Every driver faces a choice of which car model to give preference to. Everyone wants to have a powerful and reliable SUV who would overcome any difficulties. Each car has a number technical characteristics, And important aspect When choosing an SUV or crossover, it is necessary to have all-wheel drive or plug-in drive. Many will agree that all-wheel drive is much more convenient and better.
In this article we will try to understand all the positive and negative aspects full permanent drive at crossovers.
Plug-in or permanent?
Many will say that there is not much difference between all-wheel drive and all-wheel drive, as this technology will work just as reliably in both situations. But experienced drivers surely they know how the difference exists. It's all about fuel, because when permanent job All-wheel drive fuel consumption increases noticeably. Owners of older cars probably know this. Even modern ones passable cars with a power distribution system they still consume more fuel than SUVs with plug-in or just front-wheel drive.
Fuel consumption also depends on the driver’s driving style. If you drive the car slowly and evenly, then fuel consumption will not exceed the norm.
As practice shows, even cars sometimes they consume more fuel than large SUVs with permanent all-wheel drive. If you are a careful driver, then you don't have to be afraid huge expense, since most of the responsibility lies on the shoulders of the car owner.
The increased consumption is due to the fact that the car drives along a curve or on severe off-road conditions. When driving like this, differentials are connected, which take away excess power. And if the car moves on a flat and straight road, then the car consumes no more than the average. Currently, there are not many enthusiasts of off-road or off-road driving. Many drivers prefer to drive in urban environments and rarely even go outside the city, so they choose SUVs with all-wheel drive. And the lovers steep slopes and quarries do not even think about what type of drive they should choose.
In winter, permanent all-wheel drive still becomes the leader, since drivers do not always have time to connect four-wheel drive on an icy road, so accidents often occur. With constant drive, the driver can feel confident even on a skating rink. But it’s worth considering that such SUVs are much more expensive than cars with plug-in or only front-wheel drive.
Don't give in to temptation and buy inexpensive crossovers with so-called all-wheel drive or all-wheel drive, since they still do not reach the level of reliable SUVs. This is because they are not equipped with a frame structure, underrun bars, or low gears. Without these functions, no car can cope with severe off-road conditions.
On the one hand, permanent drive has a number of advantages, since the driver does not have to constantly engage all-wheel drive. Off-road with a reliable car, everyone will feel at their best, but at the same time, such cars cost a lot, plus, because high flow rate fuel becomes contaminated environment.
We should talk about representatives of cars with permanent all-wheel drive. And the first on our list will be Acura MDX- a five-door SUV that seats up to five people. Manufacturers approached the technical equipment with responsibility, which is why the SUV has a short wheelbase, independent suspension, impressive ground clearance, as well as a six-cylinder three-liter engine whose power is about 290 Horse power and automatic six-speed transmission. In just 7.5 seconds all-wheel drive SUV accelerates to 100 kilometers per hour.
Another version of the Acura MDX SUV is equipped with a six-cylinder engine with a displacement of 3.7 liters. We can say that this car has the same qualities as the previous car in this model range. The maximum speed of the car reaches about 190 kilometers per hour.
Acura RDX
The next SUV is a representative of the same car company. Acura RDX - five door car, which accommodates up to five people. In length large SUV reaches 4.6 meters, and the width of the car is 1.8 meters. If speak about technical equipment, then it's pretty good. It should be noted that the six-cylinder engine produces 270 horsepower. With such an engine, the SUV accelerates to one hundred kilometers per hour in almost 8 seconds. Of course, it's not as fast as previous models.
Another representative of the Acura automobile company is an all-wheel drive gasoline SUV, whose name is Acura SLX. It also has permanent all-wheel drive and seats up to five people. The main advantage of this SUV is its six-cylinder engine, whose power is about 190 horsepower. A three-liter is capable of accelerating a car in 10 seconds to one hundred kilometers per hour. A maximum speed, which this model can achieve is 166 kilometers per hour. Also worth noting is the five-speed manual transmission and reliable suspension Acura SLX car.
The next SUV of the same model range is equipped with a 3.5-liter engine. In all respects, this model is similar to the previous one, however, there are some differences.
For example, power has increased. The engine currently produces 215 horsepower, which is much more than previous model. Yes, and the automatic four-speed transmission is different from the Acura SLX 3.2 version. It is also worth noting that the Acura SLX 3.5 accelerates to 100 kilometers per hour in 9 seconds.
Acura ZDX is a four-door car with a 3.7-liter engine. The SUV can also accommodate up to 5 people in the cabin. The car has impressive dimensions. It reaches almost five meters in length, and the width of the SUV is 1.9 meters. The Acura ZDX is equipped with an impressive ground clearance, a short wheelbase, and a six-cylinder engine producing 300 horsepower. This is so far the fastest SUV that we talked about on this moment. The all-wheel drive vehicle is equipped with an automatic transmission and independent front and rear suspension. It is worth noting that the car can accelerate to 205 kilometers per hour.
