Multifunctional exercise device with a pulley system

[rysio]

Hello everyone. I come to you to ask for help, I have to design an exercise device with a pulley system. The project was supposed to be done by two people, unfortunately after completing my part (3D model), I was left alone with the calculations, the deadline for submitting the work is by the end of the week
I am looking for a person who will help me understand what needs to be calculated and what formulas to use to make the calculations correct (I will calculate everything myself, I just need some guidance), I still have to finish the model so I won't have time to do everything myself, and I don't want to lose my grade due to someone else's negligence. Thank you for any help
This is what my model looks like for now

 

[3DDave]

Compare the travel of the apparatus to the travel of the weight to understand the ratio of effort to movement. So, if the pull-down moves 10 inches and the weight moves 5 inches then the force to pull down is the inverse (F1 * d1 = F2 * d2; F1/F2 = d2/d1) or 1/2 the weight.

 

[rysio]

but how can I check the distance by which the weight will move up if I don't have a physical model

 

[3DDave]

Since the cable is stiff and doesn't change length in a notable way then you use the grade school education you should have had about how pulleys work.

https://www.youtube.com/watch?v=6GuldysCVjI

https://www.youtube.com/watch?v=XgLsBgmGigA

 

[rysio]

Unfortunately, at school the topic of blocks was practically omitted, only brief information about them was provided. I've seen these videos before and, just like in the second video, in the 2nd example it's a bit similar, but here everything is on one rope, which is incomprehensible to me with my project because in the videos the weight is attached to the pulley and in mine it's attached to the end of the rope ;(

 

[3DDave]

They also show the force on the rope. The force on the pulley is the force applied to the frame.

 

[rysio]

so if I understand correctly, where the roller moves, it increases the distance or reduces the weight, i.e. in the red one, no roller moves, so at the end there will be 100 kg, in the green one, one roller moves on the red/green connection, so the weight is 1/2, so 50 kg And in the blue one, two rollers move, so the weight is 33.3 kg?

 

[SWComposites]

First, I don't see how this thing works unless forces are applied to all three (arrow) points at the same time.

Second, draw a force free body diagram of every pully and attachment point. Then work out the loads at each starting with the known values.

 

[IRstuff]

First, I don't see how this thing works unless forces are applied to all three (arrow) points at the same time.

The null position of each part is a stop; the OP picture is of an actual machine, similar to below

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[rb1957]

I think it works as three different pulls.

Pull on the red line. The middle block, attached to the green line, will just move up (with the green line being slack) until the red line is a straight loop over the top of the machine (something you can show with your 3D model) and the 100 kg weight is balanced by a 100 kg pull, yes ?
I think you get the same result if the green line is locked at it's starting length ... so maybe the exercise machine locks the inactive cables ?

If you pull on the green line, with the red line locked, I think the first block set shows that two red lines are balanced by 3 green lines, so green pull is 100 kg,



"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[rysio]

This video clearly shows how the individual rollers work together during each exercise

https://youtu.be/M0ws3SbOPaE?si=6UA_l1X-B7tiWaGB

 

[SWComposites]

ok, well, the OP's figure didn't show the stops that have to be on any 2 of the pulls.

So there are 3 separate load conditions to analyze.

 

[rysio]

That's how I noticed that when exercising, the red rope does not move, no rollers move, when exercising the green rope, one red-green roller moves, and when exercising the blue rope, two rollers, red/green and green/blue, move. I've lost track of how to calculate it correctly,(

 

[3DDave]

Looks like a long con to post the video.

 

[IRstuff]

I think if you pay careful attention to the woman in the video using the machine, you'll see that the amount of cable motion she pulls for any specific part of the machine is the same amount of cable motion at the weight, so moving anything by a foot results in the weight moving a foot.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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