Rotary unions are highly versatile, space efficient devices which are used across many industries, although primarily in manufacturing. Its essential function is to transport a medium (gas, liquid) by connecting a stationary supply passage to a rotating part, e.g. tubing which connects to a rotating drum.
A simple but endlessly useful design, they have been utilised in agriculture, car washing, processing paper, plastic and foil into finished products, machine tools, mining, oil and gas, printing, rubber, steel, textiles and many more. Chances are there are many around your home.
They are typically comprised of four components: housing, shaft, bearing and mechanical seal. The housing, as the name suggests, houses the other three components. It may include an inlet port, an outlet port, remain stationary or rotate with the drum, depending on the scale of application.
The shaft carries the medium through the rotary union into the drum. Depending on the scale of application, the shaft may remain stationary or rotate with the drum.
The bearing, or bearings, come in many varieties but their function is to allow either the housing or the shaft to rotate.
The fourth and most important component is the mechanical seal which stops the medium from escaping the rotary union during operation. Seals come in a variety of types, and most rotary unions will employ more than one seal.
The rotary union, an unassuming but efficient piece of quality engineering.
Rotary Union Usage & The Process of how they are Manufactured