# Can I use this simple pulley system to lift a large 100lb box?

Problem: I have a 98 lb box with dimensions of 45"l x 41"w x 27"h that holds a holiday decoration. I need to lift it to a shelf I made that is 103" above the floor. The space I have between the shelf and the ceiling is 32", so I have 5" of clearance to get the box on the shelf. Second part of the problem is I am an EE trying to be an ME ;)

At first, I was going to try a 100 lb bicycle/kayak lift that has two hooks and reinforce holes on the front and back of the box and lift it that way. That method may work, but it needs more than 5" from the ceiling to the top of the box so I would also have to be under the box pushing it up and in.

My other idea was this simple pulley system. The plan is that I can lift the box as high as possible up to the edge of the shelf with one person holding the line, and I push the edge of the box onto the edge, then have then loosen the line to push it the rest of the way. I'm looking for the best way to do this.

1. Where to find the pulleys? I hope I can find a pulley for the ceiling joist that has a plate with holes for one bolt in front and one in back of the wheel to screw into a 2" joist. And I need a pulley with an eye on the bottom to connect to the box.
2. How to connect the box pulley to the box? Maybe a simple dual sling of a two ropes to go under the box? Or spreader bars from 2 x 4s?
3. Other than the ceiling pulley being able to clear the box and have the ceiling eyelet being over the shelf to be able to push the box over the end of the shelf, how should I properly calculate the space between the eyelet and the ceiling pulley.

The shelf is the brown rectangle on the left. The ceiling joist is oriented inline with the rope and pulleys, so the ceiling pulley would have a bolt to the left of the wheel and a bolt to the right of the wheel in the image.

• Putting the materials in 2 or 3 smaller boxes may be more practical . So one person could lift the boxes by hand. Jan 2, 2023 at 19:55
• That's what I told my wife ;) I was just going to put them in plastic bags. The problem is this is one of those 12' skeletons. Let chest and leg pieces are almost as big as the box. It all packs away strategically to make the most use of the huge box. Jan 3, 2023 at 13:01

It's time to brush up on your force diagrams!

Figure 1. As angle a goes to zero the tension in the rope and on the ceiling anchor point goes to infinity.

I suggest a vertical pulley system to get the box close to the ceiling (which should be doable) and a pull-out shelf or open fronted drawer unit to pull out under the suspended load. Then lower the load onto the shelf, let the rope go slack and then push the shelf in. You could use multiple pulleys to reduce the effort required and could then safely hold the load in one hand while working the shelf with the other. A safety brake or tie-off point on the line is another option.

From your drawing, it seems the two pulleys attached to the ceiling are rather far apart. Because of this, the force needed to lift your box will increase as it gets higher, because of the trigonometry involved.

This example shows what I mean: you would expect the box to be in equilibrium with $$W2 = 80$$ kg, if you assume all ropes to be vertical, but because of the angles $$\theta_i$$, you can only lift a weight of $$W_2 = 50$$ kg by applying $$W_1 = 40$$ kg.

If you only have 5" above the shelve, some of which will be occupied by the pulleys, your ropes connects to the box would become almost vertical when the box is at the top, which greatly increases the force need to lift the box. (At angles $$\theta_{1,2} = 90^{\circ}$$, you would theoretically need an infinitely large force to keep the box in equilibrium.)

I think you could make a system like this that works, but make sure your ropes connected to the box remain as vertical as possible.

• I can't vote up yet because it seems every new stackexchange/stackoverflow you post in, you start over. I'll try to remember to come back once I have 15 points. Thank you! Jan 3, 2023 at 13:14

In similar situations I have improvised a ramp. This makes things much safer imho.

I did this to get solar thermal panels up about 15 feet. I used 4 scaffold boards and joined them 2 in series. The joint made for a stable and safe halfway point in the pulling process.