On Thu, Mar 25, 2010 at 10:08 AM, Sean Breheny wrote: > We have a robotics application which puts fairly high reversing loads > on caster wheels. > We are looking for a source for heavy-duty casters > which are either conductive or dissipative (we can deal with roughly > anything from 0 ohms to 10^9 ohms from hub to floor) to counter some > ESD generation problems that we have. So the high reversing loads are causing the ESD (Van De Graaff between floor and cart)? Or are you merely trying to reduce ESD by using the wheels as the discharge path? If the first, then you might look into other wheel materials (and possibly floor coverings/coatings) to reduce the generation of the electrostatic energy. If the latter, I'm sure such wheels exist, but my understanding is that it's more common to have a dangling conductor (or sprung conductor) in constant contact with the floor. You have much greater control over the discharge resistance and path, and since the wheels don't "wipe" they can become less effective over time due to dirt, oil, etc coating them. A wiping ground contact can be made that will self clean, won't mar or mark the floor, won't catch on minor ground imperfections (cracks, concrete stress releif joints, etc), and will wear well. However, I think the search terms that you need are "condutive wheels" and "anti-static wheels" http://www.google.com/search?q=conductive+wheels http://www.google.com/search?q=antistatic+wheels And they appear to be widely used in, for instance, the medical industry. -- http://chiphacker.com/ - EE Q&A site -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist