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 a classic, this is due to the fact that it is very for a long time cars had rear 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. Vehicles with rear type the drive is heavier, they, as a rule, always have a tunnel located in the center of the body, which eats up the usable 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 rear axle auto.
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 snow and mud flotation, inherent good directional stability.
4. Lower vehicle weight.
Flaws front type 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. When abrupt start there is a redistribution of weight 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 complex traffic situations, the disadvantages can be considered the most high flow fuel and technically complex design.
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 fuel consumption, more high level comfort, disadvantage increased wear transmission and poor handling when the all-wheel drive system is on, since the front and rear axles will move with different angular velocity and effort that is 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 would be 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 similar systems 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.
Disadvantages of the full drive type:
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 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 may differ significantly.
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 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.
Only “full-fledged” SUVs that are used for their intended purpose are equipped with temporarily connected all-wheel drive. Outstanding representatives such "rogues" can be called and who are in no hurry to give control of all-wheel drive to electronic "brains".
In addition, “temporary” all-wheel drive is equipped with almost all Chinese copies famous SUVs 90s.
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.
Thanks to the presence center differential such a transmission constantly (under any conditions) operates in all-wheel drive mode. Moreover, in modern models the center "diff" has its own electronic "brains".
With such a differential, the 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 road surface (asphalt, gravel, sand, etc.), the driver only needs to press the desired button.
The most famous representatives of permanent all-wheel drive is a company with a proprietary Quattro system, and Subaru with AWD system (All wheel drive).
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 of 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).
Wherein electronic system stabilization (ESP) allows you to maintain control of the car, which can suddenly change 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. New type of car demanded new type 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 interlocks all differentials (interaxle and interwheel). 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, neither save fuel, nor after a very difficult area drive (despite the "very smart" electronics) may not work.
Why do we continue to talk about car drives, today we have a global topic, namely, what is better and what to choose front or all-wheel drive for an SUV or crossover? As you and I know, it is not entirely honest there, that is, it is not permanent and often does not have a hard differential lock, that is, you cannot manually lock it, it is connected only after the front axle starts to slip. And now a completely fair question arises - “is it necessary or front axle enough for the eyes? Everything is not clear here, let's understand ...
Well, to say in general — that four-wheel drive is bad, I will not! Still, I think that quite the contrary, it's even good! There are big and heavy vehicles, where he works constantly, which greatly improves cross-country ability. There is not much big cars, middle class "C", sometimes "D", where it is also constant or hard-wired (which improves both cross-country ability and handling under certain conditions), but SUVs or crossovers are completely different. All-wheel drive in them, unfortunately, has now become the property of marketers and businessmen, that is, they are trying to prove to you that they are “digging” four wheels, but in the end everything turns out completely wrong. In this article I will try to debunk all the myths, but for a better understanding, you need to talk about each type, and I think it’s worth starting from the front.
As we have already said, there are also many “copies broken” about this topic, but there the principle of talking is different, yet one driven axle is either front or rear, today the essence of the issue is different.
The front-wheel drive is very simple in structure, and it is now practically brought to perfection, that is, it can go for a very, very long time without any breakdowns.
Device :
- Engine
- Attached to the engine gearbox with differential, often in the same housing
- From the box (differential) there are two axles with. Each side has two CV joints (inner and outer)
- These CV joints fit the front wheels through special hubs.
Torque is transmitted from the engine - transmission - axles - wheels. This is how it is given front wheel drive car in motion.
It is worth noting that transmission fluids there is not much here, that’s all in the box itself, as a rule, the rest of the joints are dry (well, or almost dry, there is grease under the anthers in the CV joints, but there it’s really minuscule and it doesn’t change). This tells us that you can not follow this design at all. Of course, I still advise you, because if they break, the hinge will soon fail, but believe me, for the next 70 - 80,000 km, this can not be done. If the manufacturer is serious, then anthers can walk 150 - 200,000 km.
The rear suspension in the front drive does not carry any semantic load, that is, it is a banal “support for the wheels”, there is practically no weight, it is light here (either a beam or a “multi-link”). And more importantly, rear end requires virtually no maintenance, well, unless brake pads change.
Four-wheel drive
Even a plug-in all-wheel drive through a viscous coupling has a much more complex structure (I'm already silent about the permanent ones). There are more parts that spin (most of the time) at idle, there are already two bridges, not one, also appear cardan shaft and the rear axle is no longer secondary.
