Great work Gutt! There's more to see every time I look!
You're right about increasing the lifting (or pulling) weight by using a block. For every turn of the cable around a pulley, the lifting/pulling capacity is doubled. So, if you have a straight pull of, say, 500kg, add a single pulley wheel and that then becomes 1,000kg, add two pulleys (at each end) and it becomes 2,000kg and so on. It can get to the point, using enough blocks/pulleys, where a child could lift a ton using one hand.