Which drive is better? Car drive: which one to choose? Four-wheel drive: pros and cons, as well as varieties of all-wheel drive cars.

Very often, motorists argue about which type of drive is better. Let's look at the advantages and disadvantages of each type separately.

Rear drive

Let's start with rear-wheel drive, which is considered classic, this is due to the fact that for a very long time cars had rear-wheel drive and a longitudinally located front engine.

Disadvantages of rear wheel drive:
1. Expensive in production, which is reflected in the final price of the car.
2. Cars with a rear-wheel drive type are heavier; as a rule, they always have a tunnel located in the center of the body, which eats up the useful volume of the passenger compartment and reduces the comfort of the rear passengers.
3. Traction in snow and mud conditions is worse than that of front- or all-wheel drive vehicles.
4. Tendency to skid the rear axle of the car.

Front drive type

The engine is mounted transversely relative to the axis of the vehicle.

Front wheel drive benefits:
1. Cheapest to manufacture.
2. Due to lack cardan shaft as a rule there is no central tunnel (but is present if the car has an all-wheel drive version).
3. High permeability on snow and mud, congenital good directional stability.
4. Lower vehicle weight.

Disadvantages of front-wheel drive:
1. Vibration from the motor due to rigid mounting is transmitted to the body.
2. The steering wheel during intensive acceleration transmits reactive forces (expressed in the form of shocks). Therefore, front-wheel drive vehicles with a capacity of more than 250 hp. as a rule, they are not released due to the inability to realize the potential of the engine.
3. With a sharp start, the weight is redistributed back, the front axle is unloaded, and the drive wheels tend to slip.
4. Demolition of the front of the car.

Full drive type

All wheels are driving, which provides good directional stability and cross-country ability. There are several types of all-wheel drive, permanent or plug-in.

Constant four-wheel drive

When the vehicle is equipped with a permanent four-wheel drive system, torque is continuously transmitted to all wheels. The car has a constant readiness for difficult traffic situations, the disadvantages can be considered the highest fuel consumption and difficult to technical terms construction.

Plug-in all-wheel drive

This type of drive involves driving in normal modes in a single-wheel drive (more often rear-wheel drive) mode with the connection of an all-wheel drive system only when necessary. The advantage is low consumption fuel, a higher level of comfort, the disadvantage is increased transmission wear and poor handling when the all-wheel drive system is on, since the front and rear axles will move at different angular speeds and forces that are not compensated by anything.

Automatic all-wheel drive by type - traction on demand

The type of drive when the automation connects the second axle when the first one slips by blocking the center clutch. There are two types of plug-in drive - with a viscous clutch, which is cheaper, but does not provide a timely connection of the axle, that is, the car can get stuck or go off the path, or with a multi-plate clutch, which is more expensive, but provides a more efficient connection of the second axle, since closes much faster and allows you to accurately distribute thrust along the axes in real time.

An example is the xDrive system installed on bmw cars, the center clutch of which constantly redistributes the torque, taking into account the readings of many sensors. For off-road driving, such systems are equipped with differential locks, upon activation of which the thrust is divided along the axes 50 * 50. The advantage of this system is low fuel consumption, more enduring technical component, the disadvantage is the cost and complexity in production.

Advantages of all-wheel drive:
1. High course stability.
2. Better car handling.
3. The best cross-country ability among all drive types.
4. The most efficient start from a standstill, especially in low grip conditions.

Flaws complete type drive:
1. The most expensive to manufacture, repair and maintain.
2. Enhanced Level noise due to two cardans.
3. The central tunnel creates the same disadvantages and inconveniences as the rear-wheel drive.
4. High weight and increased consumption fuel.
5. When a critical situation arises on the road, the car slides on all four wheels, which makes it much more difficult to return it to the driver's control.

The type of vehicle drive is determined depending on which wheels are leading in the transmission design. There are three main layouts: rear-wheel drive, front-wheel drive and all-wheel drive. The constructive solution of engineers plays big role in the control concept and influences the dynamics of the machine as well as other characteristics. The first cars were equipped exclusively with a rear chain drive when placing the engine in the center. Machines with longitudinally installed motor, gearbox, cardan shaft and drive rear axle, but the complexity of the design gave rise to the search for engineers for more simplified implementation schemes.

Comparison of rear and front wheel drive vehicles.

