What is a hydraulic rotary union?

A hydraulic rotary union, also known as a hydraulic swivel or hydraulic rotary joint, is a mechanical device that allows the transfer of hydraulic fluid or other liquids from a stationary source to a rotating component, such as a rotating shaft or a machine part. It is used in various industrial applications where the need arises to transmit hydraulic power, cooling fluids, or other liquids while enabling rotation.

The primary function of a hydraulic rotary union is to provide a leak-free passage for fluids between the stationary and rotating parts of a system. This is achieved through a combination of seals, bearings, and a housing designed to contain the fluid and prevent leakage, even as the connected components rotate.

Hydraulic rotary unions are commonly used in applications such as:

Heavy Machinery: Construction equipment, cranes, excavators, and other heavy machinery often require hydraulic power for various functions. Hydraulic rotary unions enable the transfer of hydraulic fluid to rotating parts, allowing them to perform tasks efficiently.

Industrial Machinery: In manufacturing processes, machines with rotating components may require cooling fluids, lubricants, or hydraulic power. A hydraulic rotary union facilitates the transfer of these fluids to the rotating components.

Printing and Packaging: Printing presses and packaging machinery often have rotating cylinders that require ink, coatings, or other fluids. Hydraulic rotary unions ensure a continuous supply of these fluids while the machinery is in operation.

Wind Turbines: Hydraulic rotary unions are used in wind turbines to transmit hydraulic fluid for pitch control, braking systems, and other functions from the stationary base to the rotating blades or nacelle.

Machine Tools: Certain machine tools, such as rotary tables and indexing heads, require hydraulic power for precision movement. A hydraulic rotary union allows the transmission of power to these rotating components.

Marine Equipment: Shipboard equipment, such as cranes, winches, and swiveling machinery, often uses hydraulic rotary unions to enable fluid transfer while accommodating rotation.

Automotive Manufacturing: Automotive assembly lines may use hydraulic rotary unions to provide fluid or hydraulic power to rotating fixtures during the manufacturing process.

The design and construction of hydraulic rotary unions need to consider factors like fluid compatibility, pressure requirements, rotational speed, and the environment in which they will be used. Seals and bearings must be chosen carefully to ensure minimal friction, wear, and leakage over time. Proper maintenance and periodic inspection are essential to ensure the longevity and reliability of hydraulic rotary unions in industrial applications.