I'm using SW 2009 to create a compound gear train assembly. Each gear is mated to its shaft, which together, forms a subassembly. In some subassemblies, gears are compounded together, i.e. one shaft can share 2 gears colinearly, for instance. So the first subassembly will start at the motor, and the train ends of to the output which drives a wheel, for instance. (see screenshot below)

Here is what I did to mate the gear subassemblies:

1) Put a coincident to each gear face.

2) Distance the shaft axis to the gear's radii.

3) Coincident the shaft to a fixed plane so it won't move around.

4) Finally, add a gear mate with the appropriate gear ratio.

Problem:

After finish mating, the shaft (and thus the gears) cannot be turn, which shouldn't be the case! So I disassemble and reassembled (a total of 5-6 times already!), sometimes, the entire train can rotate, so good I thought to myself, and I saved it. Later, I opened the assembly, same problem again! The gears cannot be rotated. Only this one shaft can be rotated, which of course, rotates the entire train. But why only this one shaft? I'm so depressed as I spent the whole night troubleshooting this.

What could be the cause? Previously, I used SW 2007 and no such thing has occured before.

Note:

W/o the shafts, i.e., just the gears floating in mid-air, every gear in the train can rotate with no issues, even after saving & opening the assy! This is the ideal condition, but with the shafts added, it's a different story. This is so strange! I followed Deepak's gear assy guide (should go down as a section in the bibles of Solidworks 2009! ) with no issues. Once I added the shaft and formed a new subassembly, the problems start to appear, with the gears unable to rotate like they should.