Motors often use encoders for position or speed feedback. Some devices, called multiturn encoders, track shaft position over several rotations and rely on a battery-powered counter to store this information.
The Acuro AD36 absolute encoder from Danaher Industrial Controls, Gurnee, Ill. (danaher.com), takes a different approach. Rotational information is coded in the position of several lowprofile gears. This eliminates batteries as source of maintenance and downtime. The nonmagnetic gears are also immune to interference from welding machines and motors with powerful brakes. The gears also save space, giving the unit an installation depth of 31 mm. The gears provide multiturn resolution up to 12 bits, and the entire device can run at up to 12,000 rpm.