Lift axles

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
261

Ask Nianiamh… :laughing: :sunglasses:

262

:laughing: :laughing: :laughing: :laughing:

263

bobthedog:
So you drove 6x6s now… But were they artics? Hmm, thought not. :laughing:

I have not been complaining about my truck… Don’t know where you get the idea I have been. I merely said that I would have had more traction in a 4x2 on this trip. You really need to look a little closer… May I suggest Specsavers? (other opticians are available)

End of the day, you are applying your ideas of rigids to artics and, dare I say, drawbars. It doesn’t work the same way at all. I know you think it does, but that merely shows your mind to be somewhat like the railways in the UK… Single track, broken and unreliable…

Now in the real world, we know that 6x4s have their place. We also know that there is room for other configurations which are, in general terms, equally as efficient or more efficient than your beloved 6x4s.

Let me apply some sort of metaphor to this for you. Pushing a wheelbarrow is much easier if you stand on tiptoes than if you push with your feet flat on the floor. The only reason for this must be because tiptoes is like a 4x2 tractor. If you don’t believe me, try it next time they let you work in the asylums garden and you will see I am right… :wink: :laughing: :laughing:

I thought that was the definition of rail transport wherever it is not just here.But no pushing the wheelbarrow,or pulling it in this context,on tiptoes,just means that you’ll probably fall over but I think that’s the test for drunk driving in some American states instead of using a breathalyser.Anyway long story short.Having more driven axles reduces the amount of force required to be applied at each driving wheel to overcome the inertia of the gross weight of a rigid,the combination weight of an artic,or the train weight of a drawbar outfit.Therefore less downforce on those drive wheels/axles is required for the required grip and traction co eficcient.What that means in the real world is that if you compare trucks of whatever comparable weight,in bad traction conditions,regardless of wether it’s grass/mud,snow/ice it’s the thing with more driven wheels which has the advantage.A 4x2 or a 6x2 versus a 6x4 in zb road conditions is like using a knife in a gunfight :laughing: :laughing: .Which is why that Pathfinder is’nt a 6x2 with a zb lift axle :open_mouth: :laughing: :laughing: :laughing: and it’s why Walter Rohrl’s Audi Quattro could blow the doors off of Stig Blomqvist’s front wheel drive Saab in a rally. :laughing: :laughing: :laughing: :laughing: :laughing: :laughing: :laughing:

264

bobthedog:
So you drove 6x6s now… But were they artics? Hmm, thought not. :laughing:

I have not been complaining about my truck… Don’t know where you get the idea I have been. I merely said that I would have had more traction in a 4x2 on this trip. You really need to look a little closer… May I suggest Specsavers? (other opticians are available)

End of the day, you are applying your ideas of rigids to artics and, dare I say, drawbars. It doesn’t work the same way at all. I know you think it does, but that merely shows your mind to be somewhat like the railways in the UK… Single track, broken and unreliable…

Now in the real world, we know that 6x4s have their place. We also know that there is room for other configurations which are, in general terms, equally as efficient or more efficient than your beloved 6x4s.

Let me apply some sort of metaphor to this for you. Pushing a wheelbarrow is much easier if you stand on tiptoes than if you push with your feet flat on the floor. The only reason for this must be because tiptoes is like a 4x2 tractor. If you don’t believe me, try it next time they let you work in the asylums garden and you will see I am right… :wink: :laughing: :laughing:

I don’t know about tiptoes but my old man told me that the only way to push crap uphill was in a wheelbarrow :open_mouth:

265

The mention of Walther Rohrl’s Audi Quattro S1 means that there are indeed moments when the medication does work Crazyfast, that’s a good sign, that car is my all time favorite mechanically propelled object, closely followed by the Ferrari with the two birds in from the Cannonball Run, although the car has SFA to do with my second choice :laughing: :wink:

What you say about overcoming inertia does make sense, it’s a law of physics and they cannot be broken (except by those girls in the Cannonball Run, really they should’ve fallen flat on their faces :laughing: ) but that argument only works on paper, the extra weight you can impose on a single axle once you have lifted the undriven tag, assuming the axle groups are carrying equal weight, will mean that the single drive get’s more traction as the extra weight will push it into the snow/mud/whatever and overcome the need for more turning wheels to provide enough inertia to get moving :open_mouth:

