winch brain teaser question

heres one: say a winch is rated at 9000 lbs. now i know it can't generate 9000 lbs of actual pull force,(like a vertical hoist lifting 9000 lbs. off the ground) but it is designed to pull less than 9000 <rolling> lbs out of a ditch. clearly not the same load. so the question is what would be the actual <roundabout> amount of maximum force (in lbs, tons, etc.) that this winch could exert on a load? ok. also for a 5000 or 12000 lb. winch. is there some type of simple formula for this? :dunno:

I thought 9000lbs was 9000lbs?
pound of feathers=pound of lead

if its a dead weight pull, doesnt matter the direction. But if the object you're pulling is moving in the opposite direction then yea it will matter.

For every 15* of angle upwards add 25% to the loaded weight of the object (and this is IF there's no additional resistance). By the time you get to 90*, you're looking at 150% of the object's weight (I believe due to gravity, but don't quote me here).
Great information here: http://www.pirate4x4.com/tech/billavista/Recovery/index.html

xuv-this said:

heres one: say a winch is rated at 9000 lbs. now i know it can't generate 9000 lbs of actual pull force,(like a vertical hoist lifting 9000 lbs. off the ground) but it is designed to pull less than 9000 <rolling> lbs out of a ditch. clearly not the same load. so the question is what would be the actual <roundabout> amount of maximum force (in lbs, tons, etc.) that this winch could exert on a load? ok. also for a 5000 or 12000 lb. winch. is there some type of simple formula for this? :dunno:

Click to expand...

Read teh section about calculating the force:
http://www.pirate4x4.com/tech/billavista/Recovery/index.html

Timber said:

For every 15* of angle upwards add 25% to the loaded weight of the object (and this is IF there's no additional resistance). By the time you get to 90*, you're looking at 150% of the object's weight (I believe due to gravity, but don't quote me here).
Great information here: http://www.pirate4x4.com/tech/billavista/Recovery/index.html

Click to expand...

Talk about timing

lifting 9000 lbs straight up is lifting 9000 lbs straight up. if 9000 lbs is sitting on wheels (such as a vehicle) on flat ground in neutral, there is a formula to determine the actual weight being pulled. you have to factor in the resistence from the ground on the tires and the actual weight of the vehicle. but i do know its not the same. pulling 9000 lbs on wheels on flat ground requires much less force than lifting 9000 lbs of dead weight straight up.

this thread is funny

Timber said:

For every 15* of angle upwards add 25% to the loaded weight of the object (and this is IF there's no additional resistance). By the time you get to 90*, you're looking at 150% of the object's weight (I believe due to gravity, but don't quote me here).
Great information here: http://www.pirate4x4.com/tech/billavista/Recovery/index.html

Click to expand...

Wow!
So I weigh more when standing on a slope then I do hanging from a rope.
Hey I'm a poet and I didn't even know it.

There's something horribly, horribly wrong with this math.
As in it's completely wrong.
For pulling a load up a slope you use Sin(slope angle in degrees)*Dead Weight Load + rolling resistance.
Sin(slope) will ALWAYS < 1.0, so it can never be equal to an amount greater than the dead weight load itself. The sin(90) {ie; a vertical 'slope'} is equal to 1.0.
Rolling resistance is also a function of the dead weight load, slope and some impossible to determine coefficient of friction.
Normally friction factors are less than 1.0, but the impossible to determine coefficient of friction for being hopelessly stuck in mud could 'effectively' exceed 1.0 resulting in the "friction" component of the equation actually exceeding the vehicle weight.

Of course all of this is foolishly academic and pointlessly worthless.
Bottom line is a 9000 lb winch can pull, drag, lift, hoist, yank, suck or tug 9000lbs. How you achieve that 9000lbs is up to you, but it weighs the same no matter what.

A winch rating implies it's maximum load rating just prior to stall on the last full wrap of cable on the spool. For each additional layer of cable wrap on the spool, the max load to stall decreases.

I thought a 9000lb. winch was rated for 9000lbs. - provided you're on the first layer of the spool. That number drops considerably depending upon how many layers of cable are on the spool.
Forget calculating the force needed to pull a vehicle on it's wheels, what's needed most is the force needed to pull that vehicle out of mud once it sitting on it's axle's

olivedrabcj7 said:

lifting 9000 lbs straight up is lifting 9000 lbs straight up. if 9000 lbs is sitting on wheels (such as a vehicle) on flat ground in neutral, there is a formula to determine the actual weight being pulled. you have to factor in the resistence from the ground on the tires and the actual weight of the vehicle. but i do know its not the same. pulling 9000 lbs on wheels on flat ground requires much less force than lifting 9000 lbs of dead weight straight up.

