Help with Pulley System

  • geofk12
  • geofk12's Avatar Topic Author
  • Offline
  • Junior Boarder
  • Junior Boarder
More
13 years 4 months ago - 13 years 4 months ago #129662 by geofk12
Help with Pulley System was created by geofk12
Attached is my drawing of a pulley system that I've modified. PLEASE give me some feedback. See any possible improvements? See any possible problems? Can you explain the ratio to me?

Thanks!
Geof

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129665 by oldtimer
Replied by oldtimer on topic Pulley System
Great picture but that appears to be too complicated for what I assume you are trying to accomplish. Search in the old postings for the RAD or Yo-Yo system. It is similar to what you are trying to do ( I think) but it does not take as many components and parts to make it work. If you are trying to reduce friction, a separate two ring friction saver over the branch will accomplish the same idea and you can set it up and remove from the ground. In your system (It apears to me) that you will have to climb up to the branch first to rig it up and them come down to use it and I think that It can not be removed from the ground (not easily?) or without removing a few parts first. Just wondering . Great diagram thou. Thanks for sharing it. Moss and the other more experienced climbers will soon offer some other suggestions soon.

Please Log in or Create an account to join the conversation.

  • geofk12
  • geofk12's Avatar Topic Author
  • Offline
  • Junior Boarder
  • Junior Boarder
More
13 years 4 months ago - 13 years 4 months ago #129666 by geofk12
Replied by geofk12 on topic Help with Pulley System
This system can be set up from the ground easy. All the knots from the lower pulley to the eight to the blake is designed to allow the climber to reach up and grap a knot (one of the eights) and pull themself up while standing up on the foot loop. This makes tis soooo easy to stand up (if they are a heavy climber)

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129667 by link774
Replied by link774 on topic Help with Pulley System
Neat idea and very nice drawing. I'm not familiar with RAD or Yo-Yo systems, so take my comments with a grain of salt.

Somebody correct me if I'm wrong, but the ratio is 2:1, since for every 2 feet of rope you pull, you will move 1 foot. The upper pully is just a redirection, so you don't get any mechanical advantage there.

I think removing this from the ground wouldn't be too hard:
1) Pull down on the two parts of the rope going through the upper pully until you get the whole pully/cambium saver system to the ground. You will have to feed slack to the lower pully.
2) Unclip the upper locking carabiner
3) Pull down on the far left rope to pull the pully/cambium saver back over the branch and down.

To install you can pretty much follow the same steps in reverse:
1) pull the pully/cambium saver system over the branch and back down to your location
2) clip the locking caribiner onto the far left rope
3) feed/clip the rope through the lower pully and then the upper pully
4) pull the cambium saver back into position by pulling up on the left rope
5) take up slack, and tie the friction knots

Not too bad, probably, once you get the hang of it. It is a lot of knots to tie, but I guess you could leave the cambium saver and pully tied into your rope. You could also keep all the knots in the rope between the lower pully and your harness, except the blake's hitch.

- Link

Please Log in or Create an account to join the conversation.

  • geofk12
  • geofk12's Avatar Topic Author
  • Offline
  • Junior Boarder
  • Junior Boarder
More
13 years 4 months ago - 13 years 4 months ago #129668 by geofk12
Replied by geofk12 on topic Help with Pulley System
You are correct Link774 - I keep all the knots tied. I only have to retie the blake.

Are you sure this is set up as a 2:1? The climber pulls up 50% of their with weight & goes 1/2 the distance on each pull?

Geof

Please Log in or Create an account to join the conversation.

  • SRT-Tech
  • SRT-Tech's Avatar
  • Visitor
  • Visitor
13 years 4 months ago - 13 years 4 months ago #129671 by SRT-Tech
Replied by SRT-Tech on topic Help with Pulley System
its too complicated and cluttered, lose all those figure 8 knots, they are not needed.

what i mean is you dont need all those stopper knots and figure 8 knots. Attach the upper pulley with a figure 8 and carabiner, no prob,, the lower pulley can be attach directly to the harness with a biner. The only knots /hitchs you need are the Blakes and one figure 8 on the upper pulley. The stopper knots by the cambium saver are not needed the saver stays in place on its own (wieght of rope). You can eliminate that knotty cluster at the bottom by using a splitail.