266

newmercman:
The mention of Walther Rohrl’s Audi Quattro S1 means that there are indeed moments when the medication does work Crazyfast, that’s a good sign, that car is my all time favorite mechanically propelled object, closely followed by the Ferrari with the two birds in from the Cannonball Run, although the car has SFA to do with my second choice :laughing: :wink:

What you say about overcoming inertia does make sense, it’s a law of physics and they cannot be broken (except by those girls in the Cannonball Run, really they should’ve fallen flat on their faces :laughing: ) but that argument only works on paper, the extra weight you can impose on a single axle once you have lifted the undriven tag, assuming the axle groups are carrying equal weight, will mean that the single drive get’s more traction as the extra weight will push it into the snow/mud/whatever and overcome the need for more turning wheels to provide enough inertia to get moving :open_mouth:

The quattro is great on slippery road surfaces but sometimes in a perfect world on dry perfect roads you can’t beat 2 wheel drive. :open_mouth:.But you’ve just done what btd said.You’ve shot your own argument.Yes lifting a tag will just push a single drive axle deeper into the zb and it will put the drive axle overweight.Which is how that Pathfinder climbed that hill because it had less axle weights but more driven axles that’s the real world not paper.But were’nt those birds in the Cannonball run using a Lambo :question: And guess what still holds the record for the last time they actually ran it in anger :smiley: It’s a V12 with 2 wheel drive and it’s British. :smiley:

youtube.com/watch?v=c5jtf83eKGs

267

Lambo, Ferrari, who was looking at the car :laughing: :laughing: I thought it was a 308 though as it had no roof :sunglasses:

Not shot myself down though, my pushing down is pushing me down to the tarmac, not further into the doo doo, I’m a highway driver, if I don’t have tarmac under my wheels then it’s all gone horribly wrong already :open_mouth: :laughing:

I agree about the rwd drive cars, mine is rwd & is so much fun with the T/C disengaged, which is all the time, every journey is like a rally stage :sunglasses: :laughing:

268

Just done a test with lego truck move kingpin foward is tighter turn

269

Carryfast:

newmercman:
The mention of Walther Rohrl’s Audi Quattro S1 means that there are indeed moments when the medication does work Crazyfast, that’s a good sign, that car is my all time favorite mechanically propelled object, closely followed by the Ferrari with the two birds in from the Cannonball Run, although the car has SFA to do with my second choice :laughing: :wink:

What you say about overcoming inertia does make sense, it’s a law of physics and they cannot be broken (except by those girls in the Cannonball Run, really they should’ve fallen flat on their faces :laughing: ) but that argument only works on paper, the extra weight you can impose on a single axle once you have lifted the undriven tag, assuming the axle groups are carrying equal weight, will mean that the single drive get’s more traction as the extra weight will push it into the snow/mud/whatever and overcome the need for more turning wheels to provide enough inertia to get moving :open_mouth:

The quattro is great on slippery road surfaces but sometimes in a perfect world on dry perfect roads you can’t beat 2 wheel drive. :open_mouth:.But you’ve just done what btd said.You’ve shot your own argument.Yes lifting a tag will just push a single drive axle deeper into the zb and it will put the drive axle overweight.Which is how that Pathfinder climbed that hill because it had less axle weights but more driven axles that’s the real world not paper.But were’nt those birds in the Cannonball run using a Lambo :question: And guess what still holds the record for the last time they actually ran it in anger :smiley: It’s a V12 with 2 wheel drive and it’s British. :smiley:
Jesus after all this time you cant beat two wheel drive in perfect conditions which is what most of us have most of the time so all this double drive nonsense is over the top for most of us. And my double drive artic has spent most of its off road time today chained to the back of a D8 so when its ■■■■ conditions you need tracks not wheels.
youtube.com/watch?v=c5jtf83eKGs

270

If we are talking cars il have an audi rs4 please.
Do the american truck makers offer an alternative to double drive on there heavyweight tractors. Or is it a case of thats it take it or leave it.

