People think pulleys increase pulling power.

[luthj]

Ummm

 

[67cj5]

Wow, it's absolutely amazing. Pulleys seem so obvious that folks have no idea how little they actually know...

You could spend 30 minutes educating yourself. Nah... I'll just be a keyboard cowboy...

Pulley - Wikipedia

en.m.wikipedia.org

The Pulleys might be able to move a heavier load But unless the cable has the same rating as the Load or Bigger then it is no use trying to move a 27000Lbs Load with a Cable that is rated at 9000Lbs because of the Single fixed points. Because that is where the Cable will break So trying to move a 27000Lbs Load using pulleys and a 9000Lb Cable is Stupid.

 

[67cj5]

Whats 9000lbs winch & rope multiplyed by two, by three, four? I dunno...
Sad state of mechanical aptitude at ‘ExPo ?

I know what they are and what they can do, The Pulleys and the 3 or 4 lots of cable might be able to take the weight, BUT the cable From the Winch to the first Pulley and the Cable From the Last Pulley to the Anchor Point are taking the full weight of the Load Which is WHY all Heavy Lifting equipment run Duel, Triple or Quad Winch/Cables,

That picture with the jeep with 3 Diagrams on it is Wrong because it is the first and Last lengths of Cable which are the weak points.

 

[shade]

The point is no matter how many pulleys you use there is still "ONE" Single cable coming off the Winch and that One Single Cable is attached to a Single Anchor Point and it is those 2 single points which are the weak points, and Regardless of how many pulleys you use because that ONE SINGLE CABLE is still only rated at 9000Lbs.

All those pulleys are just changing the direction of the pull/load, gaining no mechanical advantage. - Is that what you're saying?

 

[shade]

I know what they are and what they can do, The Pulleys and the 3 or 4 lots of cable might be able to take the weight, BUT the cable From the Winch to the first Pulley and the Cable From the Last Pulley to the Anchor Point are taking the full weight of the Load Which is WHY all Heavy Lifting equipment run Duel, Triple or Quad Winch/Cables,

Huh - I always thought the ones I used had a single continuous cable running through all of the blocks.

 

[camp4x4]

Holy hell. My head hurts. I'm going to do this 1 more time:

67CJ5 - ALL the ropes are equally pulling on the object. So yes, a 9000lb rated rope can pull a 27000lb load if the load is split across 3 pulling segments with the appropriate amount of pulleys. I say the appropriate amount of pulleys, because as we've established, it matters if you're connecting back to the vehicle or to a static object from the first snatch block. So each segment is pulling at 9000lbs... 3 pulling segments x 9000lbs of force (at the rated limit) is able to pull a 27000lb load.

 

[67cj5]

All those pulleys are just changing the direction of the pull/load, gaining no mechanical advantage. - Is that what you're saying?

Yes if the cable Is One single cable because that picture that was posted shows a 9000Lbs Winch going through 2 pulleys showing 3 lengths of cable claiming 27000Lbs of pulling power, But if you loaded a 9000Lb Cable with a 27000Lb Load it would Snap the Cable or rip the winch off the truck.,

 

[shade]

Yes if the cable Is One single cable because that picture that was posted shows a 9000Lbs Winch going through 2 pulleys showing 3 lengths of cable claiming 27000Lbs of pulling power, But if you loaded a 9000Lb Cable with a 27000Lb Load it would Snap the Cable or rip the winch off the truck.,

If that's the case, how is it possible for that 9000 lb rated winch to move a load greater than 9000 lbs?

 

[Buliwyf]

Just get your winch and pulleys out. Tape the ground in front of your truck, and paint marker every foot of line. If the winch pulls in 3 feet of cable, but your truck moves only one foot......ta da! You just tripled your winching force.

Your 10,000# winch will only exert 10,000#, but when you use pulleys to parallel 3 cables, each with 10,000# of force on each, boom, 30,000 pounds of force, but 3 times slower speed.

You're just making a rope lever. Every time you add a pulley, you're moving the fulcrum of a lever, further away. We should use the word ''force'' not ''power''.