Device :
- Engine
- A gearbox that can be combined with a front differential. However, the front differential can be taken out separately
- Front axle with CV joints for front wheels
- Center differential, it can also be in the same housing with the box, but it can be separate (it all depends on the design)
- Transfer case.
- Rear cardan to transmit torque to the rear axle
- Visco coupling or electro coupling (hydromechanical) for automatic connection rear axle
- Rear axle. It can be made in a cast case, from which two axle shafts extend to rear wheels. But now often two axles with CV joints also go from the rear differential, by analogy with the front axle.
As you can see, the structure is much more complex! Two more differentials appear here, center and rear, there is also a transfer case, viscous couplings and more. All this adds to the weight of the car at least 100 kg, and possibly more. There are also a lot of parts that are "spinning" in oil, and they really need to be monitored. Some manufacturers recommend changing them transmission oil. If any oil seal leaks, the whole assembly may fail. I think everyone understands this, but again, everyone thinks since I have all-wheel drive, then I’m on some SUV or crossover, on a RAV4 or the same Duster, I’ll just become an off-road conqueror - “what do I need an UAZ, I myself am like an UAZ” ! BUT is it really?
Four-wheel drive through a viscous coupling (electric coupling, hydromechanical coupling)
Well, here we come to the most interesting thing, for whom is the all-wheel drive of such crossovers, where can it be used? For many, this means that you can immediately go to the forest for mushrooms and berries, that you can fight such impassability, that, as they say, “on the door”! Guys, stop, all-wheel drive on crossovers and SUVs is very conditional, I would even say “urban” it is not intended for serious off-road tests.
Why? Yeah, it's just not designed for it. Often, on many crossovers, it is connected through a viscous coupling or an electric coupling.
- viscous coupling , we have already talked about it (you can in detail). Transmits torque through special liquid enclosed in the viscous coupling housing. When one axle begins to slip, the fluid quickly hardens, thereby closing the rear axle and connecting it. The disadvantages of such a drive are that it is almost impossible to turn it on yourself or block it rear differential to work. ONLY AFTER SLIP. Therefore, the efficiency of such a full drive is quite low.
- As it becomes clear, the work is a little different. There is no special liquid here, but there are electromagnets that close or open the disks when voltage is applied to them, thereby connecting or disconnecting the all-wheel drive. This clutch is dry, there are no oils in it, which is both good and bad. The good thing is that you do not need to monitor the leakage of seals and change the fluid. Bad - this clutch overheats quickly. All-wheel drive is connected after front-wheel drive slips, usually after the second rotation of the front wheel. In some vehicles equipped with such a node, there is forced blocking, that is, you can physically block the rear axle. It seems that here it is the DECISION, the control is much better than that of the viscous coupling, HOWEVER, THERE IS A BIG FLY IN THE OIL. Such a drive overheats very quickly and turns off, if you can slip for a long time on a viscous coupling, then here electromagnetic clutch, will turn off after 3 - 5 minutes of slippage. They also fail faster due to high temperatures, as the experts say - they just burn.
- Hydromechanical clutch. Very similar design with the electromagnetic version. However, here the discs are closed due to oil pressure. Inside there is a pump that creates pressure to compress or unclench them. The pumps are now also available with electric drive, used to be mechanical.
In fact, such structures are used in in large numbers crossovers or SUVs, it’s very, very difficult to find another here.
Full or front?
As you can see, to call such all-wheel drive - COMPLETE, somehow the tongue does not turn! What are they made for. You know, I once talked with a "hardened" mechanic about such automatic connections, and this is what he told me - “poking into even (medium dirt) on such machines will be expensive, they are simply not designed for this off-road, do not think that you bought a car similar to our UAZ in cross-country ability, THESE ARE DIFFERENT CLASSES! Especially if you have automatic transmission gears, because it can also overheat quite quickly (everything is a little better with mechanics). These cars are designed to deal with a snow-covered yard in the city in winter, or with a couple of shallow puddles on the way to the country house"
You know this like a shovel in your trunk or a neighbor is a passenger - what do I mean? On a front-wheel drive car, you will need to clear the rut in front a little (with a shovel), or ask a passenger next door to give you a little push. But such a plug-in all-wheel drive car will be able to get out by itself. Fine? Of course yes! But is it worth paying extra for it?
If you disassemble the front and full options, you should think about where and how you move? It is also worth considering that an all-wheel drive vehicle:
- Costs more.
