Simulating cable operated assemblies

I'm scratching what hair is left on my head over this one. Ineed to model a cable operated assembly - very simple - the cableis attached at one end to a slider that, er, slides up and down atrack, and at the other end it pulls on a lever . A spring providesthe counter balance force. In between the slider and the lever thecable goes around a pulley.....and that is the problem.

Obviously the length of cable is fixed, but the section that goesround the pulley will vary, so I cannot set up a fixed length forthe cable as I don't know how much cable is around the pulley atany one time as the angle around the pulley varies with the slidermovement.

The belt mate doesn't work here. Any ideas how I can fix the lengthof the cable and get the resultant motion of the lever when I movethe slider?SolidworksAssemblies