Four-wheel drive. Advantages and disadvantages

Recently, crossovers are gaining more and more popularity, and are in constant demand among consumers.

What is the whole secret? And how to choose the right crossover with the necessary equipment? Let's try to answer these questions.

Reasoning logic when choosing the right equipment

The crossover in its build can be attributed to a light SUV. Everything is combined in one car consumer qualities car: from high ground clearance to all-wheel drive system. Using a large ground clearance, the crossover can easily drive on the highest curbs, and using the all-wheel drive system, you can easily leave the most difficult snowdrifts.

Each crossover has its own characteristics, some consumers choose high ground clearance, some drive, and someone spacious salon. How to do right choice? Crossovers can be with a plug-in front or rear axle, or can go with permanent all-wheel drive. In order to navigate in such a system, it is necessary to consider what crossovers with permanent all-wheel drive are.

Chinese supplier GreatWall offered crossovers with all-wheel drive, among them are Chevrolet Niva in the price category 459000-55700 rubles and crossover Lada 4 × 4 with a price of 354,000 rubles. These cars, regardless of the year of manufacture, are always very popular with consumers, with permanently connected all-wheel drive and the same distribution of wheel torque on all axles of the crossover.

All 4x4 crossovers require good driving skills and an understanding of how the vehicle works. All cars practically come with independent rear suspension MCPherson type. This feature is necessary in order to fully experience the properties of the car.

Usually, when a car enthusiast is going to buy a crossover, he pays attention to all-wheel drive crossovers with high ground clearance. In such cars, there is no differential lock and a decrease in transmission gears. Such a crossover is great for a comfortable ride in the winter, and for roads in the warm season, it will delight with its smooth ride. high ground clearance does not affect price category car, because basically everyone pays attention to the compactness of the model and its dynamism. Basically, these crossovers are not found off-road, but on a regular highway, which also excludes the choice of a crossover with high ground clearance.

The list of the most popular crossovers with high ground clearance includes: Opel Moka (with a clearance of 19 cm), Chevrolet Tracker (with a clearance of 15.9 cm) - we learned about it in some detail from. Nissan Juke Nismo (18cm ground clearance), Toyota RAV4 (19.7cm ground clearance), Infiniti JX (18.7cm ground clearance), Subaru Forester(with a clearance of 21.5 cm), Volvo XC60 (with a clearance of 23 cm) and range rover E-Voque (with a clearance of 21.5 cm). Crossover Range Rover E-Voque is considered the best crossover in its class.

Crossovers can hardly be called real SUVs, since ground clearance SUVs are 30 cm, but they have fewer opportunities than crossovers. Depending on the configuration of the car, their ground clearance will change. Basically, if the model belongs to microcrossovers ( Chevrolet model Tracker), then the clearance will be smaller here. Microcrossovers due to their compact configuration are often referred to as sedan type cars. The main reason that distinguishes crossovers from SUVs is the comfortable ride of the first in urban areas and light off-road.

Crossovers with plug-in all-wheel drive

If the drive is connected through a clutch, in this case the units are called crossovers with all-wheel drive. That is, the clutch connects the second axle, depending on how the wheels scroll from the non-connected axle. This type of drive can rightly be attributed to the intellectual type. Usually the second axle is automatically connected depending on the type of road: road / off-road. If, however, use four-wheel drive on an uncharacteristic road, you can damage the mechanisms in the car.

Therefore, the question "Does the crossover need all-wheel drive?" can be answered this way: “Needed if the transport deals with constant off-road, and constant difficult situations on the road, bad weather conditions, snowdrifts and mud. If the crossover is spent most of the time on the road, it is better to use a single-wheel drive car, most often with a rear axle. The ideal option will be buying a crossover car with plug-in all-wheel drive.”

