16 - Common 4x4 Myths Busted

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4x4 myths

Many 4 wheel drive owners go their whole life without any formal training in going offroad or the vehicles that we use.  Because of this, there are many myths about driving and our vehicles which have crept in over time.

We talk to 4WD expert Robert Pepper about many of these myths, how they came about and why they just aren't correct.

You'll have a better understanding of your car and you'll be a better 4 wheel driver.

We discuss diff locks, recovery techniques, axels and a whole range of other 4 wheel drive myths!

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Latest Posts about 16 - Common 4x4 Myths Busted

Submitted by bigblockford545 bigblockford545
Hope this helps
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Submitted by bigblockford545 bigblockford545
[​IMG] [​IMG]
Submitted by Ali Ozbay Ali Ozbay
Tank
So if the vehicle needs 1000kgs to move it you are saying that it only takes 500kgs. to do so, how much weight is on the rope supporting the SB, Regards Frank.
I'm saying; if the vehicle needs 1000kgs to move it, in the setup below, the winch will have to overcome 500kg plus half the friction loss in the SB.
And the weight on the rope supporting the SB will be 1000, which is the total force to move the car.

Edit Note: I initially said the winch needs to overcome 500 plus the friction. That's incorrect. The correct answer is: 500 plus half the friction as in the revised figure

View attachment 39185View attachment 39192
Submitted by Tank Tank
Ali Ozbay
Frank, as I have repeated many times, the case we're discussing here is a bogged car WITH A WINCH on it and no other rescue vehicles. I understand your case, and you're right in all you say when you recover another car using your winch on your truck. So I believe you misunderstood the scenario we have been discussing. This whole conversation started because you responded to Brett's question, which was about a car recovering itself using a snatch block, in a way that would be true if the car was being recovered by ANOTHER car, as in your daily case.

However, still, you are wrong when you say "Yes you do get a MA using a SB 25' away hooked to a tree, But only because you have more rope out and lower on the drum". You get the mechanical advantage because of the reasons I tried to explain to my best abilities above.

If the bogged vehicle uses a snatch block to recover itself:
1- The total force required to move the car won't be halved (we both agree on this)
2- But the tension in the rope will be halved (you don't agree on this, but it just will. Think about buying 6 bottles of wine and putting them in a single plastic bag. The handles will snap. But if you put them in a second bag, the number of handles will double so the load in each handle will be halved and happy days)
3- The car will start to be pulled from TWO points, on which only half the total force is applied. Two separate points with half of the total recovery load on each. The sum makes (0.5+0.5=1) the total force. So the math still holds.
4- Since the tension in the rope is equal to the force the winch will try to overcome, you can say the recovery capacity of the winch will be doubled by using a snatch block.

Apparently I can't say enough times, so I'm saying again. This holds for the case where a car recovers ITSELF. This does not hold for when a vehicle recovers another vehicle by simply running the rope thru the SB, which is hooked to a tree.

On the other hand, in the case where you run the cable off your truck, attach the SB onto the bogged car and run the cable back to a tree next to your truck is physically very similar to the case where a single car recovers itself with a SB. There is MA in both cases due to the same principle.

Anyway, if you ever have to recover YOUR truck one day, using the winch ON IT, give this a go see what happens.
So if the vehicle needs 1000kgs to move it you are saying that it only takes 500kgs. to do so, how much weight is on the rope supporting the SB, Regards Frank.
Submitted by Ali Ozbay Ali Ozbay
Hi All,

Just to clarify Franks comments which are
"Using a SB to change direction of pull can be extremely dangerous if the triangle formed by anchoring a SB to a tree and pulling another vehicle at an angle, if you have to do this the triangle created will form an Apex at the anchored SB, if that angle is 90 degrees or more you may be doubling the load on the rope/cable and god knows what weight the anchor strap holding the SB to the tree is copping. Always try and keep this angle below 90 degrees, "

Please have a look at the figures below. It is quite easy to misunderstand which angle is which. The term "change in direction of pull" might easily be interpreted differently by different people. So decided to explain with some sketches...

