Well . . I know what I mean't and you can all argue as much as you like, but if a 4x4 was PERMANENT four wheel drive, then ALL FOUR wheels would turn with EQUAL force irrespective of the grip avaiable to each wheel (in a 4wd with all 3 diffs LOCKED, then yep that's exactly what you have got !!

If as stated above that the drive going into an axle via the diff is 100% and what comes out is also 100% (no debates about friction losses PLEASE) then . . . In a straight line, on good grip, I agree 50% will be applied to each wheel. Now here's MY argument, on mud/ice or off the ground completely, the wheel with NO grip will spin freely taking 100% of the available drive, so 0% to the one with grip, hence my view that it's ONE wheel drive (or no drive ?)

A motorbike is still one wheel drive (obviously) the difference is whether there is grip or not, but the ONE wheel will always rotate, so it can't ever be a no wheel drive, but could be a no wheel 'driven'

I think reading above, there is a preception that '4 wheel DRIVE' is the same as 4 wheel DRIVEN - well it ain't !!!!!

So . . I think we all could agree to disagree . . (being the polite chap that I am) and we are ALL entitled to our opinions . . .

Over to you chaps to shoot me down in flames I guess ??
 
Yep . . so the badge on the back would say . . .

THE BEST 1,7584X0.2416 X 1,7584X0.2416 X FAR

:D :D :D :D :D

(Bet you all will argue what it should ADD UP TO now :cool: :cool: )
 
Good Grief ..... some of the kids around here have a Hell Fire heap of understanding to acquire.

Oh well Slob and all the rest of us Mouldie Oldies, we'll just have to keep telling them ..... explaining .... educating ..... enlightening .... and all FREE!

So far ...

CharlesY
 
CharlesY said:
Good Grief ..... some of the kids around here have a Hell Fire heap of understanding to acquire.

Oh well Slob and all the rest of us Mouldie Oldies, we'll just have to keep telling them ..... explaining .... educating ..... enlightening .... and all FREE!

So far ...

CharlesY
Click to expand...

Why thanks for the compliment, being refered to as 'kid' was quite charming . . . (as I'm 50 this year :eek:)

This is what Wikipedia has to say on the subject, funny that it says that when ONE wheel is spinning, ALL the drive will be lost through that wheel :D

"Hypothetically, suppose that the left front wheel slips on an icy patch of road with a design that drives all four wheels: the slipping wheel will receive all of the power, causing it to spin twice as fast as desired, while the wheel on the other side stops moving. The average speed remains unchanged, and neither wheel gets any torque. A similar problem occurs between the front and rear axles via the center differential. The front left wheel receives all of the power, again doubling its speed while the rear wheels stop moving; again, the average speed is maintained. The available torque goes to zero, and the left front wheel actually turns four times as fast as it should be turning, preventing the other three wheels from turning. This problem can happen in both 2WD and 4WD vehicles, whenever a driven wheel is placed on a patch of slick ice or raised off the ground"

I think we may have exhuasted this thread now, I bet when the guy started it he didn't bargain on all this banter :D :D :D :D :D
 
disco_steve said:
Why thanks for the compliment, being refered to as 'kid' was quite charming . . . (as I'm 50 this year :eek:)

This is what Wikipedia has to say on the subject, funny that it says that when ONE wheel is spinning, ALL the drive will be lost through that wheel :D

Where does it say that?

"Hypothetically, suppose that the left front wheel slips on an icy patch of road with a design that drives all four wheels: the slipping wheel will receive all of the power,

WRONG! It will spin, but equal TORQUE will apply to the other wheel on the same axle. The force APPLIED TO THE GROUND by each wheel will always be equal. Also, equal torque will apply to the two prop shafts (front and rear).

causing it to spin twice as fast as desired, while the wheel on the other side stops moving. The average speed remains unchanged, and neither wheel gets any torque.

CORRECT! But this contradicts their first assertation which is incorrect.

A similar problem occurs between the front and rear axles via the center differential. The front left wheel receives all of the power,

WRONG!! It lost grip, it speeds up, it does NOT receive all of the power!

again doubling its speed while the rear wheels stop moving; again, the average speed is maintained. The available torque goes to zero,

CORRECT!


and the left front wheel actually turns four times as fast as it should be turning, preventing the other three wheels from turning.

CORRECT ! So we now have NO drive to any of the 4 wheels!

This problem can happen in both 2WD and 4WD vehicles, whenever a driven wheel is placed on a patch of slick ice or raised off the ground"

I think we may have exhausted this thread now, I bet when the guy started it he didn't bargain on all this banter :D :D :D :D :D
Click to expand...

Not exhausted until everyone understands the principles. It is called learning. It isn't "banter". A lot of LZers are happy to pick up information from these threads.

CharlesY
 
"The force APPLIED TO THE GROUND by each wheel will always be equal"

COMPLETLY INCORRECT, It ONLY applies when there is EQUAL traction available to BOTH wheels

This is WHY I say that:-

Torque applied to a wheel DOES NOT equal FORCE APPLIED TO THE GROUND, (Force = 'TRACTION')

There are two factors that determine how much torque can be applied to the wheels: gearing and traction. In dry conditions, when there is plenty of traction, the amount of torque applied to the wheels is limited by the engine and gearing; in a low traction situation, such as when driving on ice, the amount of torque is limited to the greatest amount that will not cause a wheel to slip under those conditions. So, even though a car may be able to produce more torque, there needs to be enough traction to transmit that torque to the ground. If you give the car more gas after the wheels start to slip, the wheels will just spin faster.

It doesn't take much torque to make the tyre slip on ice (or mud). And when the wheel with good traction is only getting the very small amount of torque that can be applied to the wheel with less traction, your car isn't going to move very much.

If you have a four-wheel drive vehicle, with an open differential on both the front and the back, you can easily get stuck. the open differential always applies the same torque to both wheels. If one of the front wheels and one of the back wheels comes off the ground, they will just spin helplessly in the air, and you won't be able to move at all.

have a look at this:-

Howstuffworks "Open Differentials"

There are a couple of nice animations, in the 'turning' one, you can see that one planet cog turns faster than the other, so if the slower one stopped completely, all the drive (torque) would basically direct through 90 deg to the spinning wheel - this is what happens when one wheel encounters no traction
 
robint said:
i have had conflicting answers !!!
i have a 300 tdi disco on a r plate (97) ...
people are telling me its perminant 4 wheel drive ???
some say its 2 wheel drive .....
so many people had said so many different things !!!!
whats the bloody answer (please)
thankyou
Click to expand...

HI ITS ALLWAYS IN 4 WHEEL DRIVE M8
THAT Y THERE THE KING OF 4X4 LANDROVER RULE
 
keep me informed Pikey - i am more interested in yo violin lessons than the technicalities of differential workings;)
 
RIGHT ............
so after all this ????
whats the answer !!!!!!!!!!!!
buggar more confused now than when i started !!!!!!!!!!!
"rolleyes"
 
its 4wd!
OR TO BE MORE PRECISE

--------------------------------------------------------------------------------

It's permanent 4wd with a centre difflock.
 
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