I've got an old modified Mercedes sprinter. It has over 500,000 and all with the original clutch!
Only thing is finding parts for it is a bit hard now, but I'm hoping I'll get a few more years out of her yet :D
Have you seen this video?
https://www.youtube.com/watch?v=Z_i1MZQSB44
I know this video shows a pipe example, but it is very detailed and you can see the mechanism working clearly. Should give you a good idea :)