We finished looking at SUVs from the Acura car company and moved on to Alpina car The XD 3 Biturbo is a six-seater SUV equipped with a six-cylinder three-liter engine with a power of 350 horsepower. It is worth noting automatic transmission transmission All-wheel drive and independent front and rear rear suspension. Note that the Alpina XD 3 Biturbo SUV justifies the Biturbo prefix, as it is capable of accelerating to 255 kilometers per hour.
ARO 10
ARO 10 - three door compact crossover with connected all-wheel drive. The car has impressive ground clearance, four-cylinder engine, the volume of which is 1.4, which is a rather modest result. And the power is not so stunning, since it is equal to 58 horsepower. It is worth noting the manual transmission with all-wheel drive.
The ARO 10 with a 1.4-liter engine has absolutely the same data. But still, this model is slightly more powerful than the previous one; the SUV’s power is 62 horsepower.
And the third representative of the ARO 10 model range is an SUV with a 1.6-liter engine and its power is 72 horsepower. The car also seats up to five people and is equipped with a four-cylinder engine and manual transmission.
At first glance, the operating principle of an all-wheel drive vehicle's transmission is simple: torque from power unit distributed between four drive wheels. Such a machine is very convenient due to its pronounced advantages associated with the unpretentiousness to the quality of the coating under the wheels. On a dirt road, in icy conditions, on wet countryside or on a highway in heavy rain four wheel drive vehicle will show itself at its best. Plus, on it you can not be afraid to drive off the asphalt surface and cross terrain without even a hint of roads, and even on asphalt, all-wheel drive makes itself felt with good start and acceleration, with virtually no slipping.
But sometimes incidents happen that seem difficult to explain due to the advantages that all-wheel drive vehicles have. It happens that a driver is sitting behind the wheel of an SUV with impressive ground clearance, and the car is stuck in a “porridge” and lies on its belly.
Interesting to know! In 1883 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 put it, is “the gasket between the steering wheel and the seat.” But it also happens that the all-terrain vehicle’s transmission is not designed to cope with the assigned tests. And then reasonable questions arise: “Why can’t it cope?”, “Which one can cope?” We will talk about this further in the material provided.
Manually engaged all-wheel drive (Part-Time)
This type transmission can rightfully be called the “first-born” among all-wheel drives. The principle of its operation is to rigidly connect the front axle. Thus, all wheels rotate at the same speed, and there is no center differential. Torque is distributed equally between all wheels. In this case, it won’t be possible to do anything to make the axles rotate at different speeds, except perhaps penetrate into the “belly” of the car and install a new differential.
In the meantime, it is not recommended to cut through traffic with the front axle connected. If you move straight even in a low gear for short distances, nothing bad will happen, but if you need to turn around, then the resulting difference in the length of the bridge paths 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 on surfaces is weak. But if the weather is dry and you are moving on an asphalt road, then there will be nowhere to get power except off-road. Thus, the transmission is subjected to increased loads
, the tires wear out faster, handling deteriorates and directional stability is lost at high speeds. If the car is used more often off-road or is generally purchased only for off-road driving, then the all-wheel drive system with forced connection front axle will fully meet your expectations. The bridge is connected immediately and firmly, so there is no need to block anything. The design is very simple and reliable, there are no locks or differentials, there are no electric or
mechanical type , there is no unnecessary hydraulics and pneumatics. But if you are an urban “dandy”, you value time and don’t want to worry about weather conditions and alternating sections of the city with its loose and slippery road surfaces, treacherous deep puddles, then a variant of this
all-wheel drive system It doesn't suit you at all. If you move 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 you may not have time to connect it at all., 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
The disadvantages of plug-in all-wheel drive became the root cause for 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 “what if”: all the wheels are driven, there is a free differential between the axles, which releases the accumulated excess power by turning 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 starts to slip on one axle, the second one is automatically switched off. Now the car has turned into furniture or a house, as you wish, in general, into real estate. How does this happen? If one wheel starts to slip, the inter-axle differential disables the second one, and the second axle is also automatically disengaged by the differential, but this time by 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, inertial force. The wheel turns off, moves forward by inertia for a couple of meters and turns on again. But in this case, the car will sooner or later stall somewhere. So to save everything off-road qualities “rogue”, such cars are usually equipped with one or two forced blocking center differential. IN front differential
It is very rare to see a factory lock. If desired, it can be installed separately. But the permanent all-wheel drive system is also far from ideal driving performance on paved roads. Such cars handle, let's just say, I wish they were better. IN critical situations The SUV pulls to the outside of the turn and it does not immediately respond to steering and accelerating.
Drivers of such cars require special skills and an excellent feel for the vehicle.