The advent of front-wheel drive cars has become a new milestone in the evolution of the automotive industry. Ease of execution led to lower production costs, and in the fifties and sixties, front-wheel drive cars became widespread. Ease of control, compactness, relatively low cost of cars in which torque is transmitted to the front wheels ensured the wide popularity of such models.

The debate about which type of drive is still better does not subside even today, but it is impossible to come to a consensus due to the relevance of the advantages of each of the design solutions depending on the operating conditions. Despite the worldwide popularization of front-wheel drive models and their many advantages, the leading automakers BMW, Mercedes and other equally respected concerns do not depart from the classic design, implemented through the rear-wheel drive scheme, which says a lot. It is almost impossible to notice the difference in handling on flat city roads, but all the advantages and disadvantages can be felt under certain conditions.

Progress in equipment equalizes rear-wheel drive and front-wheel drive cars with. Modern equipment of machines that meet reliability parameters allows minimizing the risks of loss of control in emergency situations, but here the experience and composure of the driver play the leading role. Virtuosos of emergency driving are able to keep any car on the road, regardless of the type of drive and the number of options.

Rear drive

car transmission design rear wheel drive(RWD) provides torque transfer from the engine to rear wheels, which are leading, due to them the movement is carried out. It is impossible to say unequivocally which is better - a rear-wheel drive or a front-wheel drive car. When choosing a model, it is necessary to take into account the nature of the operation and the driving skills of the motorist. During acceleration, the weight of the car is transferred to the rear axle, loading the rear drive wheels and unloading the front ones, as a result of which traction improves, engine power is used more efficiently, and the wheels slip less.

The rear-wheel drive device provides variability in the location of the engine. The transmission includes a clutch, gearbox, differential, axle shafts, cardan and final drive. A front-wheel drive car does not have as many system elements, is famous for its ease of operation with minimal driving skills, and is more affordable than it also differs from a rear-wheel drive car. However, when buying a car executive class or racing, the choice of the classic version of the design will be relevant.

Advantages of rear-wheel drive designs:

good dynamics of acceleration of the car;
the behavior of a rear-wheel drive car is more predictable, drifts occur at a lower speed than a front-wheel drive;
getting out of a skid on a car with RWD is much easier: it is corrected by releasing the gas (unlike front-wheel drive) or turning the steering wheel in the direction of skidding while holding the clutch, braking in this case is unacceptable;
Less vibration is transmitted to the steering wheel power unit;
the maximum steering angles are larger and the turning radius is smaller. The front wheels set the direction, while the rear wheels, to which the power of the engine is transmitted, push the car. This is the reason for the ease of entry into turns, a confident rise;
the ability to use different control techniques, including controlled drift, which is not feasible for a car with front-wheel drive;
uniform tire wear;
the implementation of the drive can be with a very different arrangement of the motor and other transmission elements;
ease of access to units Maintenance due to their uniform distribution.

Disadvantages of rear wheel drive:

the production of cars with RWD is more expensive, as a result of which the final price tag is higher, budget models are equipped with front-wheel drive;
increased total weight of the car due to a larger number of structural elements;
with any layout, the interior space is stolen (by a cardan tunnel or motor);
larger ;
the complexity of the design of the rear axle, the need to monitor the condition of the bridge and timely maintenance;
more likely to burrow in snow or mud.

Front-wheel drive

The main difference between rear-wheel drive and front-wheel drive vehicles lies in the design of components and assemblies. The torque generated by the engine is transmitted to the front wheels, resulting in good directional stability. Front-wheel drive (FWD) cars are lighter and more compact, and assembly is easier and cheaper, which is why most automakers produce models in this design option. Thanks to the accumulation of units in one place, it was possible to achieve increased interior space. In cars with FWD, all transmission elements are united by one unit, the gearbox also includes a final drive with a differential, and the front-wheel drive shafts come out of the gearbox housing.

The design difference implies a completely different principle of machine control. If for rear-wheel drive cars skidding is a common thing, then in order to skid a front-wheel drive car, you need to try. However, this is the danger, since poor traction during ice is not so noticeable to the driver, but to get away from skidding on front wheel drive much more difficult. Drivers who switched from "classic" to a front-wheel drive car often make the mistake of trying to level off without taking into account physical properties designs.

The principle of behavior in the event of skidding is fundamentally different. In front-wheel drive, you can’t slow down, or rather, on the contrary, you need to add gas and maintain speed until the car’s trajectory stabilizes, unlike rear-wheel drive, where you need to release the gas. Intuitively, the driver releases the pedal, but here it is necessary to take into account the features of the transmission, following the rules for driving a car with different types drive. Parking in a front-wheel drive car is much more convenient, because the drive wheels turn in the direction of the turn, which allows you to set a clear direction. Patency due to the increased load on the front wheels is better than that of rear-wheel drive vehicles.

