Does this system reduce friction over a more simple set up that might achieve the same theoretical advantage?

The 5:1 shown will surely get the tire to the top - and without retying anything. Simply haul until the pulley on the blue rope gets to one end of the rope, reset the prusik on the main line, and haul again.

Sorry, ain't gonna happen.

You see, majid has forgotten his progress capture device on the red pulley of the green rope, so he'll merely be lifting the weight up and lowering it back down with the system he has designed here. Perhaps such was his intention, however, IDK.

With inefficiencies inherent with pulley hauling systems, I'll guess about 65-70ish pounds of upward force will be exerted by the sorry sucker at the top of the line. The fact that the hauler is not wearing a helmet means that an asteroid will certainly fall fall from the sky striking his noggin and knocking him unconscious, causing the load to fall abruptly to the ground from whatever height it had been raised to, thereby crushing and killing someone in the middle of an attempt to attach a truck to the tire.

I would not identify myself as a noob, but I have no idea what is going on there.

That's why I: a. do not do anything that involves hauling (or pooping in a bag and saving it).
b. do not get in accidents/fall in crevasses/ have a partner do same, and have to self-rescue.

You do not need to hide it, just say you only do bouldering

hah... I stand corrected.

Is it ironic that I'm sitting in a tire shop getting new tires put on my truck?

One thing to keep in mind with this system is that one of the pulleys endures twice the load of the other two pulleys (80% of the weight of the tire). If you have pulleys of different strengths, choose their locations wisely.

Um, I'm thinking along a different set...

The first red pulley above the tire would experience 200% of the weight of the tire, no? 100% of the initial weight, plus the 100% necessary on the other side to perform the lift.

Am I totally off with that line of thinking? If pulley strength were a consideration, I'd definitely put the strongest one in the position mentioned above. Hopefully it has the largest sheave, too.

See the attached photo. Here's my logic...



Assume you're pulling with tension T at point (A).
Assume the pulleys are frictionless.
Assume the system is loaded, but static (not accelerating or moving).

The red circles are pulleys.
The blue and green lines are ropes.
The blue line at pulley 2 is attached to the anchor, not the pulley.

If the tension at point (A) is T, then the tension at points (B) and (C) must also be T.

For equillibrium at pulley 1, the tension in the blue rope at point (F) must be 2T. Therefore the tension at point (E) must also be 2T.

For equillibrium at pulley 3, the tension at point (G) must be 4T.

The tension, then, at the load (H) must be the sum of (G) and (C) which is 5T - hence the 5:1 mechanical advantage.

If we look at the tensions in the lines, pulleys 1 and 2 endure 2T, or 2/5ths of the load. Pulley 3 must endure 4T, or 4/5ths of the load.

Trenchdigger

Nice analysis and stymingersfink nice sharp eye.

Majid, you really need to stop calling these people here n00bs.

I noted in your explanation that the blue rope labeled (E) was attached to the anchor itself, not the pulley (2). A key point in your equation when considering pulley strengths (i believe?).

However, in your summary the sum of the tension forces felt by the pulleys totals 6/5ths the load. Can you explain this a little more for me?

Yah, basically. Otherwise that pulley's attach point to the anchor would take 4T of load. Also, your average pulley doesn't have an attach point on both ends (though some do).

I don't think it really matters (it would actually be 8T rather than 6T, making the pulley totals 8/5ths of the load). I don't know without thinking about this more, but it may tell you something else useful about the system. Or it may not

You do not need to hide it, just say you only do bouldering

I don't think it really matters (it would actually be 8T rather than 6T, making the pulley totals 8/5ths of the load). I don't know without thinking about this more, but it may tell you something else useful about the system. Or it may not

There's gotta be something I'm missing here... at least, that's what my understanding of the law of conservation of energy is telling me. WTF?

Is the extra 3/5ths lost as inefficiency within the system?

There's something wrong here... the pulley system, as a total, should only experience 5/5ths the mass of the load, plus perhaps a small percentage of efficiency lost as friction within the system. I'm finding it hard to believe that 3/5ths the load, or 180lbs of tension, is added due to inefficiency within the system.

Tranch

Draw me a 5:1 closed system

I hope you know how to do it without google.

Major Sorbet

If we assume the pulleys are 100% efficient (or if we included a bunch of complicated friction and thermodynamic calculations), then this is a closed system.

Do you know the definition of a "closed system" without Googling it?

Did you possibly mean a simple 5:1 system?

5:1 close system is generally simpler than what I have up there so yes you can call it simple 5:1

No google search is allowed

Also do the math on those angle and tell me if OP is actually a 5:1 .

it should be near 4:1 + -

move it move it move it

You know

All this number crunching is for nerds and geeks. In real world applications out in the field if you can't pull the load add more mechanical advantage. That's what we do. Improvision is the key.

Not that professor know it all stands there and starts crunching numbers and theories. Waste of time, as the patient and rescuer has to to be raised and time is of critical importance.

Just like in war, some guy is shooting at ya. Some West Point nerd will say this bullet is traveling at such and such velocity and has this particular bore carries such and such ammo and blah blah blah.

Meanwhile .........

You still don't know what a closed system is. I'll even change the rules - you can google it.

Do you even know the definition of a simple pulley system?