Among rear wheel drive vehicles with plug-in front-wheel drive, such popular crossovers can be distinguished: Suzuki Jimny in the amount of 746,000 rubles, UAZ Patriot and UAZ Hunter in the amount of 529,000 rubles and 454,000 rubles. Also crossovers HoverM2, HoverH3, HoverH5, HoverH6 from 549,000 rubles to 749,000 rubles.

A striking example of front-wheel drive crossovers with rear-wheel drive connected using a clutch is: Renault Duster in the amount of 541,000 rubles, Chery Tiggo in the amount of 619,000 rubles and Suzuki SX4 Classic in the amount of 729,000 rubles.

Excluding all-wheel drive for SUVs, there are single-wheel drive vehicles, mostly front-wheel drive, called crossovers for use in urban areas. These crossovers have a much lower price than all-wheel drive relatives. Front-wheel drive crossovers will perform better off-road than rear-wheel drive ones. The drive axle of such cars is always under load, as the engine constantly weighs on top, making it better grip on the road surface. By rotating the wheels with the steering wheel, you can easily maneuver in any situation on the road.

Pricing for crossovers

Usually front-wheel drive crossovers are obtained from a simplified version of the all-wheel drive unit. To get acquainted with the prices of such a control system, it is proposed to view the front-wheel drive crossovers review:

• Suzuki SX4 New cost 779,000 - 1,019,000 rubles;
• Nissan Qashqai cost 789,000 - 1,096,000 rubles;
• Nissan Qashqai +2 cost 844000-1049500 rubles;
• Citoren C4 Aircross cost 849,000 - 1,124,000 rubles;
• Kia Sportage cost 889,900 - 1,049,900 rubles;
• Hyundai ix35 cost 899000 - 1,144,900 rubles;
• Mitsubishi Outlander cost 969,000 - 1,249,990 rubles;
• Peugeot 4007 cost 989,000 - 1,074,000 rubles.

Basically, the price of cars depends on whether the equipment will be with all-wheel drive or not, what ground clearance is installed in the crossover, what type of McPherson front and rear suspension (mostly semi-independent), what kind of rear and front axle brakes. As a rule, in front-wheel drive crossovers, the ground clearance is at least 175 mm, wheelbase 2.5-2.6 m. They can easily pass the curb and pits on the primer, which makes them an indispensable choice for Russians.

Front-wheel drive crossovers have the guts of a small or medium power gasoline engine. Crossovers come with one engine, only some models use two options at once. Some models of front-wheel drive crossovers such as Kia Soul go with diesel engine, only price policy goes beyond budget cars.

Due to the fact that the car is equipped with a single drive, it consumes 2-3 times less fuel than an all-wheel drive crossover. Most crossovers come with a manual transmission, automatic transmission gear shifting is not included in the category of 750,000 rubles. Mostly in Europe, on the contrary, they choose mechanical box gears, as it consumes less fuel.

Thus, the more complete sets are installed in the crossover, the more expensive it is. Upon request, by purchasing front-wheel drive crossover, you can constantly supply it with new parts and install new packages, thus the price will not be so expensive when buying. Do you need all-wheel drive? The question is serious, it all depends on the real need or the great desire of the driver. Before buying a car, evaluate the pros and cons of buying the right drive.

In this detailed test drive, the new Great Wall Hover H6 absolutely justifiably called "thoroughbred" for its all-wheel drive:

Let's talk about all-wheel drive, you will learn about the advantages and disadvantages of all-wheel drive, as well as what all-wheel drive is like.

Once upon a time, a similar topic was already raised, in which I reasoned. Today I decided to supplement the series of articles on car drives with another, quite logical topic about all-wheel drive cars.

For some, this topic will seem strange, since most motorists consider all-wheel drive to be flawless and reliable, but practice and numerous reviews cast doubt on this statement.

To begin with, I want to make some clarity about what all-wheel drive is and how it happens. Four-wheel drive is a type of drive in which the input from the transmission is transmitted to all four wheels. All-wheel drive cars can have permanent all-wheel drive (AWD) or plug-in (4WD). The differences between the first and second types are quite understandable, in my opinion, in the first case, you constantly have four driving wheels without the ability to turn off the front or rear axle. In the second case, there is such an opportunity, and the driver, at his discretion, decides when and under what circumstances to connect the front or rear axle, and turn his car into an all-wheel drive and vice versa.

With permanent all-wheel drive, everything is more or less clear, but why the ability to connect a drive? And you need it in the following cases:

1. When one drive does not cope with its task, for example, when a car is bogged down in the mud;
2. In the case when the track is slippery and to increase stability, the driver can use all-wheel drive;
3. All-wheel drive allows you to accelerate better from a standstill, and improves the dynamics of the car.

Why is it necessary to disable all-wheel drive?

All-wheel drive is turned off most often for the following reasons:

1. Driving on a flat, clean track, where there is no need to use all-wheel drive and spend torque on the rotation of another axle;
2. Reducing the noise level, which increases when connecting additional. axes;
3. Riding in certain conditions where only the rear or front-wheel drive(for example, sports).

The distribution of torque is due to the differential. In modern all-wheel drive cars, as many as three differentials can be used. Each of them allows you to distribute torque to one or another axle, depending on the needs of the driver or according to the settings laid down during the production of this car. There are central, front and, of course, rear differentials. The central one experiences the load more than others, since its task is to obtain torque and distribute it among the rest of the differentials.

It should also be noted that all-wheel drive does not always evenly distribute torque along the axes. Quite often, owners do not even realize that, for example, the front axle in their car receives only 40% of the torque, and the remaining 60% goes to the rear axle. Also in the new all-wheel drive systems, the electronics are able to "intelligently" distribute the force along the axles, on which there is a better grip with the road surface.

Advantages of all-wheel drive

Now I propose to briefly list the main advantages of all-wheel drive cars.

1. Well, first of all, this is an increased cross-country ability, when it comes to SUVs and crossovers.
2. Sustainability. Today, you will not surprise anyone with an all-wheel drive sedan, hatchback or coupe. Four driving wheels improve the dynamics and stability of the car on the road. A sharp start without slipping is common for an all-wheel drive car, while on a front- or rear-wheel drive car, a sharp start almost always ends in slipping.
3. On slippery roads, all-wheel drive vehicles are more stable and the wheels are less prone to spin because all four wheels are working.

Cons of all-wheel drive

As I said, despite the many advantages, all-wheel drive also has disadvantages.

1. The main disadvantage is, perhaps, fuel consumption. For all-wheel drive cars, it is, as a rule, always higher than for similar cars with a single drive, take at least, which is found in both front- and all-wheel drive versions.
2. The second drawback is expensive repairs and maintenance. Due to the complex structure and heavy loads, the drive mechanisms often fail, complicating the situation is the fact that repairs are expensive. Plus, it’s not possible to repair the “bridge” or replace gears at every service station; you will have to look for a service that specializes in this kind of work.
3. The weight. All-wheel drive cars have a more complex device and more nodes that make it heavier in order of weight.
4. No matter how strange it may sound, but sometimes the presence of all-wheel drive on a slippery road turns out to be a big drawback. Of course, the car is more resistant to skidding and slippage, but if the car is already incurring, then leveling the all-wheel drive car is much more difficult, especially for beginners. As you know, when driving on a rear-wheel drive car on a slippery road, if the car starts to rock, most often it’s enough just to let go of the gas and make a few right movements with the steering wheel. On front-wheel drive, on the contrary, it is recommended to add gas, as a result of which the car comes out of a skid. But on all-wheel drive cars, as I said, if the car goes into a skid, then only the pros can cope with this unpleasant phenomenon, and even then not always. Beginners, in most cases, simply do not know how to behave, turn off the gas, how to rear wheel drive or add like on the front?

