Designer's corner 23429

Belt drive

Large toothed belts stretch under load and rack-and-pinion drives need lubrication, but this linear drive is based on a small toothed belt having neither of these problems. The pretensioned belt is adjusted exactly to the toothed bar to reduce backlash to almost zero and provide a repetitive accuracy of 0.02 mm. Two auxiliary rollers press the belt onto the bar so that 15 to 20 teeth always engage the bar. In this system, the belt extension is independent of the bar length, making the effects of belt stretch practically negligible.

Zarian-Bewegungssysteme GmbH Meusselsdorfer ;Strasse 27, Marktredwitz, Germany, D-95615; Tel: +49 9231 603 836; Fax: +49 9231 8681.

Programmable encoder

Because conventional encoder assemblies require a specific disc for each number of incremental lines desired, only order-specific production is possible. This can result in long delivery times and large inventories.

Stegmann's CoreTech(TM)encoders, launched at Hannover Fair 2000, offer an electronic alternative. A common core, containing the disc and pickup electronics, is factory programmed to the required resolution. Assembly, therefore, is automated from a few stock components, and configured encoders (from 8,192 different line counts, and 32,768 absolute resolutions) are dispatched within 48 hours.

In addition, electronic zero adjustment eliminates mechanical calibration for quick and easy initialization.

Stegmann Inc. ;7496 Webster St., Box 13596, Dayton, OH 45413; (800) 811-9110; [email protected]