I am making a belt transmission with double SPZ belts. I managed to make one belt via the belt feature, but how do I duplicate this to create a second belt while still maintaining all the belt properties in Solidworks? So solidworks still sees this as a belt, with the paths and everything, and adjusts the lenght if I change the center distance of the pulley's or their size.
Arno,
I'm not sure I understand your question. If you are able to make a proper belt in SWX then you know it is composed of a path and profile and that if you are using a fixed length for the belt then one of the pulleys must be free to move in order to allow the path to go where it has to.
Are you simply using a double groove setup and two belts side-by-side? You could easily do this by copying the belt part into the assembly for the second instance. You could also just use a double belt profile so the belt pair would be two bodies in the belt part file.
If you could post a picture or the assy and part files we could perhaps offer more help.