Real four-wheel drive or imitation of locks — which is better off-road?

What are the more chances to get out of the impassable mud or cope with diagonal hanging? Simple «honest» SUVs versus clever electronic locks.

Which four-wheel drive is more efficient? Adepts of UAZ, «Niv» and other well-deserved off-road veterans go on the attack with a reinforced concrete argument: the simpler, the more reliable. Admirers of the modern school appeal to the versatility of the new four-wheel drive schemes: they increase the active safety of the car on flat roads (for example, in rain or snow) and, moreover, do not succumb to light off-road conditions.

Indeed, in domestic and old (which, in general, the same thing) SUVs do not find self-locking differentials and clever clutches that can redistribute traction depending on driving conditions. Instead of all these «excesses» there are honest iron differentials that do not know how to distribute anything themselves. But they do not know what overheating, wear of clutches or failure of control electronics is. These machines are as simple as an ax, for which they are still loved not only in Russia.

But the absolute majority of buyers do not need to drive the last couple of kilometers to the dacha on a muddy dirt road. And then the adherents of the old school attack again: yes, on your «off-road vehicles» instead of fair blocking, they are completely imitations! If you catch the diagonal, you won’t budge!

Diagonal hanging is a situation in which two of the four wheels located diagonally are in the air. If the inter-wheel differentials do not have the ability to lock, then even an all-wheel drive car will slip: the differential of each axle will spin the wheel that is easier for it. That is, hanging in the air.

Partly the criticizing side of the law: in a good half of modern crossovers in the mass and mid-price segment, four-wheel drive is practically helpless on the road. The entire off-road arsenal is often limited by the ability to block the interaxle coupling (it also plays the role of an interaxle differential). But all the same, you won’t ride in the mud for a long time — this function is not intended for long-term use. And the central locking will not save you from the «diagonal» anyway: as mentioned above, free cross-axle differentials will not move the car hanging on two wheels from its place. To get out of a geometric ambush, you must either block at least one wheel differential, or … imitate these locks! At least partially.

The imitation of cross-axle lock is one of the functions of the stability control system (ESP), which allows you to increase the torque on the wheel with better grip. Technically, it is implemented with standard brakes controlled by the ABS valve body. Wheel speed sensors detect which wheel is slipping and brake it with a caliper (or drum). Accordingly, the torque on the other wheel of the axle increases — due to which the car moves forward.

Imitation compares favorably with mechanical locking in that the differential is structurally the most common. Consequently, there is no complication, weighting and rise in the cost of the structure.

The downside is that by braking the skidding wheel, it is impossible to transfer 100% of the traction to the wheel standing on the ground. More precisely, it is possible, but not everyone succeeds — for a number of objective reasons, to which we will return below.

And, finally, we come close to the other side of the question posed in the title. Let me remind you that the criticism of the adherents of the classic all-wheel drive is based on an unshakable conviction: if there is no hard lock, then all these newfangled imitations are like a dead poultice. But for 2021, this is absolutely not true! Yes, it is still full of the most SUVs, some of which give way even in front of an ordinary city curb. But if we are to compare honestly, then the opponents of “real off-road vehicles” should be chosen from the best examples of “not real” ones.

Of course, crossover suspension articulation doesn’t match that of full-fledged SUVs. But in many emergency situations, no matter how much some would like otherwise, it is the torque and electronic assistants that decide. And in fact, «modern toys» are often raked out where old cars with a primitive design sit down.

So in which case simulations work fine and

Finally, do not discount the purely marketing point. Often, two crossovers of the same brand ride on intersections in completely different ways. The cheap one does not go at all (albeit with all-wheel drive), and the flagship model quite cheerfully overcomes the diagonals. And the point here is not always in the wild power of the latter — they often have the same ratio of mass and power, or even in favor of a cheaper model. It’s just that the status obliges, as they say. And this is precisely the question of the importance of settings at the design stage.

Firstly, if we talk about the weak abilities for off-road exploits of modern cars, then it should be clarified to whom exactly this applies. After all, if any «Chevrolet Captiva» at the slightest hanging out will helplessly twitch and knead the air with free wheels, then the Skoda Kodiak will pass this ambush playfully, crunching slightly with the brakes. And the basic UAZ «Hunter» or the classic «Niva», which do not have any interwheel locks or their imitations, are guaranteed to hang on the same diagonal (if they do not slip through). As for SUVs, that is, cars on a frame, often on bridges and with huge suspension travels, then the bias of the Old Believers’ attacks is all the more obvious. Don’t believe me? Then you can watch the video below. It more than clearly shows the operation of electronic off-road systems on heavy frame vehicles.

And the last thing. The criticizing side often “forgets” one more fundamental point: on many modern SUVs, despite all the electronics, there is additionally a rigid locking of the rear (or even the front one too!) Differential. The very one, iron and reliable. And when, in some 200 Land Cruiser, Gelendvagen or Range Rover, you turn on all possible locks and activate the off-road mode of electronics, then who, as a result, will remain sitting in the mud — these «dandies» or «honest iron UAZ» — a very big question.

Photos are taken from open sources.

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