Speed variation is acomplished by increasing/decreasing the pulley’s channel. The return movement of the side flange is caused by the spring.
Everything is accurately modeled except for the spring.
STL (Stereolithography, filesize: 5.29 MB), STP (STEP, filesize: 2.61 MB), IAM (Autodesk Inventor, filesize: 16.2 MB), DWG (AutoCAD, filesize: 8.09 MB)