- Complete sets with all-wheel drive are at least "medium" and "top", that is, you will not find it in the "standard".
- The car weighs more
- More vibrations. Because more knots are spinning.
- Service costs more
- More rotating elements, which reduces the resource
- More fuel consumption
- The modest capabilities of this all-wheel drive car
Actually, if you are a 100% city dweller, the snow is removed in the cities, you go to the country house where there are several meters of dirt that are not quite comfortable - THEN TAKE SUCH ALL-WHEEL DRIVE, AS I THINK THIS IS OVERPAID, AND IT IS NOT NEEDED!
A four-wheel drive car is now taken for granted: all-wheel drive, allegedly, provide great safety on the road and self-confidence. That is why, if there is money, we buy all-wheel drive crossovers for ourselves and for our wives. However, there are quite a few all-wheel drive systems, even in the first approximation, and they are fundamentally different from each other.
When choosing a car and aiming for “all-wheel drive”, you need to have a very good idea of where and why the car will be used. Probably, 90% of buyers are not going to move off the normal road into forests, fields, as well as climb mountains and cross fords. Why do you need a car with all-wheel drive? Firstly, it gives confidence during the rain on slippery road; secondly, they buy a car with an eye to long winter operation; finally, with all-wheel drive it is easier to get off the asphalt and drive half a kilometer to the dacha on a dirt road and over bumps.
The simplest thing to remember and then close this article: the above three tasks are completely solved by a car with a drive on only one axle. It is desirable, however, that he be with mechanical box gears. Well, more clearance would be nice.
Let's say this solution to the problem does not satisfy you. Then the second consideration: all-wheel drive crossover is not at all equal to a real SUV. The wheels of these cars are set in motion, let's say, fundamentally different ways. And third: yes, the indicated need for all-wheel drive can be met by buying a crossover. It’s just that you don’t need to travel on real off-road on such a car. And on the road - do not get carried away with speed.
So, how in in general terms arranged all-wheel drive crossover. Almost always you drive such a car in ... mono-drive mode, only one axle works for movement. Most often - the front, because almost everything is not too expensive crossovers built on the platforms of conventional hatchbacks. Four-wheel drive appears only in a situation of slipping of the drive wheels - this moment is recognized by the electronics, which connects the second axle to help. slip in this case does not mean that you stand still and grind the asphalt for a long time - we are talking literally about milliseconds. It is unlikely that the buyer is interested in technology, let's just say that the transfer of torque between the axles - and it is dynamically distributed at every moment of time - is handled by a special clutch. This device itself can have a different design.
Now about off-road abilities: if the scheme is fully consistent with the description above, there are practically none. To overcome the minimum off-road, you have to "hang" additional functionality. For example, the clutch is given the ability to partially or completely block. The methods may be different, but, again, most often this is in charge of electronics. Also, a self-locking differential or a viscous coupling can be used in the design.
Why is blocking necessary? A free clutch (or free differential) will prevent the car from moving if one of the wheels completely loses traction. And blocking will make spinning the wheel that is still able to pull you out. In this case, the clutch overheats very quickly, so you won’t be able to slip with such a system for a long time.
As with any design, there are many nuances. The main one is that the clutch in the advanced automatic all-wheel drive can work according to a preventive algorithm, without waiting for the wheels to slip. Here, a small percentage of torque will always be supplied to the second axle. In other words, you really get permanent four-wheel drive! This is how they work Audi systems with a Torsen differential, as well as, for example, some BMWs or Mercedes-Benz.
We repeat: almost all crossovers and all-wheel drive have a similar type of all-wheel drive. cars. Pros: indeed, the car gives some confidence on slippery roads. Cons: This same confidence can cause you to choose the wrong speed for driving in difficult conditions. The result may be a curb. Also because the nature of such a car is in a turn - it will be inclined precisely in this dangerous moment to demolition or skidding, or it will be neutral - it is quite difficult to predict. As well as to give the car "off-road", controllability is improved with the help of electronics - the main auxiliary system ESP here.
Now - about off-road all-wheel drive. Here the second axle is connected manually by the driver. On the way, you drive on a monodrive, and if you need to move to some problematic area, you turn on the full one yourself. There is no inter-axle differential, so the locking of one of the inter-wheel differentials must be present. And, of course, all-wheel drive with such a scheme must be immediately turned off on the road - it is not designed to work at high speeds.
