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  • From: Bill Jones <billj AT harborside.com>
  • To: Homestead mailing list digest <homestead AT lists.ibiblio.org>
  • Subject: [Homestead] Personal Elevators
  • Date: Sun, 23 Jan 2005 15:37:57 -0800

I first toyed with this idea when I was a kid. Imagine that you have a counterweight (box of rocks) connected via a pulley to an elevator car (of your own design, but must be fairly sturdy). If you could just vary the counterweight, you could make the elevator accelerate upward or downward. If you're willing to accept some fairly strict constraints, it would be a vast improvement over the stairs.

First, energy is only free if it's a zero sum game, i. e., you ride up as much as you ride down. It's not practical to send down an empty car for a load of bricks over and over. Second, it's not easy to adjust the counterweight by much without something more elaborate, so the load in the car should always be the same. That's no problem at all if only one person uses it. It could be balanced for the heaviest person in the house, usually dad; mom or one the kids would have to wheel in some ballast (like a sand bag or something) in order to be able to disconnect the car from its hooks (a sort of free safety feature), after which it would function just as if dad were riding.

The easiest way to control the car is to have a counterweight that weighs just a little less than dad and the elevator car combined. A smaller counterweight with a pulley of its own, and a rope leading down to the elevator car (passing through the ceiling), sits on top of the larger counterweight. When you pull on the rope from inside the car, the small counterweight lifts off of the larger one, and you and the car become heavier than the counterweight, so you start to move down. When you let go of the rope, you start to reverse direction. You can probably find a way to clamp the rope to the side of the car so you don't have to keep pulling up on the rope.

With a system like this you can travel all day among any number of floors, and stop on a dime. I can even think of an easy way to make the counterweight slightly more variable, which can be used to smooth out the ride or accommodate packages or loads of veggies. You could just have a tank of water on the counterweight and one attached to the car, with a long slackened siphon hose between them. By pumping water up to the counterweight, you can make the elevator lift a larger load on command, with absolutely no fancy hardware of any kind. The thing that really makes this worthwhile is that any water pumped up does double duty, changing the amount of upward force by twice the weight of the water; that's because the weight of the car decreases by the same amount the the counterweight increases (or vice versa, if you've dropped off your stuff and are preparing to head downward).

I got a sharp stick in the eye the other day, and my recuperation has really left me behind with pruning Japanese plums, but they say it's supposed to rain on Tuesday. Maybe there'll be more time for posting, but I'll believe in that rain when I see it.

Bill
S. Oregon coast




  • [Homestead] Personal Elevators, Bill Jones, 01/23/2005

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