Front wheel drive benefits:

cars are cheaper to assemble, respectively, the price will please the end consumer;
due to the fact that the drive wheels are also steering wheels, while slippage is reduced due to the pressure of the engine weight on the front wheels;
stable course on slippery road surfaces;
on a slippery slope, a car with FWD rises better: the front wheels, despite slipping, drag the car when the steering wheel is turned and the gas pedal is pressed, a rear-wheel drive car will turn around during such maneuvers;
ease of management, ease of parking;
it is more difficult to start a car into a skid, but at the same time it is also more difficult to get out of it;
interior space due to compactness engine compartment and the absence of a cardan shaft;
lighter weight, compact car;
economical fuel consumption.

Cons of front-wheel drive systems:

tangible vibrations in the cabin, especially when equipped with a diesel engine;
during acceleration, reactive forces are transmitted to the steering wheel, it begins to tremble;
larger turning radius;
the car has less maneuverability;
lack of proportional weight distribution due to the accumulation of units in the front;
when skidding, it is more difficult to keep the car, in order to level out, considerable skill of the driver will be required;
drifting on a front-wheel drive car will not work.

As a conclusion

When choosing a car, it is necessary to take into account the driving experience and operating conditions, it is impossible to specify which car is better - rear-wheel drive or front-wheel drive, despite the fact that the advantages of one type are manifested in the shortcomings of another. For beginners, it is better to choose a car with front-wheel drive, it will also be a good option if you are planning to forays onto a dirt road outside the city.

Rear-wheel drive cars are more suitable for drivers with good driving skills, will be interesting to drive, and will also provide an opportunity to have fun through controlled skids. In winter, RWD models require attention from the motorist, but this does not mean that they are less safe than front-wheel drive models, which have stable stability and handling parameters. Provided that the car is equipped with anti-slip control ESP system, on studded tires it will be equally successful to climb a slippery slope with any type of drive.

If you buy a bolivar for practical reasons, the optimal front-wheel drive car is more affordable and economical. Cars with rear-wheel drive accelerate perfectly, easily enter a skid, but also get out of it without problems. In terms of cross-country ability, front-wheel drive cars are better, but you still should not get out on the road with either RWD or FWD. So, cars with different types of drive have their advantages and disadvantages, depending on the nature of driving, driving experience motorist and expected operating conditions.

Complete off-road driving is not applicable with any of these transmission options. For this, there is a separate class of cars - SUVs equipped with all-wheel drive, where all wheels are driving. Permanent, connected manually or in automatic mode all-wheel drive provides better cross, but machines of this type are quite "gluttonous", therefore, when choosing, it is important to consider models that correspond to the intended operating conditions.

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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 is different models can differ significantly. All types of all-wheel drive can be divided into three main types: 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.Full Drive Part Time can be forced to connect only to overcome a difficult section of the road at low speed. Usually, the transfer case lever is used to connect. 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.

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.

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Which drive is fuller? 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. he won’t let himself be offended on the highway. 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).

Part time

This type came first. It is a hard connection diagram of the front axle. That is, front and rear wheels always spin at the same speed. There is no center differential.

A differential is a mechanical device that accepts torque from drive shaft and distributes it between the drive wheels proportionally, automatically compensating for the difference in their rotational speed. We can say that the differential sends torque to the drive wheels, allowing them to rotate with different / differentiated angular velocities(hence the name itself - differential).

Differentials are in the front and rear axles on all vehicles equipped with all-wheel drive. On some machines, the differential is also used in transfer case(This all-wheel drive scheme is called full-time, we will talk about it a little later).

Let's try to figure out why a differential is needed. The wheels of any car rotate at the same speed only when the car is going straight. As soon as she starts turning, each of the wheels begins to live its own life. One of the wheels of each bridge starts spinning faster than the other, and the bridges themselves compete with each other in speed. This is due to the fact that the wheels go on different trajectories. The one on the outside of the turn travels a longer distance than the one on the inside. So are bridges. Accordingly, the inner wheel (or the axle to which it belongs), if it were not for the differential, would simply turn in place, compensating for the movement of the outer wheel.

