Sensors & Potentiometers

Potentiometers and other sliding position sensors are electromechanical devices whose performance and operating life can be dramatically improved through lubrication. Each of these devices has a metal wiper that moves along a resistive element, to regulate current flow to a device or to indicate when precalibrated positions are reached. The tracks may be any of a variety of conductive materials: wound metal wire, conductive plastic or ceramic compositions. Lubricating these tracks helps prevent wear, attenuate electrical noise and extend operating life.

Selecting lubricants for potentiometers & other electromechanical sensors oil or grease.

Wear prevention is the primary reason for potentiometer track lubrication. Most importantly, the lubricant film must be strong enough to prevent wear but thin enough throughout the operating range to prevent contact hydroplaning and resulting intermittencies. When working with small, delicate mechanisms with extremely low starting torque, oils may be required. However, greases, with their important stay-in-place advantage, have been the most successful potentiometer lubricants. Light, low shear greases, some approaching a semi-fluid state, can often be designed for even very low power applications.

Broad temperature film strength.

Since it is the film of lubricant that prevents wear, good film strength is essential. While arcing is not usually a problem, high heat generated by resistance — the temperature can reach 225°C in automotive dimmer switches, for example — requires a lubricant to retain film strength over a broad temperature range.

Ambient conditions also affect lubricant selection. Very low temperatures cause some lubricants to become so viscous that they prevent motion. On the other hand, in underhood applications where performance-related devices are multiplying, extreme wide temperature and fuel-resistant lubricants have become a necessity.

A note about damping greases.

Although not intended as track lubricants, Nye’s damping greases are widely used on potentiometers and other rotary devices where shaft/bearing lubrication is needed to damp free motion and produce a “velvet feel.” See our application summary on Damping Greases for details.