Also, it was not uncommon to hear about the inadequate operation of all-wheel drive systems, when the car for no reason fell into a skid and generally refused to respond to the steering wheel and pedals. While monoprivodny cars overcame this section without any problems.

Summing up the above, I want to note that any type of drive has its pros and cons. All-wheel drive is no exception, in some situations these are solid pluses, and in others - some minuses. If you like to drive and know a lot about cars, then an all-wheel drive sedan or station wagon will come in handy. The same can be said for off-road enthusiasts, if you often travel on bad roads or rough terrain, then all-wheel drive is what you need. If you mainly drive around the city or town, save fuel, do not plan to race and do not like off-road, then I can safely say that four-wheel drive is not for you!

In general, everything largely depends on a particular situation, as well as the skills of the driver and his ability to control the car. I have everything, I hope I was able to reveal the topic and weigh all the pros and cons. Write in the comments what you think about this and what the pros and cons of all-wheel drive are known to you, and of course, share your experience in owning and driving all-wheel drive cars. I would also be grateful for the repost of this article in social media, for this there are special buttons at the bottom of the article.

All the best and good luck on the road! Till!

The main and unchanged "actor" of all all-wheel drive systems is the transfer case: a special unit that receives torque from the gearbox and distributes it to the front and rear axles. But there are several distribution methods, as well as layout schemes.

All-wheel drive systems are usually divided into three types:

Permanent four-wheel drive (Full-time)

Pros:

• reliable "indestructible" design;
• the ability to drive with all-wheel drive both off-road and on asphalt.

4Matic permanent all-wheel drive system (Mercedes-Benz)

Minuses:

• complexity compared to a hard-wired drive;
• large mass;
• complexity of controllability settings;
• increased consumption fuel.

The first thing that comes to mind when there is a task to transfer torque to two axles is to rigidly connect them to the razdatka with iron pipes. But here's the problem: when cornering, the wheels of the car pass different paths.

If the axles are rigidly connected, then some wheels will drive, and some will slip. In the mud, when the surface is soft, it's not scary. During the Second World War, for example, the legendary "Willis" quietly drove with rigidly connected axles, because they were operated exclusively on off-road. But if the coating is hard, then these slips will generate torsional vibrations and slowly but surely destroy the transmission.

Therefore, in the transfer case of cars with permanent all-wheel drive, there is an interaxle differential - a mechanism that distributes power between the axles and allows them to rotate at different speeds. And if one wheel slows down, then the speed of the other increases, but the torque on it also drops by the same amount.

All this is great while we are driving on asphalt, but what if we are stuck in a puddle with the rear axle? On the front wheels, which will stand on a hard surface, there will be moment but there will be no revolutions, but the rear wheels will rotate very quickly, but the moment on them will be small. The power will also be small. rear wheel and the differential will deliver exactly the same power to the front end. In this case, you can skid for at least an eternity - you still won’t move.

For such cases, the differential is equipped with a lock - when it is turned on, the speed on all wheels is the same, and the moment depends only on the adhesion of the wheels to the road.

Due to the presence of additional nodes (differential and blocking), the whole system turns out to be quite heavy and complex. In addition, the constant transmission of torque to all wheels increases energy losses, which means it worsens dynamics and increases fuel consumption.

Permanent four-wheel drive in the automotive industry is still used, although in recent times this system has been gradually replacing four-wheel drive on demand, which will be discussed later.

Hardwired (Part-time)

Pros:

• reliable mechanics;
• maximum simplicity with high throughput.

Minuses:

• You can't drive on asphalt with all-wheel drive.

The differential and locks can also be abandoned, provided that one of the axles is temporarily disabled. According to this logic, the hard-wired all-wheel drive system works.

The axles are connected to each other without a differential, and the moment is distributed in a strict ratio. As a result, high throughput and minimum costs.

