V-Ring Seal Sizing: Shaft Diameter, Profile and Installation Space

A V-ring inquiry should identify the shaft it will fit, the seal profile and the space available around the sealing face. A dimension copied from a loose rubber ring is not enough to select an installed seal. Separating these references makes it easier to compare a proposed part with the machine arrangement and ask useful questions before ordering.

This guide concerns the elastomeric shaft-mounted V-ring used for axial sealing. Include a section view when requesting it, because the term V-ring can also appear in descriptions of other sealing arrangements.

Separate shaft diameter from the uninstalled seal bore

A shaft-mounted V-ring is stretched onto the shaft. Its lip contacts a counterface perpendicular to the shaft, rather than sealing radially on the shaft surface. Manufacturer tables therefore distinguish the applicable shaft diameter range from the seal’s inside diameter in its free, uninstalled state.

Record the actual shaft diameter at the intended seating position, with units and the relevant tolerance. If you also measure a loose reference seal, label that measurement as the free-state bore. Keep the two values in separate fields. A proposed free-state bore should be checked against the manufacturer’s shaft range for that exact profile and size, not treated as the required shaft diameter.

Identify the profile and its reference

VA, VS and VL identify different V-ring profiles in SKF’s catalogue. VA has a standard section with a straight back face; VS has a wider body and tapered back face; VL has a compact axial section. These differences matter when describing the available space. A profile name alone still does not specify the complete part.

Supply the reference manufacturer’s designation, any legible marking and a section sketch. Ask the supplier to identify its proposed equivalent with a drawing or dimensional table. Do not assume that similar letters used by different suppliers establish an identical section, material or installed position. If the reference is uncertain, say so instead of selecting a profile from appearance alone.

Describe the installed space

Show the shaft seat, nearby shoulder and stationary counterface in the same view. Mark the axial space available for the seal and the distance used to locate it relative to the counterface. Include surrounding clearances and any support or locating feature. Keep the installed dimension separate from the width of a loose seal.

Describe expected shaft end movement and changes in the relative position of the shaft and counterface. Ask for the permissible installed position and movement for the proposed seal. An apparently suitable shaft range does not, by itself, confirm that the lip will work in the available axial space.

Include the counterface conditions

The counterface is part of the sealing arrangement. Provide its material, surface condition, finish specification and exposure to water, dirt or other contaminants. Record operating speed and whether the arrangement is lubricated. Manufacturer guidance connects counterface requirements with operating conditions, so one finish recommendation should not be transferred to every application.

Also identify shaft runout or alignment concerns and any sharp edges along the installation path. Provide observations or measured information where available. Request the appropriate preparation, support and installation instructions for the proposed design rather than improvising them from a photograph.

A useful inquiry package

• Actual shaft seating diameter, units and tolerance.
• Profile, reference designation and a section view.
• Free-state seal measurements, clearly labeled as reference measurements.
• Installed axial location, surrounding clearances and locating features.
• Counterface material, condition and finish requirement.
• Speed, movement, lubricant, contamination and material requirements.

If a V-ring will protect another seal, show both components in the installation sketch. For related radial sealing information, browse IKSONIC’s oil seal overview. Identify which component is being requested so that a related product family is not mistaken for an approved replacement.

Short FAQ

Can I order using only the loose ring’s inside diameter?

No. State the actual shaft diameter and confirm the applicable range for the proposed profile. Keep the loose measurement as separate reference information.

Does VA specify the material?

A profile label does not establish the complete material specification. List the required material or ask for a documented proposal based on the operating conditions.

Is a photograph enough to establish installation space?

Use photographs to support a dimensioned installation sketch. Ask the supplier to confirm the proposed installed position and relevant clearances.

Contact IKSONIC with the shaft information, profile reference and installation sketch you are authorized to share.