Finally, a classic of the genre - an honest four-wheel drive. Ideally, these are not just three differentials - an interaxle and two interwheels, but also a downshift and all locks. And, of course, auxiliary electronics. With such a set of properties, the car, indeed, can both stand on the road and overcome impassability.
We will separately mention extremely advanced systems: for example, Super Select Mitsubishi allows you to choose from many modes of operation of the all-wheel drive such that it is suitable for both the track and off-road. Some Jeep models can be ordered with significantly different types of all-wheel drive. Finally, the systems Subaru Impreza WRX STi or Mitsubishi Lancer evolution Each is worthy of a separate large article.
Arguments about whether a car with which drive is better to choose, rear, front or all-wheel drive, belong to the category of disputes about which gearbox is better - manual, robotic or automatic, or about the advantages gasoline engine over diesel and vice versa.
But since motorists exaggerate the topic of the drive from year to year, it means that not everyone has yet realized what are the advantages and disadvantages of each of the mentioned transmissions. In this article we will talk about the pros and cons of front, rear and all-wheel drive, and let the reader, based on our arguments, make the choice for himself - a car with which transmission suits him best.
Choice #1. Rear drive
If you just list the brands that produce cars with rear-wheel drive, it becomes clear why many motorists are seriously considering buying a car with this type of transmission. Just listen to these names - BMW, Mercedes-Benz, Jaguar, Porsche, Rolls-Royce, Bentley. Hands, as they say, themselves reach out to take a stronger drive of the cars of these companies.
Why such well-known firms Do you prefer rear wheel drive? Of course, they have models with other types of drives in their cohort (front and more often all-wheel drive), but rear-wheel drive cars have become the most popular.
The answer is simple: it's all about comfort and better handling than front-wheel-drive cars. Speaking of rear-wheel drive cars, it is impossible not to mention such sports cars as Nissan Skyline, Toyota Celica, Honda NSX- icons of car racing enthusiasts. That is, we draw an intermediate conclusion, rear-wheel drive is chosen by lovers of comfort or high-speed driving.
Now let's take a quick look at design features rear drive. The design of a rear-wheel drive car can be with any engine layout: front-engine, mid-engine or rear-engine. power unit in such cars it has a longitudinal or opposite arrangement. Torque from the engine is transmitted to the rear axle, which is the leading one.
In addition to various engine configurations, a feature of a car with a rear-wheel drive layout is the presence of a cardan, and, accordingly, a tunnel running along the bottom of the car and interfering with the rear row passengers sitting on the sofa in the middle. However, since most modern cars with rear-wheel drive from the premium class, then they have a 2 + 2 seating formula - that is, there are two full-fledged seats in the back, separated by a tunnel on which a table is placed.
Rear wheel drive advantages:
- the almost complete absence of vibrations from the engine, which in rear-wheel drive vehicles has a longitudinal or opposite arrangement and is suspended on softening elements;
- large loading of the rear axle during acceleration, which allows you to unload the front wheels and provide better grip With pavement rear, driving wheels without slipping;
- more controlled skidding of the car, which occurs at a relatively lower speed than cars with other types of drive, and therefore easier to correct - just let off the gas and turn the steering wheel in the direction of skidding;
- lack of reactive moments on the steering wheel when the car accelerates. This is due to the fact that the front wheels, which are associated with the steering mechanism, are not leading;
- a wide variety of techniques for driving a rear-wheel drive car at speed - which is especially appreciated by racing fans;
reduced compared to front wheel drive car, turning radius, which is explained by the absence of restrictions on the angles of rotation of the front wheels rear wheel drive car hinges of equal angular speeds; - optimal distribution of torque between the front and rear axle: The front wheels turn and the rear wheels "push" the car forward.
Rear wheel drive cons:
- the production cost of a rear-wheel drive car is higher than that of a front-wheel drive car due to the more complex design; - the presence of a massive driveshaft and a tunnel running from the engine to the rear axle hides usable space in the cabin and increases the curb weight of the car;
- worse, compared to front- and all-wheel drive vehicles, cross-country ability loose snow, more prone to skidding on icy roads.
Choice #2 Front wheel drive
Most modern cars have received a front-wheel drive layout, mainly due to the simplicity of this design and lower production costs. In addition, more compact motors began to be installed on cars with front-wheel drive, located not along, like in rear-wheel drive, but across the body.
