4x4 Action Group

Having an interesting conversation on the subject....


What is the difference and why is there even a difference?

This is such a click bait post...

The first one (4x4) means the vehicle has 4 wheels and and can be driven (has traction) on all 4
The second (4WD) means 4 of the wheels can have drive (note the omission of how many wheels there are)
The third (AWD) means that all the wheels have drive (traction/power)

There is no difference..'
except the latter do not account for how many wheels the vehicle has

Tractive aids can be added to any of these.. Center diff lock, traction control axle diff locks,dual or multi ranges etc...

If you have an open center diff on any vehicle, it can be any of the above...
If you have a locked, or no center diff you can have any of the three.

Its all just semantics.. But you will get okies who will state they are not.

So.. Ill go get the popcorn, and read, and giggle

So, the term '4x4' actually goes back to steam power...

Steam engines were described by the total number of wheels and by how many were driven known as the Whyte notation.

effectively, a loco had a trailing set of wheels, big drive wheels in the middle, and a leading set of wheels.

so, a 4-6-2 loco had 4 leading wheels, 6 driven wheels (which have to be coupled (i.e. no differential movement between pairs) on a steam piston vehicle) plus 2 trailing wheels

this beast was a 2-8-8-4 - 2 leading wheels, a set of 8 coupled drive wheels, followed by another 8 drive wheels followed by 4 trailing wheels.

that was pretty much carried over into road parlance . the first 4WD petrol engined vehicle was actually built before 1900 - I forget the make.

the term All Wheel Drive was originally coined to describe any multi axle vehicle that had all wheels driven - which was important for the military as road use for moving troops and gear was one thing - combat zones require All wheel drive

the military then decided they needed something more descriptive so they started to the system as wee know it - number of wheels, number of driven wheels - e.g. 4x4, 4x2, 6x4, 6x6 8x4 8x8 etc.

so, generally, 4x4 and 4WD really meant ' all wheels driven for off road use' and when road cars started to use 4WD for traction and performance it kind of became AWD.

Obviously - with the rise of SUVs that line has become very blurred.

Also, there are many systems to drive all the wheels besides of a big old set of gears or chains - fluid drives, synchro type variable torque etc.

So, as always, some the society of automotive engineers came up with a standard called 'SAE International standard J1952' to prevent any confusion .

Under that standard All systems that drive all the wheels on a vehicle are referred to as AWD. easy!

Hedgehog wrote: ↑

Mon Aug 26, 2019 11:31 am

This is such a click bait post...

The first one (4x4) means the vehicle has 4 wheels and and can be driven (has traction) on all 4
The second (4WD) means 4 of the wheels can have drive (note the omission of how many wheels there are)
The third (AWD) means that all the wheels have drive (traction/power)

There is no difference..'
except the latter do not account for how many wheels the vehicle has

Tractive aids can be added to any of these.. Center diff lock, traction control axle diff locks,dual or multi ranges etc...

If you have an open center diff on any vehicle, it can be any of the above...
If you have a locked, or no center diff you can have any of the three.

Its all just semantics.. But you will get okies who will state they are not.

So.. Ill go get the popcorn, and read, and giggle

correct.

but it wasn't actually clickbait.

I was waiting for Manny to pontificate and you ruined it**









** Manny says we can't say f u c k ed it up on the forum

from Wiki:


SAE Recommended Practices[edit]
Per the SAE International standard J1952, AWD is the preferred term for all the systems described above. The standard subdivides AWD systems into three categories.[4]

Part-Time AWD systems require driver intervention to couple and decouple the secondary axle from the primarily driven axle and these systems do not have a center differential (or similar device). The definition notes that part-time systems may have a low range.

Full-Time AWD systems drive both front and rear axles at all times via a center (inter-axle) differential. The torque split of that differential may be fixed or variable depending on the type of center differential. This system can be used on any surface at any speed. The definition does not address inclusion or exclusion of a low range gear.

On-Demand AWD systems drive the secondary axle via an active or passive coupling device or "by an independently powered drive system". The standard notes that in some cases the secondary drive system may also provide the primary vehicle propulsion. An example is a hybrid AWD vehicle where the primary axle is driven by an internal combustion engine and secondary axle is driven by an electric motor. When the internal combustion engine is shut off the secondary, electrically driven axle is the only driven axle. On-demand systems function primarily with only one powered axle until torque is required by the second axle. At that point either a passive or active coupling sends torque to the secondary axle.

In addition to the above primary classifications the J1952 standard notes secondary classifications resulting in a total of eight system designations:

Part-Time Non Synchro System
Part-Time Synchro System
Full-Time Fixed Torque System
Full-Time Variable Torque Passive System
Full-Time Variable Torque Active System
On-Demand Synchro Variable Torque Passive System
On-Demand Synchro Variable Torque Active System
On-Demand Independently Powered Variable Torque Active System

this is interesting:

Ferdinand Porsche designed and built a four-wheel-driven electric vehicle for the k. u. k. Hofwagenfabrik Ludwig Lohner & Co. in Vienna in 1899, presented to the public during the 1900 World Exhibition in Paris. The vehicle was a series hybrid car, that used an electric hub motor at each wheel, powered by batteries, which were in turn charged by a gasoline-engine generator.[15][16] It was clumsily heavy and due to its unusual status the so-called Lohner-Porsche is not frequently given its credit as the first four-wheel-driven automobile.



actually, the whole article is interesting reading !


https://en.wikipedia.org/wiki/Four-wheel_drive

It’s true that semantics plays a part in the debate. Everyone had their own interpretation.

For example:

Apocalypse wrote:from Wiki:

Part-Time AWD systems require driver intervention to couple and decouple the secondary axle from the primarily driven axle and these systems do not have a center differential (or similar device). The definition notes that part-time systems may have a low range.

The Jeep XJ has a Part time system with that will lock 50/50 in high. Jeep uses this term because the system is used ‘part of the time’ & can’t be used all of the time (tar & off-road).

Nice thread Alex

And Hedgehog’s explanation is so that even a pleb like me can understand it

3WD??

Mad Manny wrote:What about Quattro, 4-Motion, 4 Matic and 4 wheel drive on demand?

Those are all AWD. 4WD on demand is ‘slip & grip’ so it’s also also associated with AWD.

XJ Junkie wrote: ↑

Mon Aug 26, 2019 3:38 pm

It’s true that semantics plays a part in the debate. Everyone had their own interpretation.

For example:

Apocalypse wrote:from Wiki:

Part-Time AWD systems require driver intervention to couple and decouple the secondary axle from the primarily driven axle and these systems do not have a center differential (or similar device). The definition notes that part-time systems may have a low range.

The Jeep XJ has a Part time system with that will lock 50/50 in high. Jeep uses this term because the system is used ‘part of the time’ & can’t be used all of the time (tar & off-road).

of course, you mean that when the centre diff is locked, you get equal output revolutions and torque transmission from 50/50 to 100/0 .....

FYI ...
... just an abstract ...

Quite correct,

Technically, everything from an angry Fiat Panda to a monster truck is an AWD .

However, I've always understood that '4x4' very specifically refers to a vehicle designed to go off road, and AWD refers to vehicles designed for tar and possibly a rough dirt road.

Hence.... Jimnys, Wranglers, Defenders (not the monstrosity that bears the name currently) , G wagens etc are 4x4s.

Metrosexual bakkies and station wagons on metrosexual bakkie platforms - hiluxes, rangers, frotuners and the like are AWDs.