Part-time is practically extinct today and is used only on purely off-road vehicles. It is inconvenient for a modern driver to use this system. It is possible to connect the axis only in a stationary state, so as not to damage the mechanisms. Well, if after riding in the forest you go onto the highway and forget to turn off the four-wheel drive, then there is a risk of ruining the entire transmission.

All wheel drive with clutch

Pros:

• low cost and simplicity of the device;
• small mass;
• the ability to fine-tune the system.

Minuses:

• poor reliability and resistance to overloads;
• characteristics instability.

A hard differential lock is not bad off-road, but how do you get the all-wheel drive system to dose the moment in dynamics? The degree of slippage is always different ... The solution was found in the mid-50s.

Active Torque Split AWD system for Mazda CX-7 with multi-plate clutch instead center differential

The usual mechanical differential was supplemented with a viscous coupling (viscous coupling). A viscous coupling is a part in which rows of blades connected to the input and output shafts rotate in a special fluid. The input and output shafts rotate freely relative to each other, but the secret of the coupling is in the filler, which increases its viscosity with increasing temperature.

During normal movement, light turns or wheel slippage, the clutch does not prevent the mutual movement of the blades, but as soon as the difference in the speed of rotation of the front and rear wheels rises, the liquid begins to intensively mix and heat up. At the same time, it becomes viscous and blocks the movement of the blades relative to each other. The greater the difference, the higher the viscosity and the degree of blocking.

Today, clutches are used both in schemes with permanent all-wheel drive in conjunction with mechanical differentials, and independently. They are connected by the drive shaft to the transfer case, and by the driven shaft - to the additional axle. If necessary, when one of the axles slipped, part of the moment goes to it through the clutch. What's next?

The further evolution of all-wheel drive systems, most likely, will be associated with electric motors. The first electric car with an engine on each wheel was shown at the World Exhibition in Paris in 1900 by Ferdinand Porsche. Then it was, as they would say now, "unviable concept car." The motors were too heavy and the construction expensive. Now such a scheme has clearly more prospects.

There is also potential for a hybrid scheme, where one axle is driven by an engine. internal combustion, and the second - an electric motor. However, if we talk about real SUVs, then no electrical innovations and friction clutches will yet replace cheap, simple and hardy mechanics.

The number of all kinds of SUVs and crossovers on our roads is growing at a tremendous pace. One of the main advantages of such cars is the all-wheel drive system, the principle of operation of which can differ significantly for different models.

All types of all-wheel drive can be divided into three main ones: temporarily connected (Part Time), permanent (Full Time) and automatically connected (On Demand Full Time).

Temporarily connected all-wheel drive

Temporary all-wheel drive, or as it is often called Part Time, does not allow you to drive in all-wheel drive for a long time. In this type of all-wheel drive, there is no center differential that would compensate for the difference in the speed of rotation of the front and rear axles. Without it, when driving on a dry road, transmission parts begin to wear out quickly.

All-wheel drive Part Time can only be forcibly connected to overcome a difficult section of the road at low speed.

Usually a lever is used to connect transfer box transmission. Although in some versions to connect front axle you need to get out of the car and turn the special handles (hubs) on the front wheel hubs.

Only “full-fledged” SUVs that are used for their intended purpose are equipped with temporarily connected all-wheel drive. Bright representatives of such "rogues" can be called and who are in no hurry to give control of all-wheel drive to electronic "brains".

In addition, almost all Chinese copies of famous SUVs of the 90s are equipped with “temporary” all-wheel drive.

Real SUVs with "fair" Part Tim modee are slowly fading into history as more modern all-wheel drive systems replace them.

Permanent four-wheel drive

Permanent four-wheel drive, or FullTime, most manufacturers do not allow you to force disconnect / connect one of the bridges.

Due to the presence of a center differential, such a transmission constantly (in any conditions) operates in all-wheel drive mode. In addition, in modern models, the center "diff" has its own electronic "brains".

