Lift axles

[phil_the_book]

Carryfast:

phil the book:

Carryfast:

switchlogic:
Oh wow Carryfast, you’ve surpassed yourself! I didn’t bring up climate change because this isn’t the time or place for a long debate but I really didn’t think I’d ever meet someone who denies the oil is running out! Are you some mad genius who’s found an infinite supply of oil under his living room? I admire your perseverance in this argument but I’m gonna give up on this post now as your really are a complete loon!

Just out of interest, for someone who is so obviously obsessed with the inferior technology in North America why don’t you live there? You strike me as someone who say a lot and does little.

It’s lucky that they did’nt believe that the oil is running out at Airbus either when they decided to fit that zb great big plane of theirs with four engines instead of just two when one of those engines blew up the other day while it was climbing and that did’nt seem to be thought of when they built Terminal 4 at Heathrow to take all the extra plane passengers based on the future growth in air transport all based on tax free fuel. But I was thinking of emigrating to North America but when I wanted to go they would’nt let Brits in,probably because they thought that all Brits are raving green nutters , and it’s too late now.But it would have been a lot easier if I’d have been born a yank instead of a Brit.

It would have been better for all of us if you had been born a Martain.

But the yanks decided that four wheel drive was still better even on the moon where the gravity is even less than on Mars when they built the Lunar rover .

Perhaps they made it 4 wheel drive for all the gritting they may have to do?

[wheel_nut]

phil the book:
Perhaps they made it 4 wheel drive for all the gritting they may have to do?

I know the perfect driver for it, he is already living on another planet

[bobthedog]

The “yanks” also invented snowboarding… Not all their ideas are that good, crazyfit.

Besides, do you really believe they went to the moon? I reckon that was one of Spielbergs early movies…

[carryfast]

bobthedog:

Carryfast:
The fact is a fully freighted artic will fry it’s brakes going down a zb great long down grade in zb weather just the same as in the summer.So why bother with fitting a jake or whatever type of engine braking magnification equipment if you want to turn the thing off right at the time when you most need it. And under btd’s logic newmercman would also throw the back brakes away on his beast as well as turning off the T/C because in most situations the front wheels are loaded up to around twice as much under braking as the rears.I might try the same idea on the Jag too but if it locks it’s front wheels up and wipes out Fritz’s Trabant trying to slow nearly 2 tonnes down from 160 mph on the autobahn I’ll just tell the law that it seemed like a good idea at the time when I factored in the extra weight on the front wheels under braking at that speed. But in this case we’re throwing even more braking effort away because on a double drive bogie the weights on both drive axles are about equal.

Erm, hang on a minute… Why have you dragged me into this one?

Now, regarding your point about the weight on the front axle… Well actually, you are wrong yet again. See, these units are long enough that the weight on the steers is fairly constant at 12000 lbs or so. We don’t tend to get the same problems as euro spec trucks because we use short necked trailers and they are a long way behind the steers.

As to your continued protestations that more than one wheel is driving at any given time, we do not have 1983 2.8 injection LS diffs, we have heavy Rockwells. So your BS about coefficients is just that… BS. I have 13.5 tonnes on the front and 13.2 on the trailer bogie. My steers are showing 5.2 tonnes/ So if we follow your theory about even weight distribution, then each one of my drive wheels has a mere 3.4 tonnes bearing on it. With that in mind, and considering that the power divider is little more than a diff, I only ever have 3.4 tonnes being driven. With a single drive axle, I would have considerably more, would’t I? If the one axle is loaded to a max of 10.5tonnes then I would have 5.25 tonnes being driven… Pure mathematics.

You’ve got to get the context before you start throwing figures into the equation .The reference to newmercman’s steer axle on his car under braking was ‘only’ meant as a ‘comparison’ and an ‘analogy’ to show that extra weight on one axle won’t compensate for having traction and braking forces transmitted through a relatively more lightly loaded one in addition to the heavy one or,even better,in the context of a 6x4 tractor unit,versus a 6x2,it’s ‘two’ ‘evenly loaded’ (but individually lighter loaded),drive axles versus one relatively heavier loaded drive axle and one relatively lighter loaded undriven axle.What you’ve actaully got is ‘two’ drive axles loaded at up to a maximum of 17,000lbs ‘each’ versus ‘one’ drive axle loaded at up to 20,000 lbs and one useless undriven one loaded at up to a maximum of 14,000lbs .What you’ve effectively,actually,got with the 6x4,is the equivalent of a 4x2 tractor unit,with it’s drive axle loaded at up to a maximum of 34,000lbs.However with the 6x4 that load is spread out in way in which there’s less individual weight on each driving wheel,to stop the roads being shattered,and in which the tractive forces and engine braking forces which have to be applied to the road,are shared out among more wheels,so there’s more contact area between drive wheels and road and each wheel doe’s’nt have to apply so much force on the road to overcome the inertia of the load of the combination weight of the truck,so each wheel is more likely to hold on before it loses grip.Pure mathematics.