271

newmercman:
Lambo, Ferrari, who was looking at the car :laughing: :laughing: I thought it was a 308 though as it had no roof :sunglasses:

Not shot myself down though, my pushing down is pushing me down to the tarmac, not further into the doo doo, I’m a highway driver, if I don’t have tarmac under my wheels then it’s all gone horribly wrong already :open_mouth: :laughing:

I agree about the rwd drive cars, mine is rwd & is so much fun with the T/C disengaged, which is all the time, every journey is like a rally stage :sunglasses: :laughing:

Now we are all back on the same stage, the roar of a fully wound up Lancia Stratos is like having solo ■■■ :laughing:

272

newmercman:
Lambo, Ferrari, who was looking at the car :laughing: :laughing: I thought it was a 308 though as it had no roof :sunglasses:

Not shot myself down though, my pushing down is pushing me down to the tarmac, not further into the doo doo, I’m a highway driver, if I don’t have tarmac under my wheels then it’s all gone horribly wrong already :open_mouth: :laughing:

I agree about the rwd drive cars, mine is rwd & is so much fun with the T/C disengaged, which is all the time, every journey is like a rally stage :sunglasses: :laughing:

308 :open_mouth: .Ferraris should be like the Jag V12 front engine rwd but don’t even know what T/C is just an uprated lsd and around 400 lbs/ft of torque and over 350 bhp on webers :open_mouth: :smiley: so I’ll just leave it in the garage until winter’s over and the roads are dry.

But established (good) engineering practice,and axle weight limits say that you’re not going to be able to put enough weight on that tarmac (that would have been under your wheels on a dry summer day) to compensate for the loss of traction co efficient,caused by the ice and snow that’s between them and the road,in conditions like btd described.But all previous real world engineering experience says that using more drive axles,instead of more weight,is the best way to compensate for that problem and is the best way of solving the traction versus inertia problem.The real world figures say that the reduction in the forces applied at the wheels,using more drive axles,to overcome the inertia of the load to be moved,outweighs the gain in traction of using half the amount of driving wheels with more weight on them especially when the inherent compromise which the load deck of a semi trailer relative to tractor unit drive axle weights versus it’s total combination weight are factored into the equation.Which is why for shifting a lot of weight you still can’t beat the 6x4,sometimes even 8x6,ballast tractor and drawbar trailer idea and for all the rest it’s 6x4 for artic tractor units and 6x4 or 8x4 for rigids and drawbar prime movers :smiley: .That’s until the economists and fuel taxation supporting zb’s throw a spanner in the works :frowning: :imp: :unamused: .

273

Well just to add fuel to the fire, i agree with Carryfast.
I would not swap my 6X4 for any single drive tractor. It is properly spec’d with both cross locks and full locking diffs and will pull absolutely anywhere.
I have only once had to use chains and even then i just put a pair of singles on the rearmost axle.
Yesterday it was in the minus 20 degc and i was holding the truck back on long gradients with the Jake brake on number 3. Try doing that with a 6X2 and see how far you get before you lock the drive up and slide off the highway.
It is pointless to talk of 6X2 configurations with lift axles over here because a set of tandem axles would only be legal to transfer weight across to a maximum of 20,000lb on the heaviest axle leaving 14,000lb trailing on the ground on the undriven axle. What good would that be?
In short, the trucks over here have evolved to suit the conditions and regulations that exist over here and the trucks in Europe have evolved to suit the conditions and regulations in Euroland.
It is true that Messila Valley Transport have been experimenting with 6X2 tractors but they also have those silly wheel covers over their back wheels to disguise the hub ends so that nobody takes the ■■■■ out of them in truckstops, Ha ha…
Some might say that double drive is over specified for longhaul but whats wrong with over spec’ing things anyway? It has got to be better than under specifiying stuff. Certainly from the drivers point of view anyway.

