I have a mechanism which has several crank shafts, connection rods pulleys and fly wheels. Now for a feasability study, the pulleys and fly wheels are mated with concentic mates to the shafts, and with either planar mates or offset distance mates to their shafts (or the middle plane of the assy). When I supress the fly wheels and pulleys, the simulation runs well (I'm using the Adams solver in Motion).

When I unsupress these parts, they either move along their shafts as if the distance/planar mates would not be considered, or the entire assembly starts to wobble in space and everything seems to explode.

Now after wasting about two days on this, I found that when I replace the concentric + planar mates with hinge mates, things seem to work out again. Problem is, it's a PITA to create edges or faces on the shafts in order to mate the pulleys at the proper position for their axial location, at least for such a feasability study where the exact positions and dimensions are unknown.

What am I missing when I use the concentric + planar / offset distance mates to constrain the pulleys onto the shafts?

Thanks much, Frank

PS: Sorry if I don't use the proper terminology - using the German localized SolidWorks 2010 SP 2.1 x64