On an elementary level, a slip ring is made up of two main components – a metal ring and a brush contact. With low speeds of 150 RPM or less it makes no difference if the rings rotate and the brushes are stationary or if the brushes rotate and the rings remain stationary. The number of rings and brushes found in a slip ring assembly vary depending on the needs of the device. Additional combinations of rings and brushes are stacked along the shaft or axis of the slip ring. Many slip rings are contained within housings to protect them from dust, moisture and other elements that may cause it to malfunction.
UEA brush contacts, which are always in pairs, are made of sintered metal copper graphite or silver graphite and rub against the outside of the rotating metal ring. They maintain a continuous electrical connection as one portion of the assembly rotates. The brushes are riveted to nylon arms and allowed to pivot at the rivet. The brush arms will also pivot on the brush posts. With both the brushes and arms allowed to rotate, complete contact at all times between the ring and brushes is assured. Although typically one brush pair per ring, amperage requirements may necessitate the use of four or even more pairs per circuit.
The ring is made of electrically conductive metal, usually brass, but it can also be plated silver or coin silver, and is usually mounted on, but insulated from, a center shaft. The insulating material between the rings and between the ring and the shaft is made of nylon, phenolic plastic or another non-conductive material. As the ring turns, the electric current is conducted through the brush to the ring making connection.
The wire leads from the brushes and from the rings are connected to electrical circuits. This is how a slip ring works.