It is clear that about no riding with high speeds In this case, you can't speak. The lack of control will not allow this, and the load on the transmission will quickly disable it, not to mention prematurely worn tires. The differential just allows one axle to overtake another when there is a difference in their speeds.

Part-time does not have a center differential, the moment on the axle is transferred equally, the rotation of the axles at different speeds is impossible, so driving with the “front end” connected on paved roads is highly discouraged. With a short rectilinear motion even in low gear, nothing bad will happen (you can pull the cart with the boat out of the lake). But when you try to make a turn, the same difference in the lengths of the bridge paths arises. Remember that the moment is transmitted in the same way - 50/50, and there is only one way out of its excess: slippage of the wheels of the front or rear axle on one of them.

In mud, sand or gravel, nothing prevents the wheels from slipping if necessary due to the low grip of the wheels on the ground. But on the pavement in dry weather, the output of this power is realized in exactly the same way, which entails an increased load on the transmission, rapid wear of rubber, deterioration in handling and directional stability at high speeds.

If the car is needed mainly for off-road, and it is not planned to use all-wheel drive on asphalt, part-time will fully justify itself, since one of the bridges is immediately connected hard, nothing needs to be blocked. And the design is simpler and more reliable: there is no differential and locks, there are no mechanical or electric drives to these locks, there is no extra pneumatics or hydraulics.

But if you just want to calmly ride on asphalt in any bad weather and not worry about alternating icy and clean asphalt sections, snow drifts, water-filled lanes or any other slippery-loose-unpleasant areas, part-time is not the best option: if you drive with the front axle constantly on, then this threatens with damage or wear, turning the axle on and off is not very convenient, and you may not have time to turn it on.

Cars with this type of all-wheel drive: Toyota Land cruiser 70, Nissan Patrol, Nissan Navara, ford ranger, Mazda BT-50, Nissan NP300, Suzuki Vitara, Suzuki Jimni wall hover, Jeep Wrangler, UAZ.

Full time

The existing shortcomings of the plug-in all-wheel drive led to the creation of a permanent all-wheel drive, devoid of these problems. This is the same cherished “4WD” without any “ifs”: four driving wheels with a free center differential, which allows the resulting excess power to come out due to the scrolling of one of the internal satellites in the gearbox, and the car always rides on all-wheel drive.

The main nuance of this type of all-wheel drive is that the slip of one axle automatically turns off the second axle, and the car turns into real estate. What does it mean? In general, the situation is as follows: one wheel stalled, the cross-axle differential turned off the second wheel of the axle. Accordingly, the second axle is also automatically switched off by the center differential. Of course, in real life, the stop does not happen so quickly. Movement is dynamics, which means there is some kind of power reserve, inertia, the wheel turns off for a moment, slips a couple of meters by inertia and turns on again. But as a result, the car will still get up somewhere.

Therefore, so that the cross-country ability of the SUV does not deteriorate, such cars often have at least one forced blocking ( center differential), and at most two. Locking in the front differential is regularly installed quite rarely. But if desired, it can most often be installed separately.

Cars are in a separate category. Mitsubishi Pajero(Super Select 4WD transmission), Jeep Grand Cherokee(SelecTrac) Nissan Pathfinder(All-mode 4WD), Land Rover(Terrain Response). Their selective transmission can be called a permanent all-wheel drive system (automatically connected in the case of the Nissan Pathfinder) with the possibility of forced disengagement of the front axle. That is, on these machines, the transmission, let's say, combines part-time and full-time.

Vehicles with permanent all-wheel drive include Toyota Land Cruiser 100, 105, Land Cruiser Prado, Land Rover Discovery, Land Rover Defender, Lada 4x4.

Permanent four-wheel drive in its classic version is also not without drawbacks when driving on asphalt. Handling of such machines leaves much to be desired. In the event of critical situations, the SUV tends to slip out of the turn, sluggishly reacting to the work of the steering wheel and gas. From the driver of an SUV with permanent all-wheel drive, some skills and a good sense of the car are required.

To improve handling over time, center differentials began to be used, which, in addition to forced blocking, also have a self-locking mechanism. Various manufacturers used different solutions: someone was a Torsen type differential, someone was a viscous coupling, but they had one task - a partial locking of the center differential for better handling.

At the moment of slipping of one of the axles, the self-block is activated and does not allow the differential to turn off the second axle, so the torque continued to flow to it anyway. On a number of cars, a self-locking differential was also installed on the rear axle, which made the car sharper on the steering wheel (for example, Mitsubishi Pajero).

