Abstract: Tire making machines and driven assemblies for use in a tire making machine. The driven assembly includes a motor having a drive shaft. The drive shaft extends along a length and has a keyway extending along a portion of the length. The keyway includes a bottom surface, sidewalls, and a ramp surface. The driven assembly also includes a driven hub operatively connected to the drive shaft and having a hub keyway. A key is received in the keyway and the hub keyway for operatively connecting the drive shaft and the driven hub. The key includes a bottom surface, side surfaces, and a curved surface. The curved surface and ramp surface include transverse sections having a curved profile, and the curved surface fits into the ramp surface.