First of all: The force required to free a car from where it's bogged does not vary with the angle of ropes you attached to it or somewhere else. It is constant in each case, as the variable determining the force are mainly, weight of the car, friction between the surface and the car, suction created when pulling and the angle of the slope etc.

Secondly: What you can change by changing the direction of pull is the total force exerted on the SB and the tree. If you look at the diagrams below, you'll see that the maximum load on the SB is achieved when two segments of rope are parallel. As the angle between two segments of rope increase, the total force exerted on the SB decreases. So It is SAFER to make the ANGLE between two segments of rope as LARGE as possible.

Hope this helps


View attachment 39178

View attachment 39179
Submitted by Ali Ozbay Ali Ozbay
Tank
To prove the statements I've made is simple, if you are bogged, instead of grabbing the old Snatch Block (SB) out and hooking it to a tree 25' away, run your cable/rope out 50' away and you will have the same MA as if you had run your rope or cable round a SB 25' away.
I recover broken and bogged 4wd'ers for a living and if I'm on a steep hill that I can't tow up (30% or more) I will position my truck so that when I wind out enough cable to reach the broken 4wd I will only have one layer of cable left on the drum, because this is where the winch pulling power is at it's highest.
Or if I can't get back far enough I attach my SB to the recovery point on the broke 4wd, run my cable down to the SB and back to a tree next to my truck. This way I have a TRUE MA of 2 and I'm pulling to advantage and from the strongest part of the winch's pulling ability.
Yes you do get a MA using a SB 25' away hooked to a tree, But only because you have more rope out and lower on the drum, which I have already explained. Think about it a SB is just a bloody wheel, no magic gears inside to halve loads, because most 4wd'ers believe that a SB halves the bogged load, some commonsense is needed here./
Running a wire cable around a SB also damages the wires, the outer part of the cable is stretched and the inner wires closest to the bottom of the pulley groove get compressed, heavy use of a SB, especially when you can get the same advantage with a straight pull, will cause quicker than usual deterioration of your cable/rope.
Put the popcorn away I have outlined what I've learned over 40 years in the rigging game and what is available in text and technical books and Google an UTUBE what is taught at TAFE rigging courses, make up your own minds, I've said all I'm going to, Regards Frank.
Frank, as I have repeated many times, the case we're discussing here is a bogged car WITH A WINCH on it and no other rescue vehicles. I understand your case, and you're right in all you say when you recover another car using your winch on your truck. So I believe you misunderstood the scenario we have been discussing. This whole conversation started because you responded to Brett's question, which was about a car recovering itself using a snatch block, in a way that would be true if the car was being recovered by ANOTHER car, as in your daily case.

However, still, you are wrong when you say "Yes you do get a MA using a SB 25' away hooked to a tree, But only because you have more rope out and lower on the drum". You get the mechanical advantage because of the reasons I tried to explain to my best abilities above.

If the bogged vehicle uses a snatch block to recover itself:
1- The total force required to move the car won't be halved (we both agree on this)
2- But the tension in the rope will be halved (you don't agree on this, but it just will. Think about buying 6 bottles of wine and putting them in a single plastic bag. The handles will snap. But if you put them in a second bag, the number of handles will double so the load in each handle will be halved and happy days)
3- The car will start to be pulled from TWO points, on which only half the total force is applied. Two separate points with half of the total recovery load on each. The sum makes (0.5+0.5=1) the total force. So the math still holds.
4- Since the tension in the rope is equal to the force the winch will try to overcome, you can say the recovery capacity of the winch will be doubled by using a snatch block.

Apparently I can't say enough times, so I'm saying again. This holds for the case where a car recovers ITSELF. This does not hold for when a vehicle recovers another vehicle by simply running the rope thru the SB, which is hooked to a tree.

On the other hand, in the case where you run the cable off your truck, attach the SB onto the bogged car and run the cable back to a tree next to your truck is physically very similar to the case where a single car recovers itself with a SB. There is MA in both cases due to the same principle.

