It sure seems like magic when you put a little pressure on that small lever and all that work just happens, doesn't it? /w3tcompact/icons/smile.gif
My guess is that you'll get different answers to this question, but I'd say the magic is best summed up as: PSI - Pounds per Square Inch. If you think about the pressure that the pump creates, say 2500 psi, that means that 1 square inch of it can lift 2500 pounds of weight. (I'm over-simplifying here, because flow is involved too, but everybody always accuses me of over-complicating things, so this time I'll try it the other way.)
Now, pretend a cylinder is 3 inches square (I know the ones on your tractor aren't square, but it's easier to calculate the surface area of a square cylinder. I'm over-simplifying, remember? /w3tcompact/icons/smile.gif) That's 3" x 3", or 9", of surface area on the piston, with 2500 pounds of pressure on each inch. A magical amount of stuff can get done when you've got that much potential force at your command.