With such a differential, torque can be transmitted to the axles in different proportions, that is, not only 50/50. When slip occurs, the “smart” differential can instantly “transfer” torque not only to the axle with better grip, but even to a separate wheel that has something to catch on.

This type of all-wheel drive is the most "advanced" among other 4x4 systems.

The abundance of "smart" electronics on the most modern systems allows the car to adapt even to a specific pavement(asphalt, gravel, sand, etc.), the driver only needs to press the desired button.

The most famous representatives of permanent all-wheel drive are the company, with the proprietary Quattro system, and Subaru with the AWD (All Wheel Drive) system.

Interestingly, this type of transmission is equipped with completely “non-off-road” sedans, coupes and hatchbacks. This highlights the versatility of this all-wheel drive system.

Automatic all-wheel drive

Automatic all-wheel drive (On Demand Full Time) allows the car to remain front-wheel drive and only in the event of slipping of the drive wheels connects the rear axle. Automatic connection all-wheel drive in modern systems occurs almost instantly at the first sign of slipping.

Depending on the capabilities of a particular system, the torque between the axles can be redistributed in any proportion (from 10/90 to 90/10).

At the same time, the electronic stability program (ESP) allows you to maintain control over the car, which can suddenly turn from front-wheel drive to rear-wheel drive, and vice versa.

To overcome a particularly difficult section of the road, this type of drive (in most versions) makes it possible to forcibly redistribute the “floating” torque between the axles in a 50/50 ratio. Usually there is a button for this that says 50/50, Lock, etc. But when a certain speed is reached (40-50 km / h), the blocking will turn off, and the system will return to the “floating mode”.

In addition, a car with automatically connected all-wheel drive can be turned into a purely front-wheel drive, without any connections. Again, using the "magic" button (2WD, etc.). Disabling all-wheel drive helps save fuel, and the need for four-wheel drive in the city does not often arise.

Automatic all-wheel drive is the "youngest" of the 4x4 systems.

They are equipped with the vast majority of crossovers in our market. You can even say that such a drive is an essential attribute of a real crossover. A new type of car required a new type of all-wheel drive, everything is logical.

Which drive is full her?

It is rather difficult to determine which all-wheel drive is the most optimal, since each of them has its own advantages and disadvantages.

On serious off-road, off-road vehicles with temporarily connected all-wheel drive and hard mechanical locks of all differentials (interaxle and interwheel) will feel best. But in urban conditions, such cars do not give any pleasure from driving.

In turn, purely urban crossovers with their automatically connected all-wheel drive are practically helpless on any off-road, but they are controlled like ordinary cars.

The golden mean is permanent all-wheel drive, which will master off-road and will not give offense on the track.

But such a drive will not interfere with its work, that is, it may not be possible to save fuel or drive through a very difficult section (despite the “very smart” electronics).

At first glance, the principle of operation of the transmission of an all-wheel drive vehicle is simple: torque from power unit distributed between the four driving wheels. Such a machine is very convenient due to its pronounced advantages associated with unpretentiousness to the quality of the coating under the wheels. On a primer, in ice, on a wet countryside or on a highway in a heavy downpour, an all-wheel drive car will show itself at its best. Plus, on it you can not be afraid to move off the asphalt and cross the terrain without even a hint of the road, and on the pavement all-wheel drive makes itself felt good start and acceleration, with virtually no slippage.

But sometimes there are incidents that, it would seem, are difficult to explain due to the advantages that all-wheel drive vehicles have. It happens that the driver sits behind the wheel of an SUV with an impressive ground clearance, and the car got stuck in the "porridge" and lay on its belly.

Interesting to know! In 1883, the American farmer Emmett Bandelier patented a design similar to the current all-wheel drive system.

Of course, there can be many reasons for this, the most common of which, as experienced drivers jokingly say, is “gasket between the steering wheel and the seat.” But it also happens that the transmission of the "all-terrain vehicle" does not intend to cope with the tests. And then reasonable questions arise: “Why can’t it cope?”, “Which one can handle it?”. We will talk about this further in the material provided.