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129672 by moss
Replied by moss on topic Help with Pulley System
I believe this is 3:1 (could be 4:1, call in the math experts) and it can be tied way, way more simply. As Oldtimer mentioned, look at RADs or Yo-Yo systems as applied toDdRT climbing also known as a Canadian System to certain swamp climbers
DdRT RADs system

Tengu has also designed a very simple equivalent system for adding additional mechanical advantage to DdRT 2:1 system (doesn't require Grigri or ID inline, he calls it the Super System. I don't have any photos online, maybe he can post something.
-moss

Please Log in or Create an account to join the conversation.

  • geofk12
  • geofk12's Avatar Topic Author
  • Offline
  • Junior Boarder
  • Junior Boarder
More
13 years 4 months ago - 13 years 4 months ago #129673 by geofk12
Replied by geofk12 on topic Help with Pulley System
SRT-Tech:
The reason for not attaching the lower pulley to the saddle is that there is the potential for a finger/hair/clothing pinch on a client climber (especially a child)

All the eights below the lower pulley allow the climber to reach up and easily get to a standing position on the foot loop.

Moss: Everything above the lower pulley is the super system as I've been taught.

Thanks for all the great feedback!

Geof

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129674 by moss
Replied by moss on topic Help with Pulley System

Originally posted by Geof_K
Moss: Everything above the lower pulley is the super system as I've been taught.


I was just looking at your drawing again and realizing that. All the extra F8's were throwing me off.
-moss

Please Log in or Create an account to join the conversation.

  • SRT-Tech
  • SRT-Tech's Avatar
  • Visitor
  • Visitor
13 years 4 months ago - 13 years 4 months ago #129676 by SRT-Tech
Replied by SRT-Tech on topic Help with Pulley System

Originally posted by Geof_K
SRT-Tech:
The reason for not attaching the lower pulley to the saddle is that there is the potential for a finger/hair/clothing pinch on a client climber (especially a child)

All the eights below the lower pulley allow the climber to reach up and easily get to a standing position on the foot loop.

Moss: Everything above the lower pulley is the super system as I've been taught.

Thanks for all the great feedback!

Geof


aahh!! i thought this was a personal system. I can see the issue if there are other users on the system!

:)

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129677 by link774
Replied by link774 on topic Help with Pulley System

Originally posted by SRT-Tech
The stopper knots by the cambium saver are not needed the saver stays in place on its own (wieght of rope). You can eliminate that knotty cluster at the bottom by using a splitail.

I think the stopper knots around the cambium saver are there for ease of positioning and removing while on the ground. I guess you could use a slip knot to pull it up, and then remove it, but why not just leave a figure-eight there all the time, because you always need it in the same position on the rope?

- Link

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129678 by link774
Replied by link774 on topic Help with Pulley System

Originally posted by moss
I believe this is 3:1 (could be 4:1, call in the math experts)


I'm a math expert :) Here's how to calculate it:

In a pulley system, the mechanical advantage is equal to the number of ropes supporting the movable pulley. Fixed pulleys only change the direction of the force, they do not change the force required to lift a load.

Think of lifting a 100 pound block by pulling down on a rope threaded through a pulley above you. You need to pull with 100 pounds of force to lift the block.

In the situation Geof_K's diagram, the climber's weight is supported by two ropes, one out of each side of the pulley attached to the harness. Half of the force is provided by each.

Here is a link that might explain it better than I did:
Pulley Link

We have exactly the 'Movable Pulley' situation (2nd diagram) in the Geof_K's rig.

- Link

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129679 by jimw
Replied by jimw on topic Help with Pulley System
3:1 . . .no . . . 4:1 . . . no . . . 2:1 . . . wait!!

What do those figure-8s do at the cambium saver? Will they pass through it?

Strange configuration!

Peace.

Jim

Please Log in or Create an account to join the conversation.

  • geofk12
  • geofk12's Avatar Topic Author
  • Offline
  • Junior Boarder
  • Junior Boarder
More
13 years 4 months ago - 13 years 4 months ago #129680 by geofk12
Replied by geofk12 on topic Help with Pulley System

In a pulley system, the mechanical advantage is equal to the number of ropes supporting the movable pulley.

Link: Thank you for that simple & clear answer! Perfect!:D

Please Log in or Create an account to join the conversation.

More
13 years 4 months ago - 13 years 4 months ago #129681 by Tom Dunlap
Replied by Tom Dunlap on topic Help with Pulley System
These illustrations may help:

http://www.alberta-ck318.freeserve.co.uk/tackles.htm

Strong limbs and single ropes!
This email address is being protected from spambots. You need JavaScript enabled to view it.

Please Log in or Create an account to join the conversation.

Time to create page: 0.540 seconds
Powered by Kunena Forum