In Bryce, has anyone ever tried to link a wheel to a piston, then the piston to a second wheel so that when the first wheel turns, the piston and the second wheel also turn? Can it even be done?

I suppose. Bryce does animation. You'd just have to set the motions of each object so they look like they're in sync. I'm no expert on animation, but it shouldn't be impossible.

I believe what he is talking about, is in the basic screen, with the mesh.  I do not believe it works that way.  If you linked them to a smaller control, just out of sight, and rotated that, it wouldn't work, for they would all rotate the same amount as the parent object.

I managed to animate 3 wheels and 3 pistons which all turn just by rotating the first wheel.  Is it possible to post my animation in here?  What format does it need to be in? anyone know?

you could post it on MySpace and post a link here, but there is also an animations freebies section that you could put the link in.

This one was done in Studio and assembled in Windows Movie Maker.

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=8846924

Well guess what!  I just put together a 5 wheel / 5 rod machine all rotating and sliding in sync just by turning the first wheel... But when I ran the animation everything started getting crazy, so I spent an hour trying to clear all keyframes to start fresh with my perfect first-frame setup, but it kept getting out of whack the moment I advanced the frames.  Why can't there be a 'CLEAR ALL KEYFRAMES AND START OVER' button?  Is that too much to ask for?  Anyway, I gave up this whole project in disgust... I already wasted too much time on it. 

Do a google search for 'Bryce Easter Eggs'. There should be a list of keyboard shortcuts that will be helpful for you.  They are not listed in the manual.  The list was made a while ago, but i think most of them still work.

I also believe there is a short tutorial about linking pistons and wheels.  Maybe at  DAZ.

There are many cool things that can be done with linking in Bryce.  You can also do searches for 'linking in bryce" or some variation.

Actually I succeeded in making quite an elaborate linked machine.... It's the animation keyframes that is the problem now.  I can't clear the old keyframes.  Even when I copy the whole machine to a fresh new file, the old ' motion paths ' stay with it and I cant get rid of them in order to start a new animation  run.

to clear all keyframes
stand on your head and while drinking a picture of beer upside down thru a straw, 
then hold shift/alt/ctrl and click on the "-" sign next to the key in the animation palette.  This will delete all keyframes in the current scene at one time.

There is no undo (as far as I know) for this tho..so use it only if you mean to.

:)
BT