Anyway, if you ever have to recover YOUR truck one day, using the winch ON IT, give this a go see what happens.
Submitted by Tank Tank
Ali Ozbay
Hi Brett,

If you listen to 38:10 in the podcast, you'll note that he bases his arguement on the case that you don't tether the hook back onto the car being recovered. And he is totally right. If you DONT hook the cable/rope back on to the recovered vehicle, you will NOT gain any mechanical advantage. And you'll end up puling the anchor point (i.e. tree) with a force almost 2 times (at the most, depending on the angle between the two sections of rope i.e. before and after the SB) . However, for this case to take place, the most possible scenario would be that the car being recovered will not have a winch, and another vehicle will recover the car while running the rope thru a snatch block while doing it.
However, as I explained before, as long as the car being recovered has a winch, uses a snatch block AND ATTACHED THE HOOK ONTO ITSELF, there will be mechanical advantage.

This is the difference.

Frank, what do you think?

Cheers,
Ali
To prove the statements I've made is simple, if you are bogged, instead of grabbing the old Snatch Block (SB) out and hooking it to a tree 25' away, run your cable/rope out 50' away and you will have the same MA as if you had run your rope or cable round a SB 25' away.
I recover broken and bogged 4wd'ers for a living and if I'm on a steep hill that I can't tow up (30% or more) I will position my truck so that when I wind out enough cable to reach the broken 4wd I will only have one layer of cable left on the drum, because this is where the winch pulling power is at it's highest.
Or if I can't get back far enough I attach my SB to the recovery point on the broke 4wd, run my cable down to the SB and back to a tree next to my truck. This way I have a TRUE MA of 2 and I'm pulling to advantage and from the strongest part of the winch's pulling ability.
Yes you do get a MA using a SB 25' away hooked to a tree, But only because you have more rope out and lower on the drum, which I have already explained. Think about it a SB is just a bloody wheel, no magic gears inside to halve loads, because most 4wd'ers believe that a SB halves the bogged load, some commonsense is needed here./
Running a wire cable around a SB also damages the wires, the outer part of the cable is stretched and the inner wires closest to the bottom of the pulley groove get compressed, heavy use of a SB, especially when you can get the same advantage with a straight pull, will cause quicker than usual deterioration of your cable/rope.
Put the popcorn away I have outlined what I've learned over 40 years in the rigging game and what is available in text and technical books and Google an UTUBE what is taught at TAFE rigging courses, make up your own minds, I've said all I'm going to, Regards Frank.
Submitted by Ali Ozbay Ali Ozbay
badams
Hi Folks,
Found the talk on snatch blocks a bit confusing.
I always thought part of the benefit was that a snatch block could double the pulling force. If the winch goes out around the snatch block then hooks back to the car, that effectively double the pulling power. See attached.

In my case a winch that isn't really up to the job, so I've always relied on this to make up the short fall.

Brett
Hi Brett,

If you listen to 38:10 in the podcast, you'll note that he bases his arguement on the case that you don't tether the hook back onto the car being recovered. And he is totally right. If you DONT hook the cable/rope back on to the recovered vehicle, you will NOT gain any mechanical advantage. And you'll end up puling the anchor point (i.e. tree) with a force almost 2 times (at the most, depending on the angle between the two sections of rope i.e. before and after the SB) . However, for this case to take place, the most possible scenario would be that the car being recovered will not have a winch, and another vehicle will recover the car while running the rope thru a snatch block while doing it.
However, as I explained before, as long as the car being recovered has a winch, uses a snatch block AND ATTACHED THE HOOK ONTO ITSELF, there will be mechanical advantage.

This is the difference.

Frank, what do you think?

Cheers,
Ali
Submitted by discomatt discomatt
Yep who wants some pop corn, salt AND butter if I remember correctly;)
As far as the discussion I have NFI and would need a set of heavy duty scales to actually test the theories :p
Submitted by hiluxdriver hiluxdriver
cool, a "who's got the biggest d*** " argy bargy. Where's Captain Correction?
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