What is a Rotary Union?

A rotary union or swivel joint is a mechanism used to transfer fluid (under pressure or vacuum) from a stationary inlet to a rotating outlet, preserving and isolating the fluid connection.

Also referred to as a rotary joint, rotary coupling, fluid swivel or swivel joint, rotary unions are engineered to endure a large range of temperature and pressure for a variety of conditions and environments.


In addition, rotary unions may integrate multiple independent flow connections (passages) and handle different types of media simultaneously.


Rotary unions typically function by connecting to an input and securing onto another mechanism while allowing a moving connection to be preserved. Rotary unions are utilized in a variety of applications; from compact rotary unions for the semiconductor industry to large, rugged-duty fluid swivels for industrial applications.


Additionally, a variety of materials, sealing technology, and bearing types can be incorporated.

Fluid Rotary Union Diagram

Example: Rotary Union Use in a Workholding Application

In the example below, a (3) passage rotary union transfers hydraulic fluid from (3) stationary hoses to supply the hydraulic powered clamps. The shaft of the rotating union is mounted to the rotating shaft of a rotary table. The rotary union allows a rotating connection to be preserved and isolated while transferring the media (hydraulic fluid).

Fluid Rotary Union Workholding Application Example Diagram

Additional Examples


More Information See More Examples of Rotary Unions