And the absence of a cardan in the design makes a front-wheel drive car, on the one hand, more compact, and on the other, it allows you to get more voluminous usable space in the cabin and luggage compartment cars.
Since front-wheel drive cars are the most common, more economical and relatively cheap, they are chosen by large quantity buyers.
A little about the design features of such cars. As the name suggests, the main feature of this type drive – transmission of torque from power plant to the front wheels. The front-wheel drive layout allows you to create six variations in the placement of engines - three in the longitudinal and transverse planes. The rear-wheel drive layout has four such variations.
Transversely mounted motors front wheel drive cars can be located in front of the front axle, above it and behind it. The longitudinally mounted engine has exactly the same installation options. In addition, at front wheel drive vehicles it is possible to assemble the power unit in different ways.
In a serial layout behind the motor is located main gear followed by a gearbox. In a parallel arrangement, the motor and gearbox are on parallel axes and at the same height, and finally, in the so-called "floor" arrangement, the engine is above the transmission.
Pros of front wheel drive:
- relative cheapness of production and maintenance;
- the absence of a cardan shaft and rear axle housing allows you to make the car more compact, lighter and more spacious both in the cabin and in the luggage compartment;
- better grip of the front wheels on slippery roads due to the fact that the engine and transmission are located next to each other, and not spaced apart, as in rear-wheel drive cars;
- better dynamics and efficiency of front-wheel drive vehicles due to lower curb weight;
- better compared to rear wheel drive cars, patency on loose snow due to the fact that the front wheels have optimal grip on the road surface due to the mass of the engine located in front of the machine;
- excellent directional stability and a slight degree of understeer, in which a car entering a turn at speed tries to return to a straight-line trajectory itself. This, of course, affects the better safety of a front-wheel drive car.
Cons of front wheel drive:
- due to the location of the engine on the front axle and its rigid “coupling” with the frame, vibrations from the engine are transmitted to the body, which makes the comfort inside the cabin lower than in a rear-wheel drive car;
- reactive moments are transmitted to the steering wheel during acceleration, which complicates its control;
- there is a moment of wheel slip at sharp acceleration car. This happens due to the fact that during acceleration, the weight from the front axle is transferred to the rear, the front wheels lose traction with the road surface;
- a large load on the front tires, which play a major role in accelerating, braking, turning the car. Accordingly, their service life is reduced.
Choice #3 All wheel drive
Perhaps the most desired of all drives for Russians is full. It is great for driving on our less than ideal roads, and is a reliable assistant when overcoming off-road. Currently, the popularity of all-wheel drive vehicles is growing.
Moreover, this applies to machines that use plug-in all-wheel drive systems, which allows such models to have good dynamics and be economical. Most best option- crossovers, in which the base is the drive to front wheel, and if necessary (going off-road), the rear axle is also connected.
It turns out that all-wheel drive vehicles will appeal to those who often travel off-road.
A few words about design features four-wheel drive vehicles. All-wheel drive allows you to transmit torque to both axles at the same time, which ensures optimal grip of the wheels with the road surface. There are three groups of all-wheel drive transmissions: permanent all-wheel drive, all-wheel drive on demand and automatic all-wheel drive.
Permanent four-wheel drive in its design has a center differential with locks, transfer case. The automatically connected all-wheel drive has no center differential in the design, only one axle is leading (most often the rear), and the second one is connected automatically as soon as intelligent system AWD will detect that the drive axle wheels have lost traction.
The all-wheel drive, connected on demand, also has no center differential, the front axle is the leading one, and the rear one is connected through multi-plate clutches.
Advantages of all-wheel drive:
- excellent adhesion of all wheels to the road surface, which ensures the absence of slippage when starting on a slippery surface, as well as high permeability car;
- the most better handling on high speed due to the optimal weight distribution along the axes (typical for all-wheel drive sports cars);
- high reliability of the design (especially for permanent all-wheel drive);
- relative simplicity of design for cars with all-wheel drive (for cars with permanent all-wheel drive, the design is more complex);
Cons of all-wheel drive:
- increased transmission noise;
- uncomfortable driving in the conditions of movement on city streets;
- big weight all-wheel drive transmission, which directly affects the dynamics and efficiency of such a car;
- high cost of maintenance and repair.
So, having weighed all the pros and cons of cars with rear, front and all-wheel drive, each motorist can make his own, reasonable and subjective choice.
