to simplify....less mechanical advantage = more slippage, picture a 800# weight strapped to a pulley system and its 10' in the air...1st gear would mean pulley system is at 20:1, you will pull 20' of chain to lift that weight 1' and itll be easy to do. 4th gear would mean its at 1:1...you would be able to apply force, but eventually the chain will slip through your hands or you will be 10' in the air and the weight will be on the ground.