Block and Tackle Pully System - How do I use it?

After doing some searching on the gear forum, I have not found much discussion about block and tackle pulley systems.


I have acquired a an older set that the owner utilized for lifting and hanging deer after hunting season and the ropes look pretty rough. I'm planning on 'restoring' the set but outside of what the past owner has used it for, I'm not sure what I'd use if for.

What/how do you folks utilize this kind of gear. Is there a modern alternative that you utilize?

Basically, the amount of force applied by a pulley(s) is multiplied by the number of times the pulling cable is added.  With a single pulley attached to the ceiling, and one length of the rope supporting the load, a pulling force of 50lbs results in a pulling force of 50lbs on the load.

If you add a second pulley wheel (one on the ceiling, and one at the load), you double the force.  50lbs of force on the rope yields 100lbs of force on the load.  But, the amount of rope you have to pull doubles.  So, in the first example, if you pull 1 foot of rope on the ceiling pulley, you lift the load 1 foot off the ground.  With the second example, you need to pull 2 feet on the rope to lift the load 1 foot.

With three pulleys, you increase the force 3 times, but have to pull the rope three times as far, and with four pulleys, it's 4X the force, but four times the length of rope pulled.

In each case there is conservation of energy,  With four pulleys, it's 4X the force, but you have to pull 4X as long.

Does that make sense?  You could use pulleys for any heavy load you can't pull on your own.  Maybe a engine out of a car, lifting bales of hay to the second floor of your barn, or using pulleys to tighten fencing wire? Lots of applications.

Further to Michael; each pulley on the moving load increases force.  Pulleys on stationary anchors or motive force redirect motion.
And with a cunning arrangement of pulleys, UHMW rope and large logs you can pull the rear end off a Honda CRV.
Explain that one to your partner...

To be even more concrete: a block and tackle is basically what we used for winching before we had winches. Think of anything you might use a winch for...dragging stuff, picking up heavy stuff, bending things that are hard to bend...you can use a block and tackle for that.  

Timothy Norton wrote:

What/how do you folks utilize this kind of gear. Is there a modern alternative that you utilize?

We use them daily in industry.  The modern 'take' on the block and tackle is called a chain fall.  it uses a continuous loop of chain rather than a length of rope. (the more mechaincal advantage or number of pullets increases the length of rope needed to lift the object.)  the loop allows one person to raise an lower the hook/piece without belaying a line or tying off.  

You have a really cool piece of history there. I agree with what the previous folks said in terms of how they work. It is a little bit difficult to see in the photo but it looks to me like you have one that could be used to stretch wire, as in stretching one strand of barbed wire at a time on a fence. One word of caution; if you replace the rope, take care to use a rope that is not elastic and will not significantly stretch under load.  The mechanical advantage that you get with these can enable you to create an impressive amount of tension and if something breaks or gives way, you can end up being stuck by something that is propelled at an equally impressive speed. Please don’t ask how I know, it’s embarrassing.

Set it up and try it out. Is the condition of the rope so bad that you can't practice with maybe a 5 gal. bucket of water? I've used set-ups with similar looking rope to lift a 200 lb deer. I did use leather gloves to handle the rope.

I use a block and tackle with a long spring to make it easier to open the garage door. Also, I have repelled down into a pit and easily pulled myself back up using a cheap block and tackle from a known discount hardware wholesaler.. Others raise their bicycles to store them out of their way into the rafters using the pulley system.

In case you're new to lifting / hoisting:  if it's heavy enough to need mechanical advantage to lift it, don't stand under it.

To phrase the mechanical advantage a little differently:  nothing is free, so if it's easier to lift the thing, you're paying for that somehow.  With block and tackle, the trade-off is that to get the job done with less force you must pull more rope.  If you can lift at most 50lb and use pullies to lift 200lb 5 feet, the force you apply drops to about 12.5lb, but you pull 20 feet of rope.

The military rigging manuals:

https://dn721901.ca.archive.org/0/items/u-s-army-guide-to-rigging/U.S.%20Army%20Guide%20to%20Rigging.pdf

Page 106 begins the section on pulleys.

also:

https://www.umt.edu/media/wilderness/toolboxes/documents/tools/Rigging/Army_rigging_manual.html

My favorite rigging books otherwise:

Construction Safety Association of Ontario rigging manual

Moving the Earth - Herbert L. Nichols jr.

We brought back our 'handy billy' when we left our boat for dry land.

It's a long length of cordage threaded through two blocks, one of which has a jammer.

We use it whenever we want to move something with (a lot) less effort. It's invaluable for pulling our woodchipper onto our trailer, and this year we're going to use it for getting an apple tree upright from its precarious 45 degree lurch. (our tenants put in a pond alongside it, and chopped off the roots on one side :o((

A really useful piece of kit to have to hand, just make sure the cordage, the blocks, and the attachments are rated for the weight you're proposing to put onto it. also, make sure the cordage is free flowing (ie flake it - google that! ) and, you're not stood amongst it, in case it takes you with it!

I'd also echo the recommendation for leather gloves, (to avoid rope burns ) as well as the "don't ask me how I know, it's too embarrassing" (and extremely painful)