Gleitkontakt

Gleitkontakt, or sliding contact, is a mechanical-electrical interface in which two conducting surfaces slide against each other while maintaining an electrical connection. This type of contact is used whenever electrical energy must be transferred between parts that move relative to one another, such as rotating shafts or moving arms.

In electrical engineering, sliding contacts are common in devices where stationary and rotating parts must exchange current. The most well-known arrangements involve carbon or metal brushes that press against a rotating conductor, such as a commutator or a slip ring. Carbon brushes are favored for their self-lubricating properties and ability to limit wear, while metal brushes offer lower resistance in some applications. The term is sometimes used interchangeably with Schleifkontakt in German texts, though Schleifkontakt can also refer to other sliding-contact pairs.

Materials and design considerations are critical for performance. Carbon/graphite is widely used for its lubricating properties and high wear resistance; copper alloys or bronze may be used where higher conductivity is required. Surface finish, contact force, speed, temperature, and environmental conditions influence contact resistance, wear rate, and the risk of arcing. Lubrication strategies or dry-running designs may be employed depending on the application. Proper alignment and regular maintenance are important to prevent uneven wear and electrical problems.

Applications include direct-current motors and generators with commutators, slip-ring arrangements for rotating power transfer, and certain rotary encoders or switches that rely on sliding electrical contacts. Disadvantages include wear, sparking at high currents, and maintenance needs; alternatives such as contactless sensors or bearingless systems may be preferred in some modern designs.