V-ring in place on the shaft. VS style V-rings are used in agricultural and automotive applications.

V-rings offer many advantages. As shown in Figure 102, a V-ring tolerates greater radial variation (in this case, shaft cocking) than a traditional shaft seal. As shown in Figure 103, a V-ring also tolerates greater shaft-to-bore misalignment (STBM). A V-ring also tolerates greater dynamic run-out (DRO) than a standard shaft seal. And, as shown in Figure 104, a V-ring can function as both a seal and a slinger. V-rings are also less expensive than traditional shaft seals.

Another important advantage of the V-ring is its elasticity. A V-ring can be stretched during installation onto a shaft without disassembly of the unit, and one size V-ring can be used on a range of shaft sizes in either metric or English dimensions. A commonly used V-ring material is wear-resistant nitrile (-40° F to 225° F). V-rings made of fluoroelastomers are typical in applications with higher temperatures (-20° F to 300° F). As shown in Figure 105, V-rings are often used as supplemental seals in conjunction with traditional shaft seals. Studies have shown that a V-ring paired with a single lip shaft seal excludes contaminants better than a shaft seal with a conventional radial dirt lip.

Be aware that, because of their simplified design, V-rings are not intended to seal oils or other low viscosity fluids. V-rings are held in place by a hoop force generated when the rubber ring is installed on the shaft, but at high speeds, centrifugal force can cause the seal to lift off of the shaft. A garter spring or metal band can be employed to prevent this. Shaft motion can also cause the V-ring to slip axially on the shaft. A metal strap can be placed on the shaft to stop this.

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