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that's my point. the question is though, i guess more specifically; what is the (winch)industry standard for the amount of resistance they use to determine the load for that 9000 lb winch? aka in real world terms: is the <9000 lb vehicle that it is rated for on a 10% grade/slope,3 ft of mud, etc. if i knew what the resistance factor/angle was, i could do the trig for a vertical load.

what do you mean the "standard for the amount of resistance they use to determine the load for that 9000 lb winch?"

9000lbs is 9000lbs, period

if you are pulling a normal rolling vehicle on flat pavement it only requires force equal to about 10% of the vehicles weight, if it's grass or dirt it's about 33% of the weight to move it (notice how you can push a car off the road? did you really think you were exerting thousands of lbs of force?)

if you are on a slope you are simply adding 25% for every 15degrees to the 10% (paved) or 33% (dirt), provided you are pulling a vehicle that still rolls.... you are not pulling full vehicle weight+ additional percentage for slope unless you have 4 locked up brakes

and if you lift something in the air (hoist) then vehicle weight is simply vehicle weight

oh and unless you are buying a HF winch the 9000lb rating is for single line dead pull, no snatch blocks or extra pulleys that give mechanical advantages/reductions

DaveD912 said:

I thought a 9000lb. winch was rated for 9000lbs. - provided you're on the first layer of the spool. That number drops considerably depending upon how many layers of cable are on the spool.
Forget calculating the force needed to pull a vehicle on it's wheels, what's needed most is the force needed to pull that vehicle out of mud once it sitting on it's axle's

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a point i forgot. the math can also be done for the outer/last laver on the spool, provided that the initial force on the innermost layer is known. i take a statics class, and we had some winch problems. it occured to me that the loads a lot of us use on our winches can easily multiply to far greater than most would expect. and hence arose my question.

Did either of you listen to a thing I said?



:Sheesh: What in the world is wrong with kids these days? :lecture:

This is really not that complicated your 9000lbs winch will provide you with 9000lbs of line tension. If that is enough to get you unstuck your good. If it’s not your winch will stall.

So if your 4000lbs rig is on flat, hard ground and you want to move it with the winch your in good shape. If your rig is buried in texas mud from the top of the hood down or sitting behind a 2,00,000 lbs rock on the trail, it ant gona do it. What possible good will it do to bust out the trig when you have no way of knowing the variables that will be present for any given pull.

This thread is kinda funny.

I saw a guy with 12000lbs winch on a little light buggy get that thing buried up well past the top of his 38s in the snow that there was no way his winch was doing him any good till he moved a LOT of snow.

In conclusion buy the best winch you can and try not to get too stuck before you thing to use it.

C-ROK said:

Did either of you listen to a thing I said?

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i understand what you said. i coulda sworn that they weren't rated to the same standard of pull that vertically rated winches are... yes i know that vertical winches are designed diffrently, and recovery winches aern't to be used for vertical use; when i first got my 9000 a couple years back, 5 or 6 people told me that it they are rated that to a certain angle. like in winch catalogs they tell you to add 10-15% to the trucks actual expected weight for a safe-zone, because it is rated for an angle, not vertically pulling that weight....or am i totally wrong???

here was some interesting pysics work - for an XJ stuck on flat asphalt road:

http://www.naxja.org/forum/showthread.php?t=44742&highlight=pull

Tension in the line at an angle is more than a straight pull - but the body doesnt weigh more...

draw a free body diagram showing all the forces and add them up...

ok. sorry for the stupid Question :dunce: guess i was told wrong...

XJ_ranger said:

here was some interesting pysics work - for an XJ stuck on flat asphalt road:

http://www.naxja.org/forum/showthread.php?t=44742&highlight=pull

Tension in the line at an angle is more than a straight pull - but the body doesnt weigh more...

draw a free body diagram showing all the forces and add them up...

Click to expand...

i understand the physics, i was just under the beleif that the lb rating was different.:dunce:

when i bought my winch, i decided i didn't want to deal with the BS of all of this and went with a 12000 lb.