Manual all-wheel drive (Part-Time)

This type of transmission can rightly be called the "first-born" among all-wheel drive. The principle of its operation is the rigid connection of the front axle. Thus, all wheels rotate at the same speed, and the center differential is not provided. Torque is distributed equally between all wheels. Nothing to do in this case, so that the axles rotate at different speeds, will not work, except to infiltrate the “womb” of the car and mount a new differential.

In the meantime, it is not recommended to dissect in a car stream with a connected front axle. If you move even in low gear straight for short distances, nothing terrible will happen, but if you need to turn around, then the resulting difference in the length of the bridges becomes an obstacle. Since the distribution is 50/50% between the axles, the excess power comes out only by slipping the wheels of one of the axles.

On sand, gravel or mud, the wheels can slip if necessary, and nothing will interfere with them, since grip is weak. But if the weather is dry, and you are driving on an asphalt road, then there will be nowhere for the power to go, like off-road. Thus, the transmission is subjected to increased loads, the rubber wears out faster, controllability deteriorates and directional stability is lost at high speeds.

If the car is used more often off-road or generally purchased only for cross-country rides, then the all-wheel drive system with the forced connection of the front axle will fully meet your expectations. The bridge is connected immediately and hard, so you don’t have to block anything. The design is very simple and reliable, there are no locks and differentials, there are no drives of either electrical or mechanical type, there is no excessive hydraulics and pneumatics.

But if you're an urban dandy, value your time, and don't want to worry about the weather and the alternating sections of the city with its loose and slippery road surfaces, treacherous deep puddles, then this all-wheel-drive system option is absolutely not for you. If you move around with the front axle always forcibly connected, then this is fraught with wear and subsequent damage, it is not very convenient to constantly manipulate it, and in general you may not have time to connect it.

Cars with Part-Time: Suzuki Vitara, Toyota Land Cruiser 70, Great wall hover, Nissan Patrol, ford ranger, Nissan Navara, Suzuki Jimni, Mazda BT-50, Nissan NP300, Jeep Wrangler, UAZ.

Permanent four-wheel drive (Full-Time)

The disadvantages of plug-in all-wheel drive led to the creation of a newer invention - permanent all-wheel drive, which is devoid of all the problems that Part-Time had. This is the same uncompromising “4WD”, which is devoid of any “ifs” there: all the wheels are driven, there is a free differential between the axles, which releases the accumulated excess power due to the scrolling of one of the gear satellites, which contributes to the movement of the car with permanent all-wheel drive. The main nuance of cars with this type of all-wheel drive is slipping. If the car begins to slip on one axle, the second one is automatically turned off.

Now the car has turned into furniture or a house, as you wish, in general, into real estate. How does it happen? If one wheel begins to slip, the inter-wheel differential disables the second, and the second axle is also automatically disabled by the differential, but already the inter-axle one. Of course, in reality, the stop does not happen so quickly. Movement is a dynamic process, therefore, there is a power reserve, an inertial force. The wheel turns off, moves by inertia a couple of meters and turns on again.

But in this case, the car will stall somewhere sooner or later. Therefore, in order to preserve all the off-road qualities of the “rogue”, one or two forced locks of the center differential are usually installed on such cars. It is very rare to find a factory lock in the front differential. If desired, it is installed separately.

But the permanent all-wheel drive system is also far from ideal driving performance on paved roads. Such cars rulitsya, let's say, I would like it better. In critical situations, the SUV pulls out of the turn and it does not immediately respond to steering and gassing. Drivers of such vehicles require special skills and excellent vehicle feel.

To improve handling, they began to install interaxle self-locking differentials with a forced locking system. Different automakers used different solutions: some Torsen-type differentials, some viscous couplings, but the task for all is the same - improving the car's handling, and this requires a partial differential lock.

