I use a block and tackle system to hang my RO III pendants, but the same setup could be used to hang a hood that weighed hundreds of pounds or more.
My setup is a 4:1 ratio, but you can go as high as about 8:1 before friction starts to diminish your returns.
You can build your own block and tackle with parts from McMaster or Grainger (shives and pulleys) or you can purchase main sail gear from a boating supplier. I think a company even sells a 4:1 setup for hanging stuff in your garage. You can use a winch or caveman power to raise and lower your hood. I purchases a right angle gear motor (windshield wiper drive) but have yet to hook it up due to laziness.