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Hauling systems - (Split from: Win lots of shiny kit!)

Mark Wright

Member
[gmod]Topic split from competition thread: https://ukcaving.com/board/index.php?topic=26405.0[/gmod]

StarburstCLA said:
What started as a 1:2 hauling a bag up the stairs, became a 1:4 hauling my partner up the stairs, became a 1:4 hauling myself up my loft hatch. Progress is being made!

You need to re-calculate your mechanical advantages. Your photograph hauling the bag up the stairs is a 3:1.

If you set up a similar system on the haul line you'll have a 9:1.

Mark
 

mikem

Well-known member
& 1:2 would mean you'd made the situation more difficult!

2:1 is an assisted handline, so rope tied off at top, running down through attachment on haulee, & back up to top; or being tied off to haulee, run through attachment at top & being hauled from below (either by haulee, or somebody else).
 

Mark Wright

Member
mikem said:
or being tied off to haulee, run through attachment at top & being hauled from below (either by haulee, or somebody else).

Not sure about your last example. That's a 1:1. The pulley has to move to give a mechanical advantage.

Mark
 

PeteHall

Moderator
Mark Wright said:
mikem said:
or being tied off to haulee, run through attachment at top & being hauled from below (either by haulee, or somebody else).

Not sure about your last example. That's a 1:1. The pulley has to move to give a mechanical advantage.

Mark

If it is the haulee, doing the hauling, they are moving, so there is a 2:1 advantage. If someone else is hauling from the bottom, there is no advantage.
 

Mark Wright

Member
PeteHall said:
Mark Wright said:
mikem said:
or being tied off to haulee, run through attachment at top & being hauled from below (either by haulee, or somebody else).

Not sure about your last example. That's a 1:1. The pulley has to move to give a mechanical advantage.

Mark

If it is the haulee, doing the hauling, they are moving, so there is a 2:1 advantage. If someone else is hauling from the bottom, there is no advantage.

If the haulee is doing the hauling then there is certainly SOME advantage.

Mark
 

Mark Wright

Member
Examples of 3:1, 5:1 and 9:1 mechanical advantages configured in auto-lock hauling systems typically used in the rope access industry.

The 3:1 is the most commonly used system for hauling a typical 100kg casualty in the workplace.

The system used in the DCRO (Titan) post is a 3:1, however this is only theoretical as there is a lot of friction in the system which will reduce this.

The lower 'deviation' pulley doesn't help but if this wasn't used then its likely the tripod would be pulled over. The 3:1 mechanical advantage is significantly increased by having lots of people pulling the haul line and using high efficiency, ball bearing pulleys.

Mark
 

Attachments

  • 3-1.pdf
    414.3 KB · Views: 115
  • 5-1.pdf
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  • 9-1.pdf
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Fulk

Well-known member
The 3:1 mechanical advantage is significantly increased by having lots of people pulling the haul line . . .

Obviously the effort needed is considerably decreased by having lots of people pulling, but how does the effort put in affect the mechanical advantage, Mark?

I post pictures the easy way, by clicking on 'Attachments and other options' (just below the window), then going to 'choose file'; if this is what you do and it doesn't work for you, I've no idea what to suggest.
 

Mark Wright

Member
Fulk said:
The 3:1 mechanical advantage is significantly increased by having lots of people pulling the haul line . . .

Obviously the effort needed is considerably decreased by having lots of people pulling, but how does the effort put in affect the mechanical advantage, Mark?

It doesn't. I mean its a lot easier the more people are pulling.
 

Mark Wright

Member
Fulk said:
I post pictures the easy way, by clicking on 'Attachments and other options' (just below the window), then going to 'choose file'; if this is what you do and it doesn't work for you, I've no idea what to suggest.

That's exactly what I did
 

PeteHall

Moderator
Mark Wright said:
Fulk said:
I post pictures the easy way, by clicking on 'Attachments and other options' (just below the window), then going to 'choose file'; if this is what you do and it doesn't work for you, I've no idea what to suggest.

That's exactly what I did

Possibly to do with file size?
 

Fulk

Well-known member
Or type of file (I've tried posting tifs before, and it doesn't work with them). (Sorry Mark ? I hope my remarks didn't come across as too patronising.)
 

mikem

Well-known member
Must have been too early in the morning, you're right, pulling from the bottom isn't a 2:1, just makes more efficient use of our weight to haul with, so less effort than hauling from above.
 

Ian Ball

Well-known member
Allowed file types: gif, jpg, jpeg, pdf, png
Restrictions: 6 per post, maximum individual size 11000KB



 

aricooperdavis

Moderator
How about this? Order should be 3:1, 5:1, and 9:1. (I extracted the images from the PDFs using the
Code:
[url=https://www.xpdfreader.com/download.html]Xpdf[/url]
command
Code:
[url=https://www.xpdfreader.com/pdfimages-man.html]pdfimages[/url]
, which is very useful for this kind of thing.)
 

Attachments

  • 3-1.png
    3-1.png
    533.7 KB · Views: 127
  • 5-1.png
    5-1.png
    605.9 KB · Views: 127
  • 9-1.png
    9-1.png
    671.7 KB · Views: 130

PeteHall

Moderator
Mark, in terms of mechanical advantage, I'm struggling to see the difference between the second two set up's. Perhaps I need to set them both up to watch how they behave, as they look to do the same thing... :confused:
 

JoshW

Active member
PeteHall said:
Mark, in terms of mechanical advantage, I'm struggling to see the difference between the second two set up's. Perhaps I need to set them both up to watch how they behave, as they look to do the same thing... :confused:

Thank god, I thought I was the only one!
might have a play around tomorrow, although I'd suspect by the time you're getting up to 5+:1 the additional friction added to the system can negate the different 'felt'. sure someone smarter than me can confirm at what point 'the benefit' really starts to tail off though!
 
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