274

Carryfast
Why is traction such a big concern to you? no one here has a problem with 6x2 4x2 etc 99% of the time. What are you trying to solve ? Running trucks fuel consumption is the main issue and nothing supps fuel like a double drive back end, well nothing apart from a detroit, who can afford to run these mythical beasts?

275

Trev_H:
Carryfast
Why is traction such a big concern to you? no one here has a problem with 6x2 4x2 etc 99% of the time. What are you trying to solve ? Running trucks fuel consumption is the main issue and nothing supps fuel like a double drive back end, well nothing apart from a detroit, who can afford to run these mythical beasts?

It all depends on your definition of 99% of the time.That’s just based on a period of some relatively easy winter periods which have’nt always been the case.Which is why many of the older drivers,who’d remember driving in the 1950’s and 1960’s,and even some of the conditions which were common in the 1980’s which I can remember,would agree with my ideas.But sometimes it’s not good engineering practice to base design on the lowest common denominator concerning fuel consumption.But even the yanks know that the old detroit two stroke fuel consumption issues (and the older generation four strokes like CAT 3406 AND 3408) were unsustainable even at their prices so that’s irrelevant.I’m not trying to solve anything but I do understand the difference between good and compromised engineering and that’s what I’m pointing out.

276

wire:
Well just to add fuel to the fire, i agree with Carryfast.
I would not swap my 6X4 for any single drive tractor. It is properly spec’d with both cross locks and full locking diffs and will pull absolutely anywhere.
I have only once had to use chains and even then i just put a pair of singles on the rearmost axle.
Yesterday it was in the minus 20 degc and i was holding the truck back on long gradients with the Jake brake on number 3. Try doing that with a 6X2 and see how far you get before you lock the drive up and slide off the highway.
It is pointless to talk of 6X2 configurations with lift axles over here because a set of tandem axles would only be legal to transfer weight across to a maximum of 20,000lb on the heaviest axle leaving 14,000lb trailing on the ground on the undriven axle. What good would that be?
In short, the trucks over here have evolved to suit the conditions and regulations that exist over here and the trucks in Europe have evolved to suit the conditions and regulations in Euroland.

All of the drawbacks concerning single drive axles apply just the same here in bad conditions and ice is ice and snow is snow wether it’s 20 below or just 2 degrees below freezing.The issue seems to be that european drivers will put up with anything and the government would prefer to tax fuel at the expense of flawed truck engineering.

277

Wire, you vanish for months then come back and take mr nutters side? :cry:

OK, now here is something to consider… If you have your traction tyres then you would not lock the axle up as much if it has 10 tonnes pushing on it as opposed to 6 tonnes. Having the weight on the compacted snow will, at -20, break the damned stuff off the road anyway.

I would try it. You arrange a 4x2 or 6x2 for me and we can try the challenge out. Rogers Pass will do it. I will let you know how it is there tomorrow… :laughing:

278

I promised Curryfart some pictures, didn’t I…

Compacted snow on Vancouver Island… Pretty rough going.

These are what I was carrying… This one actually started!!

See, double decked… 5 tonnes in all. Of course, I had 3 bottom ramps and only 1 top ramp, so I had to improvise… :laughing:

279

bobthedog:
Wire, you vanish for months then come back and take mr nutters side? :cry:

OK, now here is something to consider… If you have your traction tyres then you would not lock the axle up as much if it has 10 tonnes pushing on it as opposed to 6 tonnes. Having the weight on the compacted snow will, at -20, break the damned stuff off the road anyway.

I would try it. You arrange a 4x2 or 6x2 for me and we can try the challenge out. Rogers Pass will do it. I will let you know how it is there tomorrow… :laughing:

You’re trying to transmit the same amount of engine braking versus the same amount of forward inertia with half as much contact between drive wheels and road.If it’s fully freighted you can transmit a lot more engine braking force to the ground,versus GCW,with the total axle weights and the grip coefficients provided by 2 drive axles and double the amount of drive wheels,than just one and the advantage applies pro rata until the GCW,and therefore drive axle weights,are low enough not to need much engine braking anyway.

280

You really have no idea, do you…