[carryfast]

newmercman:
the only way that it would be safe out there tonight is in a tracked vehicle and preferably one that was armour plated too, that Crazyfreak is what we encounter here, it’s either ok to drive, or it’s time to park it up, there’s no middle ground, no matter how many wheels go round when you step on the gas

In that case maybe it would be better to take that gas axe to the bonnet of wire’s Pete and turn it into a cab over drawbar prime mover and bring it over here where one of those typical euro heaps has brought the A1 to a standstill in a few inches of snow and you can start an import company over there for all of those 6x2 euro heaps and turn the yank haulage industry into a goldmine.

[carryfast]

newmercman:

Carryfast:

phil the book:

Carryfast:

switchlogic:
Oh wow Carryfast, you’ve surpassed yourself! I didn’t bring up climate change because this isn’t the time or place for a long debate but I really didn’t think I’d ever meet someone who denies the oil is running out! Are you some mad genius who’s found an infinite supply of oil under his living room? I admire your perseverance in this argument but I’m gonna give up on this post now as your really are a complete loon!

Just out of interest, for someone who is so obviously obsessed with the inferior technology in North America why don’t you live there? You strike me as someone who say a lot and does little.

It’s lucky that they did’nt believe that the oil is running out at Airbus either when they decided to fit that zb great big plane of theirs with four engines instead of just two when one of those engines blew up the other day while it was climbing and that did’nt seem to be thought of when they built Terminal 4 at Heathrow to take all the extra plane passengers based on the future growth in air transport all based on tax free fuel. But I was thinking of emigrating to North America but when I wanted to go they would’nt let Brits in,probably because they thought that all Brits are raving green nutters , and it’s too late now.But it would have been a lot easier if I’d have been born a yank instead of a Brit.

It would have been better for all of us if you had been born a Martain.

But the yanks decided that four wheel drive was still better even on the moon where the gravity is even less than on Mars when they built the Lunar rover .

This gets my vote as the best response on this whole thread, PMSL

Actually it was just that all of the combined brains at NASA came to the conclusion that having more driven wheels and less axle weights is the best way to overcome the inertia of the vehicle’s gross mass.Because even in a place where it’s almost weightless the mass and therefore the inertia stay the same

[carryfast]

bobthedog:
The “yanks” also invented snowboarding… Not all their ideas are that good, crazyfit.

Besides, do you really believe they went to the moon? I reckon that was one of Spielbergs early movies…

Your less likely to break your legs skiing the American way with a board than the German one using skis.

And the Saturn 5 was a zb expensive (and fast) way of making a movie even with Spielberg’s budget.But just think of the land speed record that they could have got by putting it on it’s side and putting wheels on it instead.

[phil_the_book]

Carryfast:

bobthedog:
The “yanks” also invented snowboarding… Not all their ideas are that good, crazyfit.

Besides, do you really believe they went to the moon? I reckon that was one of Spielbergs early movies…

Your less likely to break your legs skiing the American way with a board than the German one using skis.

And the Saturn 5 was a zb expensive (and fast) way of making a movie even with Spielberg’s budget.But just think of the land speed record that they could have got by putting it on it’s side and putting wheels on it instead.

Was that 6X2,6X4 ,or 4X2 or did it have a tag?

[carryfast]

phil the book:

Carryfast:

bobthedog:
The “yanks” also invented snowboarding… Not all their ideas are that good, crazyfit.

Besides, do you really believe they went to the moon? I reckon that was one of Spielbergs early movies…

And the Saturn 5 was a zb expensive (and fast) way of making a movie even with Spielberg’s budget.But just think of the land speed record that they could have got by putting it on it’s side and putting wheels on it instead.

Was that 6X2,6X4 ,or 4X2 or did it have a tag?

The last time the yanks did something similar it only needed 3x0 like a rocket powered Reliant Robin or Scammel Scarab and that did 630 mph with just 58,000 horsepower.The Saturn 5 was a lot larger and heavier and it put out 160,000,000 horses so it would have been a bit quicker so I reckon that it would have been a 9 axle 18x0 running on supersingles with both a lifting tag and a midlift that lifted automatically at around 4,000-5,000 mph but that’s only a rough guess.Maybe kyrbo and btd could calculate some more accurate figures.

[rob_k]

about axle configs.

[philgor]

Rob K:

about axle configs.

hit nail on head

[newmercman]

philgor:

Rob K:

about axle configs.

hit nail on head

And yet here you both are reading the thread, did it not occur to you to continue hovering the mouse without clicking the button until you found something you do care about

[bowser]

newmercman:

philgor:

Rob K:

about axle configs.

hit nail on head

And yet here you both are reading the thread, did it not occur to you to continue hovering the mouse without clicking the button until you found something you do care about

what a strange radiator that is … and look at the height of those windows job and a half cleaning them buggers …

[bobthedog]

And why have they put the striplights right by the windows??

[rob_k]

newmercman:
And yet here you both are reading the thread, did it not occur to you to continue hovering the mouse without clicking the button until you found something you do care about

My humblest apologies Mr Lee . You guys just keep going round in circles and as mentioned elsewhere when people refuse to even acknowledge/consider your opinion and keep on trotting out the same BS then there is no point “debating” with them.

