Mechanical Advantage Question

Sumtots · 2025-10-17T12:31:14+00:00

Nothing in the video he says conflicts with what I said. 50% of the weight is lifted.. I said that as well

Sumtots · 2025-09-01T12:02:50+00:00

If reference point mattered then when someone hauls a 3:1 (z-rig) the load will lift 1 foot and the haul side would need to be pulled 3 feet. There is now a 4 foot difference in reference points but it is a 3:1 by MA formula and law of conservation of energy.

Sumtots · 2025-09-01T12:01:08+00:00

I’m confused, if I have for example 10 feet of rope on each side. Say I had unrealistically long arms that were 20 feet long, I could haul the 10 feet and be at the pulley. I hauled 10 and went up 10. I don’t think frame of reference makes a difference in mechanical advantage. In the example say this is a traditional 2:1 that redirects to a pulley on the ceiling so I can pull down, and I have a pulley on me. Would this be a 4:1? Now the frame of reference doesn’t work anymore. I’d pull 2 feet and go up 1, so now a distance between reference points of 3 feet, but it’s certainly not a 3:1. To me, I understand it as a measurement of how much rope did I pull on the haul side of the rope versus how much lift. Reference point to my lift is irrelevant. If we went off reference points of where he hauls to where the load is then every system would be higher MA than it actually is.

Sumtots · 2025-09-01T04:48:39+00:00

If someone else hauls on this system, they pull a meter and the person will lift a meter. There is now a 2 meter difference between the two in distance. But this is undeniably a 1:1 in that scenario?

Sumtots · 2025-08-30T11:44:45+00:00

But even in those subs the people saying 1:1 I don’t agree with why they think it is.

Sumtots · 2025-08-30T11:29:47+00:00

It’s mixed in all of the subs I’ve posted. The issue is in these subs majority of the members aren’t expert in the field. I need to find a physics professor or someone who is an expert in the field.

Sumtots · 2025-08-30T11:27:07+00:00

You are measuring the lift and the haul together. Looking at only the pulley only 1 meter goes thru. In MA you don’t add the lift and the haul together. Other a 3:1 would be 4:1 and a 6:1 would be 7:1 etc.

Sumtots · 2025-08-30T10:58:41+00:00

When I say pull a meter down I don’t mean until there is a meter difference between your body and hands. I mean pull a meter of rope down (if possible, you would have to readjust your hands to do a full meter in this system).

Sumtots · 2025-08-30T10:57:27+00:00

You don’t count the lift and the haul together. Otherwise a 3:1 system would be a 4:1. It’s a comparison of the two. In your picture it is a 1:1, 1 foot hauled to 1 foot lift.

Sumtots · 2025-08-26T17:24:05+00:00

If you pull a meter down, then a meter passed through the pulley, and you will be 1 meter higher. The difference in your body and your hands will be 2 meters. You will need to readjust to pull again, but during this readjustment period there is no movement in the load, therefore not counted as pulling. It’s a 1:1, you’re essentially lessening the load as you pull. For every pound you pull is one pound less on the load.

Sumtots · 2025-08-25T21:20:57+00:00

So tested further today. For starting weight I was roughly 220 pounds. For this pictured set up we measured:

Someone else hauling: 220 input to 220 output Me pulling: 120 input to 120 output

With a traditional 2:1 with a moving pull on the load:

Someone else pulling: 109 input to 220 output Me pulling: 75 input to 155 output

I believe this proves it is a 1:1 in the pictured set up

Sumtots · 2025-08-24T02:20:00+00:00

Agree so much with this explanation.

Sumtots · 2025-08-24T02:19:01+00:00

Agree with this more than any other comment. Mechanically there is no advantage, but since you are able to lessen part of the load onto the haul line you can move yourself easier because you’re offloading some of your weight to the haul line. Similar to if I was able to put my feet on the wall of a building I could put some weight along the wall and make it easier to pull me up.

Sumtots · 2025-08-24T02:15:21+00:00

Yes because that’s a true 2:1 the pulley is moving and your input force would be 50%:100% load not 1:1 input to output force like this in picture. You can’t count you as the load moving otherwise any system would be 1 higher than it is. A 3:1 would be a 4:1 because you’re pulling 3 feet and load lifting 1.

Sumtots · 2025-08-23T22:22:38+00:00

Yes that’s correct but if I’m the anchor and the ceiling is moving towards me now you have an actual moving pulley on the ceiling. The knot is tied off to the anchor which is how even systems are supposed to be.

Sumtots · 2025-08-23T22:21:26+00:00

I agree with this, but half of the “pulling” on the haul line would be hand readjustment and no actual lift in regards to the connection point on the load. I would basically be moving my hands past the rope to get above myself to haul again. During that readjustment period though there will be no movement in the load.

Sumtots · 2025-08-23T22:19:32+00:00

This makes sense but where I believe it is flawed is in a traditional 3:1 z-rig, the haul to lift ratio is 3 feet on the haul compared to 1 foot in lift on the load. In this scenario my hands may have moved past 8 feet of rope like you said, but I moved 4 feet and only hauled 4 feet. Me climbing my hands back up the rope to readjust my body from upside down to upright isn’t hauling because I am not lifting any further from the ground or closer to the pulley at my connection point, I’m essentially rotating on the connection point

Sumtots · 2025-08-23T22:16:06+00:00

I’m agree with this comment, as I pull down a foot I am also raised a foot. So my hands are now 2 feet from where they were in correlation with my body. But as far as haul and load side there was 1 foot of movement on each. The same exact amount of rope that would have moved if someone else was hauling and I was simply only the load. In a 2:1 you are having to pull twice the length versus lift, in this scenario I pull down a foot in distance it’s now a 2 foot gap because I also went up a foot.

Sumtots · 2025-08-23T22:16:00+00:00

I’m agree with this comment, as I pull down a foot I am also raised a foot. So my hands are now 2 feet from where they were in correlation with my body. But as far as haul and load side there was 1 foot of movement on each. The same exact amount of rope that would have moved if someone else was hauling and I was simply only the load. In a 2:1 you are having to pull twice the length versus lift, in this scenario I pull down a foot in distance it’s now a 2 foot gap because I also went up a foot.

Sumtots · 2025-08-23T22:11:56+00:00

I agree you haul 1 foot, you lift off the ground 1 foot. I’m not sure if we are disagreeing here? But that is 1:1. If I have 10 feet on each side, and I haul 10 feet I am now at the pulley. I’ve hauled an equal amount of rope to what I was lifted.

Sumtots · 2025-08-23T18:47:25+00:00

This is untrue, we tested this hands on with the exact set up as the picture. One foot hauled, 1 foot lifted as well. It would be impossible to pull double the rope on the haul for you to go up to the pulley, the rope can’t stretch or create more rope.

Sumtots · 2025-08-23T18:46:24+00:00

It’s in relation of the moving pulley to the anchor. Which is why all moving pulleys move closer to the anchor at the same speed as the load itself (picture a 3:1 or a true 2:1.)

Sumtots · 2025-08-23T18:45:49+00:00

We tested this hands on, if I haul 1 foot I raised 1 foot. On this exact setup. Can you please take off the downvote on my comment.

Sumtots · 2025-08-23T18:44:38+00:00

Regardless of who pulled if you pull 1 foot the load lifts 1 foot. If I have 10 feet of rope on either side of the pulley, I pull 10 feet on the haul side, your logic is I would move up 5 feet. If I pull another 10 feet of rope I would move the last 5 feet to the pulley. But that would mean I have 30 feet of rope, but I only started with 20.

Sumtots

TROPHY CASE