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Originally Posted by b.r.e.
Look at the size of the motor on this car jack
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It's a biggie, to be sure, but remember the jack (and motor) are probably designed to lift two tons at least, possibly even as much as four tons. The OP only needs to lift 200lbs. Even considering he might lever it for more stroke vs. force, that's still presumably only a modification factor of two, or the equivalent of 400lbs that he's meaning to lift. For that reason, he could get by with a smaller motor, presuming the same jack was for sale with a choice of motors
He still hasn't mentioned to what degree speed is a factor, which means quite a small motor could do, hypothetically, it just depends on how long he wants to wait around for the thing to lift. Watch this guy using a hydraulic jack - you can see that it's not taking him much effort at all to lift the car. They have a fancy name for the jack, but it's still just a basic hydraulic jack like the first one I posted from Canadian Tire.
http://www.youtube.com/watch?v=jQpeEXIC3JI
edit: on closer inspection I notice he's not lifting the car in the video, just bracing the trunk assembly. Still, there is/can be considerable force on the jack, but it's still very easy to manipulate the pump. I remember my Dad using one of the first Canadian Tire versions I posted to quite easily force up the corner of a large gazebo while he fitted a new permanent post - lifting it was a snap, it just took a lot of pumps. By "pumps" I mean pumping the jack - only one cylinder was used in the gazebo project.