4WD and 2x4 / 4x4 - What is the principle of operation and the difference in con

Hello,
I am writing transitional work on the analysis of suspension structures and I'm stuck. I do not really understand the difference between 4WD and 2x4 / 4x4.
I have read and understood that 4WD has a constant torque distribution on both axes in a 50/50 ratio. In addition, it has 3 differentials including one central, with the possibility of blocking or even detaching the front axle. But does having a central differential no longer contradict the thesis that the torque distribution is 50/50? Because I understand that 2x4 / 4x4 is a drive built with 2 differentials, without a central one, and only with an attached drive for the front, rear axle (eg a multi-plate clutch)?
greetings

There is no such division.
2x4 - the car has four wheels, including two driven - most cars.
4x4 car has four wheels, including six driven and it is the same as 4WD: 4 Wheel driving - or four-wheel drive.
In addition, there are still 6x6 cars (eg STAR 266), 4x6 vehicles (ie a truck with two rear axle drive), etc.

Thank you for your response
The main problem is the torque distribution. Is it true that 4WD has a 50/50 split?

No, this is not true.
Just 4x4 is 4WD.
The 50/50 split is when you do not have an inter-axial differential - one axis in the mud, the other on the concrete, both are spinning the same.

Each manufacturer calls it in his own way. You must refer to specific models.

That is the possibility of blocking. Can you tell me the difference between 4WD and AWD? I know that AWD dynamically changes the distribution of torque. However, if we use three differentials in 4WD, then it will not be a dynamic change?

AWD is in the subaru, and as such a subaru has an automaton, it has a dynamic distribution. But how such a subaru with AWD has a manual gearbox, it already has 50/50, and AWD is still there. So you probably have bad information. AWD is the same as 4wd, only subaru so-called se.

Whenever there is a differential or a viscous coupling, there is a dynamic moment change! By car 50/50 with the drive turned on you can not drive on hard roads. That is, da, but it is unpleasant and will lead to earlier wear or failure of the drive train. AND IS CATEGORICALLY PROHIBITED in the user manual.
I have UAZ, so I know what I'm saying.

When you have a differential, in the above case the torque distribution would be such that the axle less heavily loaded (eg in the air) will be transferred most of the moment and the axle loaded very little. It is only when the braking torque is applied to the unloaded axle - whether through the differential mechanism with increased internal friction or by vehicle brakes (ESP) - the drive torque is transmitted to the second axle.

Only by reading in the forums, is that there are differences between AWD and 4WD. But there are also forums where it does not separate, as you say.
The differences show that AWD has a constant torque distribution, in addition it is dynamically regulated. However, 4WD has a 50/50 torque distribution (which makes no sense if there is a working central differential) with the possibility of disconnecting the front axle. I'm beginning to understand that the promoter made a trick to me, giving me the two drives to compare

Give an exact subject commissioned by the promoter.

The topic is: Analysis of suspension design for all-wheel drive vehicles.
In one part I have to compare AWD and 4WD, while in another I have prepared to describe such a division:

Division of drive systems due to torque distribution (characteristics):
o manually connected (2x4 / 4x4) - it enables manual connection of the front drive, (Isuzu D-Max - classic terrain-utility solution, reliable and appreciated by off-roaders);
o constant, symmetrical (4WD) - three differential mechanisms;
o constant, active (DCCD, xDrive, ACD, ATS) - mechanically or electronically controlled differential mechanisms;
o permanent, with active blocking (Quadra-Trac Active 4WD, Quadra-Drive Active 4WD, Terrain Response) - a system enabling a more precise distribution of torque between axles and even individual wheels;
o periodically connected (TOD, Quadra-Trac, Quadra-Drive, VCU, Haldex, Select 4WDrive) - all-wheel drive automatically switched on depending on many factors: road conditions, drive settings and engine data;

You need to be specific about the model and brand of specific cars. Because these names do not say anything about the way the drive is transmitted. I drive Forester myself and you have All time AWD or SymetricalAWD. these names and numbers are the whole mass. And in Audi it's called Quatro and it's also AWD ...

I even met with the nomenclature that Quattro is 4WD. I will look and write what I decided
Thanks, gentlemen

You can take the promoter and describe a Star 266 car (with six-wheel drive), LPT (off-road vehicle on the basis of a toddler), SKOT vehicle (eight driven wheels) and finally vehicles bolted by braking all wheels on one side.

It was about generality, but when I am at the wall, I will do it

Added after 1 [hours]:

I judged in this way, agreeing with each of the parties:
o 4WD - there are two variants: fixed or attached (2x4 / 4x4). This is changed using the reducer (2H / 4H / 4L) mentioned below. In this drive, we manually set a suitable ratio "High" or "Low" and the central differential (or lack thereof) can be blocked, resulting in a 50/50 split in the power transferred to the drive axles. The driver has complete control over the changes in the drive. For this reason, 4WD is chosen by offroaders. Often it has the ability to turn the drive forward, which allows better traction control when turning on an asphalt road when there is no central differential. Switching can be done by moving the lever in the cabin. Unfortunately, in older vehicles, turn the front axle on or off outside the vehicle. Its further disadvantage is that the whole structure becomes much heavier than in the case of AWD. It is also disadvantageous to have a central differential on on-road roads, as we do not use the 50/50 facility.

o AWD - it can be compared to a permanent 4WD drive. Used in newer road and sports cars, as the separate torque improves traction control. It is a constant four-wheel drive, with the difference that it has dynamic (mechanical or electronic) power control. Typically, about 90% of torque is transferred to the front axle. Only in the event of loss of grip, power is redirected to the rear axle and can reach up to 90% of the power, eg by means of a viscous coupling. From 4WD it differs in that the driver can not disconnect the drive to one of the axes, and does not affect the torque distribution. Its disadvantage is that it can not cope in the field like 4WD just by separating the moment and increasing fuel consumption.

greetings

No unnecessary delving:
AWD - All Wheels Driving - if you have 4 wheels, four are driven, if 19 are 19 driven
4WD - 4 Wheels Driving - if you have four wheels you have all the power on all, if 19 are 15 without a drive
SAWD - Symetrical All Wheels Driving (a subaru patent applied in manual cases even 4-5 years ago) relies on a constant distribution of 50/50 power for both axles, regardless of anything (mechanically implemented by a viscous coupling - mechanics completely without electronics).
A colleague who said that it is impossible to ride - it can be done very well, the blockade consists of an additional constant speed distribution and so you can not really drive on the highway in the long run (see my subaru from SAWD). One of the disadvantages of the viscous coupling is the rigid clamping of the axis rotational speed after heating the oil in the clutch - then the car starts to shoot at tight corners (different speed of the axes and one must give up).
Torsen / multi-plate clutch - an electronic controlled clutch between the axes that joins the second axis (not always the back) at the moment when the computer orders and to the extent in which the computer orders. Torsen has several generations that differ in some details but this is a subject for the poem.
Other useful shortcuts:
FWD - Front Wheel Driving - driven front axle
RWD - Reverse Wheel Driving - driven rear axle