there is now a new section in the documentation for the universal joint (with a picture!). much of the description was taken from an email from Martin C. Martin. it's checked into CVS, but the updated docs is at http://q12.org/ode/ode-latest-userguide.html, as usual. Martin, can you give it the once-over to check it actually matches what you implemented? russ. -- Russell Smith http://www.q12.org