 

[luthj]

 

[67cj5]

Holy hell. My head hurts. I'm going to do this 1 more time:

67CJ5 - ALL the ropes are equally pulling on the object. So yes, a 9000lb rated rope can pull a 27000lb load if the load is split across 3 pulling segments with the appropriate amount of pulleys. I say the appropriate amount of pulleys, because as we've established, it matters if you're connecting back to the vehicle or to a static object from the first snatch block. So each segment is pulling at 9000lbs... 3 pulling segments x 9000lbs of force (at the rated limit) is able to pull a 27000lb load.

Yes But the 27000Lb Load on the Cable being pulled is being pulled from one single point so that load is all on the first length of Cable from the winch to the first pulley and between those two points the Cable is still a 9000Lb Cable and the load / Strain on the cable does not get halved/reduced until it has passed through the first Pulley.

After that point the cable/s divide the weight/power between them and if the cable is going to break it will be either at the winch or possibly on the length of cable from the last pulley to the Anchor point.

I agree that 3 X the cable can take 27000Lbs but it is that first single length that is the weakest point.

 

[67cj5]

The only things wrong in that diagram is the bottom picture. The pulley on the Jeep bumper is at 18k, not 27k as shown.
To be extra picky, should also be 9k shown where the tail end of the rope attached to shackle on the tree strap.

Yes That is what I was saying, the first and the Last lengths of cable are 9000Lbs.

 

[Hopeless Diamond]

That first length of cable from the winch is no more than any of the other segments between pulleys. If the load was connected to a pully by a single line, that line would be at the full load. It is assumed the pulleys are attached with line/straps, etc that can bear the full load.

 

[67cj5]

Yes, intermediate cable is at 9k also.
So, whats 3x9 ? I forgot, after all this, my brain hurts.

LOL, yeah me too,

 

[MOguy]

All this is all very well but the major benefit of using one or more pulleys/Snatch Blocks Is the it Low gears the speed of the load being moved which allows for a slower more refined recovery, The down side is that it does not give you 3X the pulling Power for a few simple reasons, Using more pulleys is more about precision placement of the load that needs to be moved

1) A 9000Lbs winch and cable is still a 9000Lbs rig So if you add 2 pulleys that is not going to give you 27000Lbs of pulling power because the winch doing the pulling is rated at 9000Lbs and it is Pulling a Single Line and that line goes through those 2 pulleys from the winch to a single Anchor Point from a single cable.

2) the Winch is a single 9000Lbs of pulling power and the Anchor Point is a single 9000Lbs Fixed Point. At this point the weakest links are the 9000Lb Winch and the cable at it's Anchor point.

If a person needs to move a 27000Lb Load then they still need a winch that is rated at 27000Lbs to 30000Lbs or bigger, You can't go putting a 27000Lb Load on a 9000Lb Winch, It does not matter if you use 10 pulleys because it is a 9000Lb winch doing the pulling on a single line to the winch as is the single line Anchor Point the winch cable of a 9000Lb winch is not rated to pull 27000Lbs, By using pulleys all you are doing is low gearing the winch / Travel Speed,

Just because a pulley reduces the speed/Load ratio does not mean you can exceed the Rating of the Winch, this is why the Winch companies tell you to always buy a Winch 2 and a half times bigger that the load that needs to be moved, IE your 6000Lb Truck needs a 15000Lb to 17500Lb (18000) Winch,

IE My Truck/SUV weighs 3990Lbs kerb weight (Empty)
Loaded it weighs 5533Lbs
With a Trailer hooked up fully loaded it can legally weigh 11927Lbs,

So if I am Towing a Camper Trailer etc then my 9500Lb Winch is useless because with just the Truck '5533Lbs @ 9500Lbs minus 5533lbs = 3967Lbs spare, So the correct smallest winch I should be using is 13832Lbs @ 2.5 times the weight of my Truck and the closest winch with that kind of pulling power is a 15000Lbs and if I needed a Winch that can handle the gross vehicle Combination weight then @ 2.5 times that weight then I would need a Winch that is rated for 29820Lbs just to keep within the Winch companies recommendations, which is totally nuts because a winch that powerful would tear the truck in half,

Winching and pulleys etc are a science all by them selves and Pulleys do not half the load all they do is Half the speed of the line pull because the Winch and the Anchor Point still have to deal with the full weight of the Load.

Take a small ratchet and socket and try to remove a lug nut. Take a bigger setup and try to remove it. Now go get a breaker bar and try and then slide a cheater bar on it.

You are still the same person with the same power but because of leverage you can bet more done. Mechanical advantage is the same concept.