In Europe, standard is 10 years, although the "Premium" manufacturers like Linde, Still or Jungheirich proudly claim, that they provide the parts for some models for 20 or more years after the end of production.
The fact is, some of their products from 80's and 90's are realy tough "moth....ers", still alive and kicking. So for the OEM's it's a good marketing issue either.