Obviously, not enough information is given to calculate anything.

You got an F for not answering my questions

You know

All this number crunching is for nerds and geeks. In real world applications out in the field if you can't pull the load add more mechanical advantage. That's what we do. Improvision is the key.

Not that professor know it all stands there and starts crunching numbers and theories. Waste of time, as the patient and rescuer has to to be raised and time is of critical importance.

Just like in war, some guy is shooting at ya. Some West Point nerd will say this bullet is traveling at such and such velocity and has this particular bore carries such and such ammo and blah blah blah.

Meanwhile .........

what is the MA on this one ?

[[URL=http://www.imagehosting.com] [IMG]http://www.imagehosting.com/out.php/i1001328_untitled.JPG[/IMG]

4:1

Trench

What is this?

Simple
Complex
Compound

[URL=http://imageshack.us][IMG]http://img215.imageshack.us/img215/2307/untitledgs8.jpg[/IMG]

Try again...

I'll give you a clue: It's a trick question.

Try again...

I'll give you a clue: It's a trick question.

I think you are in a wrong post. trench is playing poker with me showing his cards but he has no cash to win this

1) Define "closed system" as it pertains to hauling systems.

2) Define simple, complex, and compound as they pertain to hauling systems.

3) Which of the 5:1 systems in this thread is more efficient? The simple system shown here, or your illustrated complex 5:1 system?

BONUS) Show me a COMPLEX 7:1 MA hauling system.

Just try answering one of the three, Major Sorbet.

I am not a rigger, You need to ask Rasoy all these question.

Trick question? What 2:1 or is it that since the diagram doesn't accurately show the top pulley in a fixed position, does the whole thing fall apart?

top pulley is fixed to anchor
all other pulleys are moving
so what is the MA ?

1) Define "closed system" as it pertains to hauling systems.

2) Define simple, complex, and compound as they pertain to hauling systems.

3) Which of the 5:1 systems in this thread is more efficient? The simple system shown here, or your illustrated complex 5:1 system?

BONUS) Show me a COMPLEX 7:1 MA hauling system.

I'll try it, compound 6:1

Am I right???
Binrat

Binrat

just quietly delete your post before any one else see it.
it does not look good

OK I'll give him (Majid) help for 2)

Simple Pulley Systems

Basically one continuous rope flowing between the pulleys.

Tension in the rope remains the same throughout in the simple pulley system.

Compound

1 simple pulley system pulling another simple pulley system. The advantage being greater MA for the same number of pulleys in simple system thus reducing overall loss due to friction.

Complex

Are basically neither simple nor compound. Thats why they're complex

aren't we allowed to make mistakes? Stop being haughty, please.

Tom
you are allowed to make mistakes but not BINRAT. He falls in to a different catogory where he can not effort of making any mistakes.

trench

You see , no matter who answers you , you still need to re correct it and modify it so it could please you. This is why I try not to answer or create additional conflicts.

Tom
you are allowed to make mistakes but not BINRAT. He falls in to a different catogory where he can not effort of making any mistakes.

Emphasis my own...

Quoted for posterity.

No surprise. The biggest troll on rcdotcom will not bite the bait on anyone else's line!

I certainly won't let Majid off the line by answering any of the questions for him, but while I'm posting, here's my answer to one of his. This is fun!

In this system, we do seem to have a problem:

[IMG]http://i10.tinypic.com/4ztflt0.jpg[/IMG]

The problem is that this is a single continuous line, so all the parts of it should have the same tension. But the part I've marked ?X is being expected to hold twice the force that the tension in it can hold. I don't know what would happen, but I imagine that the first pulley would not be held down by that line, and would just fly up to the top pulley. Am I right?

GO

Trying to be the smartest guy here does not help others nor makes for a good learning experience.

It will just turn people off and they'll go else where?

My God's dick is bigger than your God's dick!

In this system, we do seem to have a problem:

[IMG]http://i10.tinypic.com/4ztflt0.jpg[/IMG]

The problem is that this is a single continuous line, so all the parts of it should have the same tension. But the part I've marked ?X is being expected to hold twice the force that the tension in it can hold. I don't know what would happen, but I imagine that the first pulley would not be held down by that line, and would just fly up to the top pulley. Am I right?

GO

Ok, I just set this up just using carabiners because I don't have pulleys. When I pulled up on the rope there was too much friction on the top pulley giving only the use of the lower 2 for a MA of 4:1. If i pulled horizontally away from the system making less friction the rope would pass through all of the pulley, so this could actually work.. When I picture this I see it as the top pulley lowers the MA because it increases the rate that the load will rise. So if I'm seeing this right my third and final guesstamation is 3:1.

So another answer from the noob MA is 3:1??

[URL=http://imageshack.us][/image]
Assuming all ropes are in straight line. if tire weights 300 lbs, how much weight Joe is pulling ?

LOL

Yeah maybe on paper he's pulling 67.87 pounds.

In the real world there's always way more friction that will slow you down and make you put "One more man on the pull team."

When those lines start going over the edge you'll see what I'm talking about.

LOL

Yeah maybe on paper he's pulling 67.87 pounds.

In the real world there's always way more friction that will slow you down and make you put "One more man on the pull team."

When those lines start going over the edge you'll see what I'm talking about.