Torque on-demand (AWD)

Further improvement of permanent all-wheel drive has led to the emergence of electronically controlled systems with the transfer and redistribution of torque.

The result of all this evolution was the system of exchange rate stability, stabilization, traction control and torque distribution systems, which are implemented electronically. These systems receive signals from ABS sensors that monitor the speed of each individual wheel. The more expensive and more modern car, the more complex schemes can be used on it: tracking the steering angle, rolls of the car body, its speed, up to the frequency of vibration of the wheels. The car completely collects all the information about its behavior on the road, and the computer processes it and, based on this, regulates the transmission of torque to one or another axle through an electronically controlled clutch that replaced the differential.

Such all-wheel drive transmissions are called torque on-demand (literally - torque on demand). On modern high-speed cars this invention is very noteworthy.

Early schemes (twenty years ago) could sometimes behave not quite adequately, there were cases with a strong delay in the operation of the clutches (when the second axle was suddenly connected in the turn), because at the first stage of development, the clutches worked in fact. The speed of signal processing from sensors and the redistribution of torque depended on the time it took for these signals to reach the brain of the machine. Modern technologies data transmission, optical fiber and powerful processors that process information instantly - all this has negated the initial shortcomings. Now electronic systems practically do not have serious flaws in behavior, with the addition of new sensors and new parameters, they almost always work ahead of the curve.

But there is one “but”: this type of all-wheel drive transmission is suitable only for operation on asphalt with episodic minimal off-road like moderately broken primer.

Most electronic clutches are not designed for off-road use; when slipping, they overheat and simply stop working. Moreover, for this you do not need to knead the track for half a day, ten minutes of ice drift, beloved by many, may be enough. And if you overheat it regularly, it can completely fail.

Almost all systems use brake mechanisms machines for braking slipping wheels, and dirt and sand, inevitable on the roads, greatly contribute to the rapid wear of the pads and brake discs, which, in addition to the cost of new spare parts, has a bad effect on the brakes themselves.

The more sophisticated the system, the more vulnerable it is, so you need to choose a car wisely, realizing that even purely urban cars, designed for asphalt, quite allow exits to country roads. But you need to understand which ones. An accidental break in one wire of the ABS sensor will disable the system, because it will no longer receive information from the outside. Or fuel of not very high quality will come across - also a trip to the service, because the “lower” may no longer turn on. Other "electronic brains" can generally turn off the machine and put it in service mode.

Vehicles with torque on-demand - Cadillac Escalade, Ford Explorer, Land Rover Freelander, Toyota RAV4 (after 2006 onwards), Kia Sportage(after 2004 onwards), Mitsubishi Outlander XL, Nissan Murano, Nissan X-Trail.

In conclusion, I would like to give a simple advice: if you choose a car only for off-road, then part-time will become great option. If we are talking about movements mainly in the city, then AWD will be quite enough. Well, a permanent full is good in any situation.

At first glance, the principle of operation of the transmission of an all-wheel drive vehicle is simple: the torque from the power unit is distributed between the four drive 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 all-wheel drive vehicle will show himself at his best. Plus, you can not be afraid to drive off the paved surface and cross the terrain without even a hint of the road, and on asphalt, all-wheel drive makes itself felt with a 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 American farmer Emmet 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 bad 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 are an urban "dandy", value time and do not want to bother about weather conditions and alternating sections of the city with its loose and slippery road surfaces, treacherous deep puddles, then this option all-wheel drive system absolutely not right 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 "if" there: all wheels are driven, between the axles there is a free differential that releases the accumulated extra power due to the rotation 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, cross-axle differential disables the second, and the second axle is also automatically disabled by the differential, but already the center 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. So to save everything off-road qualities"rogue", such cars, as a rule, install one or two forced blocking center differential. 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 - to improve 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 and exchange rate stability systems appeared, traction control systems, as well as systems that distribute torque. All of them are implemented using the involved electronics. How more expensive cost car and its filling is more modern, 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 here there are some nuances of use: given type all-wheel drive transmission is suitable for operation only on asphalt roads with rare interspersed 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 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 are 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. To the body main gear a small electric motor is mounted, which is connected at the request of the driver - the e-4WD system. The electric motor is powered by car generator. Such a system improves the controllability of the car on the track in a downpour, and also helps to confidently pass snowy, icy and muddy sections of the road. A prominent representative of cars with this system is latest models bmw.

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