I shall now return to my hole.

[newmercman]

Rob K:

newmercman:
And yet here you both are reading the thread, did it not occur to you to continue hovering the mouse without clicking the button until you found something you do care about

My humblest apologies Mr Lee . You guys just keep going round in circles and as mentioned elsewhere when people refuse to even acknowledge/consider your opinion and keep on trotting out the same BS then there is no point “debating” with them.

I shall now return to my hole.

There are none so blind as those that won’t see, carryfast is the perfect example

I may find a hole for myself, I’m all axle’d out, I’m quite sure that every angle has been covered numerous times, by numerous posters, this thread is now beyond dead, I’m outa here…

[bobthedog]

Personally, I think we should all have tri drive and four axle trailers. Just imagine how much fun we could have then…

[kyrbo]

Sorry for resurrecting this thread, but I didn’t have anything better to do at the moment

Carryfast:
… 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. …

You almost got it right, but you left some important pieces out of equation.

What I agree with is that more drive axles reduces amount of force transferred by wheels to overcome the inertia.

What you didn’t take into account, or you didn’t mention, is you have to use cross and difflocks if you want to sum the forces affecting at each driving wheel. Of course, traction coefficient can be high enough that you don’t get any wheel spin at the first place, but it isn’t a situation we’re interested about. Lets again throw some numbers so the principle gets somewhat easier to understand. Lets stay you need 90 units of force to overcome inertia of your vehicle. Then lets use same legal setup I used in my previous post where I showed how 4x2 can transfer 47% more and 6x2 tag axle unit 100% more force to a solid surface than 6x4 unit before wheel spin occurs.

Lets say you can get 100 units of forward force per driving wheel on a 6x4 unit, which means 147 units of forward force per 4x2 unit driving wheel and 200 units for 6x2. If your throttle goes deep enough it’ll shoot power output of the engine over the limit allowed by traction coefficient between tyres and surface. This gives you wheel spin, which effectively cuts forward force by huge amount (no TC is assumed). For a 6x4 your margin between wheel spin and getting moving is 100-90=10 units of force. For 4x2 the marginal is 147-90=57 units of force and for 6x2 its 200-90=110 units of force. If you have clutch, lifting it up is likely to create a sudden rise in power transmitted to drivetrain which generates impulse type raise in the force which tyre should transfer. If amount of the force needed to overcome inertia and the amount of force tyre can transfer are close enough, this impulse is likely enough to invoke wheel spin.

When you engage diff or crosslock on 6x4 you have margin of 2100-90=110 units of force before you get wheel spin which will cut off your forward driving force. This is as much as you get from 6x2 out of the box. When you engage diff and crosslocks on 6x4 you have margin of 4100-90=310 units of force before you get wheel spin that stops you. Surprisingly, from 6x2 unit you get 2*200-90=310 units of force, which is same amount you get from your 6x4 unit. Differences which matter are that you have to engage some locks on a 6x4 before it matches traction give by 6x2. This requires you either to stop down or risk a breaking down your differentials on a long run when you lock them repeatedly while moving.

What I didn’t take into account is increased drag of the 6x4 (extra axle). I also didn’t take the increase in the surface pressure between tyre and surface into account with 4x2 and 6x2. This also has an (increasing) effect on the traction coefficient. Less surface supporting the same weight allows tyres to touch surface better than if you distribute the weight on a larger surface (think about hydroplaning or compare rally car tyres on a winter rallies to tyres used on an asphalt rallies).

Carryfast:
… ice is ice and snow is snow wether it’s 20 below or just 2 degrees below freezing. …

Actually it’s not. I’ll leave that to you as a homework to go out and check it by yourself how much more grip you have on ice and snow when it’s -20C compared to -2C.

[carryfast]

Kyrbo:
Sorry for resurrecting this thread, but I didn’t have anything better to do at the moment

Carryfast:
… 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. …

You almost got it right, but you left some important pieces out of equation.

What I agree with is that more drive axles reduces amount of force transferred by wheels to overcome the inertia.

If this discussion continues it’ll bring down more wrath from the thought police .More drive axles reduces the amount of force ‘required’ to be transferred by the wheels to the road to overcome the inertia of the total weight of the vehicle.Therefore less chance of any wheelspin taking place at either side of the drive axles so no need for diff locks or cross locks ‘unless’ ‘until’ traction is lost.The rest of the figures don’t seem to reflect the difference in traction between double drive and single drive in the real world.If the figures are right then someone’s zb’d up big time with the spec of these.

roadtransport.com/blogs/big- … lough.html

[philgor]

6x2 tag stuck in sand 24mtr rig

- YouTube

4x6/2 stuck in sand again

Garbage truck stuck in a sand pit.

4x2 artic stuck in grit/sand again

truck stuck in grit

6x4 yanktank artic stuck

big truck stuck in mud

6x4 tractor unit stuck on the grass/mud

Truck Stuck in Mud at the County Fair

so witch one is best, or which one is crazyfarce is going to use for his superduper roadtrain?

fixed the [ZBing] youtube links