If one of the axles begins to slip, the self-locking mechanism is activated, and the differential does not affect the second axle, to which the torque continues to flow. A number of cars were also equipped with a self-locking differential mechanism rear axle, which had a positive effect on the severity of control.

Among cars with permanent all-wheel drive, one can distinguish Toyota Land Cruiser 100, 105, Land Cruiser Prado, Land Rover Discovery, Land Rover Defender, Lada 4x4.

Torque on-demand automatic all-wheel drive (AWD)

Time and the inquisitive minds of automotive engineers have done their job, developing the all-wheel drive system into something new with the introduction of electronically controlled systems with the redistribution and transfer of torque. As a result, stabilization systems appeared and exchange rate stability, traction control systems, as well as systems that distribute torque. All of them are implemented using the involved electronics. The more expensive the cost of the car and the more modern its filling, the more complex schemes are applied to it.

This is tracking the steering angle, body roll and speed, up to how often the wheels oscillate over a certain distance. The car carries out the most complete collection of information about its behavior while driving. The ECU processes it and regulates the transmission of torque between the axles through an electronically controlled clutch that has replaced the differential. On modern sports cars this invention has become very worthy of attention.

To date electronic systems can be called almost ideal in their behavior. It only takes manufacturers to add a few new sensors and parameters that make the system proactive.

But even here there are some nuances of use: this type of all-wheel drive transmission is suitable for operation only on asphalt roads with occasional interspersed with symbolic off-road, primer, for example. Basically, electronic clutches, when slipping off-road, begin to get very hot and fail. And for this you do not need to plow tank tracks for hours, ten minutes of skidding on ice is enough. And if it is systematically overheated, then damage cannot be avoided, as well as costly repairs.

The "cooler" the system, the more prone it is to breakdowns. So you need to choose a car wisely, having determined for yourself which tracks you will ride it on. Do not go to extremes: if an SUV, then only in the forest and in the village, and if a passenger car, then only in the city. There are plenty of cars from this segment that are versatile in their driving characteristics. But also without fanaticism, too. On the passenger car you can, of course, go to a country road, but which one and which one is another question.

If the wiring breaks on one of the ABS sensors, the entire system will fail at once and will not receive information from the outside. Or filled with gasoline best quality- and that's it, the downshift does not turn on, there is a trip to the car service ahead. Or it may happen that the electronics will put the car into service mode, completely turning off all the systems of its life.

Among these vehicles, it is worth highlighting Kia Sportage (after 2004), Cadillac Escalade, Nissan Murano, Nissan X-Trail, Ford Explorer, Toyota RAV4 (after 2006), Land Rover Freelander Mitsubishi Outlander XL.

Multimode (Selectable 4wd)

This system is perhaps the most multifunctional in relation to all-wheel drive with its various manipulations: it can be activated manually or automatically, as well as forcibly disabling the rear or front axles. Using the Selectable 4wd system does not increase fuel consumption. The leaders in fuel overruns are the cars with part-time mentioned at the beginning.

Some cars with a selective transmission, which can be called permanent all-wheel drive, with the ability to forcibly turn off the front axle, stand apart. On such vehicles, the transmission combines part-time and full-time. Among them Mitsubishi Pajero, Nissan Pathfinder, Jeep Grand Cherokee.

In Padzherik, for example, you can choose one of several transmission modes: 2WD, 4WD with automatic center differential lock, 4WD with hard differential lock, or downshift. As you can see, here you can find references to all the above all-wheel drive systems.

Some front-wheel drive cars may have a leading rear axle. A small electric motor is mounted in the final drive housing, which is connected at the request of the driver - the e-4WD system. The electric motor is powered by a car generator. Such a system improves the controllability of the car on the track in a downpour, and also helps to pass snowy, icy and muddy sections of the road with confidence. A prominent representative of cars with this system is latest models bmw.