9

I bought a bike hoist which I modified to use to raise and lower a bar that acts as a drying rack for damp clothes in my laundry room. I now have the following setup: current setup The problem is that when I pull on the rope attached to the wall, the right side of the bar goes up while the left side stays down. Eventually the left side of the bar also starts to go up, but by this point all the clothes on hangars have slipped down to the left side.

Is there a way to modify this pulley setup in order to have the bar raise and lower levelly?

  • 2
    This arrangement lets the bar tilt side to side based on the balance of the laundry (and friction). The best way to ensure that it goes up evenly would be to conver it to use two pull-ropes, one for each side, and pull them together. – Johnny Aug 2 '16 at 17:32
  • Couldn't you also stand on the left side and pull the rope at the same time as you are lifting the left side of the bar (as high as you can) helping it up? – Viktor Mellgren Aug 3 '16 at 7:56
  • 1
    The reason it works for a bike is because the bike's center of mass is lower than the attachment points while on the bar it is at the same level. – ratchet freak Aug 3 '16 at 12:43
17

As both bib and Johnny have said, the simplest way to do this is to use two separate ropes. You can either manually pull on both ropes at the same time, or the ropes can be tied together prior to each reaching its first pulley away from the wall (A & B in the image below). Alternately, as Alchymist mentioned in a comment, you can use a single rope with the middle of the rope at the wall and the two ends the attachment points at the ceiling.

Using the pulleys you already have, and keeping the location you are pulling from the same as you are currently using, you can do something like:

Show using two ropes

Pulleys A and B can be located adjacent to each other. You could, of course, use one double-pulley block for A+B. However, I assumed you would want to use the materials you already have on hand.

  • 1
    I've got a commercial version and it works just like this (with the double pulley you mention) – Chris H Aug 3 '16 at 10:33
  • 2
    I have worked backstage at theatres and this is the approach used for backdrops also. The only difference being that the bottom pulleys are replaced by spooling the rope round the bar instead, allowing it to roll up/unroll the backcloth. You only need a single rope, however, rather than tying two together at the wall. – Alchymist Aug 3 '16 at 13:45
  • Just wanted to say that I implemented this solution today and it works like a charm! – derNincompoop Aug 7 '16 at 13:13
11

In theory, a perfectly balanced load and frictionless pulleys would result in a level rise.

But lack of balance and friction are always with us.

The simplest way to ensure a level rise is to use two separate ropes, tied together on the pulling end, similar to the mechanism for venetian blinds. Note that the load is divided by 4 in the current setup (two movable pulleys in series). If you use two ropes each with one movable pulley not in series, the load will only be divided by 2, but will move up twice as fast.

5

OR you can use deep notches in the bar to separate and fix the clothes hangers in their places and when the second pulley starts to work and bar levels up in the topmost position your hangers are where you left them.

  • Very clever. I like it! – bitsmack Aug 3 '16 at 6:41
  • Definitely outside the box thinking, but I will be doing this if I cannot successfully implement Mayken's answer. – derNincompoop Aug 3 '16 at 13:47
5

While I don't disagree with Bib, Johnny, or Makyen, you could just terminate the ropes to the ceiling at both ends of the clothes bar, and tie a pull rope to the center of the rope like this: center Pull

the result will pull the bar up in a generally level fashion, so long as the load on the bar is fairly evenly distributed. Fewer pulleys, less rope.

  • At the bottom of its travel, the bar will not always remain level. The connection point (rope split) will divert toward the heaver side. As the bar approaches the top of its travel it will level somewhat. A good suggestion, but not as reliable or controlled as two separate ropes. – isherwood Aug 3 '16 at 12:47
  • If you are physically holding the horizontal cord in the middle, it is the same as having 2 cords. Both sides will travel perfectly level if you pull straight down. The issue with this solution is that you may not be able to reach the cord because it is too high. If you do connect a cord to the center (as though the "pull here" arrow is actually another cord), as long as you pass the cord through an eye at the back wall (if looking at this diagram, back is away from the viewer), both will still pull down at the same rate. – Keeta - reinstate Monica Aug 3 '16 at 14:59
  • You could attach the eye to the ceiling in front of the center point as well; that would help to prevent the bar, or the hangers on it, from crossing paths with the cord. – Dan Henderson Aug 3 '16 at 15:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.