Do You Know The Type of Rotary Joint ?

What is a Rotary Joint?

In the industrial field and many precision equipment, there is a key component that, although not often seen by the public, silently plays an irreplaceable role, which is the rotary joint. As the name suggests, it is a sealed connection device that can transfer fluid media (such as liquids, gases, hot oil, or steam) between a rotating state and a stationary state. Simply put, it allows rotating components to stably receive media from pipelines that are "stationary" while still in motion, solving the core problem of dynamic sealing.

There are various ways to classify rotary joints, including media, number of channels, installation methods, etc. However, the most common classification is based on their internal structure and compensation methods. The following are the main types:

Single End Spring Type Rotary Joint

The single end spring rotary joint is a relatively simple structure with a wide range of applications. It relies on a single spring to provide uniform axial thrust, making the rotating sealing surface in close contact with the stationary sealing surface. It has a compact structure, low cost, and is suitable for medium low speed, medium low pressure, and relatively clean media, such as the transmission of cooling water and low-pressure air.

Double End Balanced Rotary Joint

Under harsh working conditions such as high pressure, high speed, or corrosive and easily crystallizable media, single end sealing may appear inadequate. Double end balanced rotary joints have emerged. It has two pairs of back-to-back sealing surfaces, forming an independent sealing chamber. Corrosion inhibitor or isolation liquid (usually at a pressure higher than the medium pressure) can be injected into the sealed chamber, which can effectively lubricate the sealing surface, reduce wear, and completely isolate the process medium, preventing it from leaking or coming into contact with the outside air. This design greatly improves the reliability and service life of the seal, and is commonly used for the transportation of hot oil or corrosive media in industries such as chemical and papermaking.

Hydraulic Rotary Joint

Specially designed for hydraulic systems, commonly used in central rotary joints of construction machinery. Its characteristic is that there are multiple independent sealed flow channels inside, which can simultaneously transmit multiple high-pressure hydraulic oils without interfering with each other. It can achieve reliable continuous rotation of the upper part of the equipment (such as the loading platform of an excavator), while continuously providing hydraulic power to the lower part (walking mechanism or front-end working device), making it the core hub of complex hydraulic systems.

High Speed Rotary Joint

Designed for high speed equipment such as certain textile machinery and high speed rollers. Its core lies in the use of lightweight design, highly balanced rotating components, as well as special sealing materials and lubrication cooling structures that can withstand high speed frictional heat. This high speed rotary joint is designed to maintain extremely low frictional torque and stable sealing performance at extremely high speeds.

Siphon Type Rotary Joint

This is a special function rotary joint that is often used in conjunction with steam heating rollers. It contains a fixed siphon tube inside. Its function is not only to introduce steam into the rotating roller, but more importantly, to efficiently discharge the condensed water inside the roller, ensuring uniform heating and high thermal efficiency of the roller. According to the different ways of condensate discharge, it can be divided into differential pressure siphon and pumping siphon.