If one of the axles begins to slip, the self-locking mechanism is activated, and the differential does not affect the second axle, which continues to receive torque. A number of cars were also equipped with a self-locking mechanism for the rear axle differential, which had a positive effect on the sharpness of control.
Among cars with permanent all-wheel drive, we can distinguish Toyota Land Cruiser 100, 105, Land Cruiser Prado, Land Rover Discovery, Land Rover Defender, Lada 4x4.
Automatically connected Torque on-demand 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 redistribution and transfer of torque. As a result, stabilization systems appeared and directional stability, traction control systems, as well as systems that distribute torque. All of them are implemented using the electronics involved. How more expensive cost car and its more modern filling, especially complex circuits are applied to her.
This includes monitoring the steering angle, body roll and speed, right down to how often the wheels oscillate over a certain period of travel. The car collects the most complete information about its behavior while driving. The ECU processes it and regulates the transmission of torque between the axles through an electronically controlled clutch, which replaces 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. Manufacturers only need to add a few new sensors and parameters, thanks to which the system works ahead.
But here there are some nuances of use: this type all-wheel drive transmission Suitable for use only on asphalt roads with rare inclusions of symbolic off-road conditions, primers, for example. Mostly, electronic couplings When slipping off-road, they begin to overheat and fail. And for this you don’t need to plow tank ruts for hours; ten minutes of skidding on ice is enough. But if you overheat it systematically, then breakdowns cannot be avoided, as well as expensive repairs.
The “cooler” the system, the more susceptible it is to breakdowns. So you need to choose a car wisely, having determined for yourself which routes you will drive it on. Don’t go to extremes: if it’s an SUV, then only in the forest and in the countryside, and if it’s 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. In a passenger car, of course, you can drive onto a country road, but which one and which one is another question.
If on one of ABS sensors If the wiring breaks, the entire system will immediately fail and will not receive information from the outside. Or the gasoline wasn't poured in best quality– and that’s it, the downshift won’t engage, a trip to a car service is ahead. Or it may happen that the electronics will put the car into service mode, completely turning off all its vital systems.
Among these cars 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.
Multi-mode (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 axle s. Using the Selectable 4wd system does not improve fuel consumption. The leaders in fuel overconsumption are the part-time cars we mentioned at the beginning.
Some cars stand apart with a selective transmission, which can be called permanent all-wheel drive, with the ability to forcibly disable the front axle. On such vehicles, the transmission combines part-time and full-time. Among them Mitsubishi Pajero, Nissan Pathfinder, Jeep Grand Cherookee.
In the Padzherik, for example, you can choose one of several transmission modes: 2WD, 4WD with automatic locking center differential, 4WD with hard differential lock or downshift. As you can see, here you can find references to all of the above all-wheel drive systems.
Some front-wheel drive cars may have a driven rear axle. Into the body final drive a small electric motor is mounted, which can be connected at the driver’s request - the e-4WD system. The electric motor is powered by car generator. This system improves the car’s handling on the highway in a downpour, and also helps you navigate snowy, icy and muddy sections of the road with confidence. Prominent representatives cars with this system are the latest BMW models.
Before you start looking at the differences in all-wheel drive systems, you need to define what all-wheel drive is in general. So, this is the transmission design of a four-wheeled vehicle to transmit power (torque), engine generated, on all wheels. All-wheel drive is usually abbreviated as AWD or 4WD. Essentially this means the same thing, but generally speaking, 4WD means all-wheel drive, manually switched off and on, and AWD means permanent or automatically engaged all-wheel drive.
Based on their purpose, all four-wheel drive systems can be divided into three large categories. Let's consider each of them separately.
Part Time “partial time” - manually activated all-wheel drive system
This system means that if you are driving on a paved road, only the rear axle (rear wheel drive) must be engaged, and all-wheel drive is only allowed to be engaged briefly, for example, on a wet or slippery surface. Otherwise, you will not avoid damage to the transmission. All this is due to the design of the manually connected all-wheel drive system, in which there is no center differential.
It is worth noting that today, due to its inefficiency, this type of all-wheel drive is almost never used. But, at the same time, it is this system that is capable of providing a rigid connection between the front and rear axle. Off-road, such all-wheel drive vehicles work just fine, and they cost much less. However, if you don't really intend to go off-road, then buying a car with the Part Time all-wheel drive system will be a waste of money for you, since in reality you will only get a gas-guzzling, large rear-wheel drive station wagon.
As an example of cars that use a manually connected all-wheel drive system:
- Nissan Navara
- Nissan Xterra
- Opel Frontera
- Ssangyong Musso
Conclusion: The Part Time system is good for off-road use, but absolutely useless when driving on the highway.
On Demand “on demand” - an all-wheel drive system that is automatically connected
In another way, this type of drive can be called automated Part Time. The system ensures that the wheels of one of the axles are connected in the event that the wheels of the other axle begin to slip. For example, if the car is driving in mode rear wheel drive and at some moment the rear wheels begin to slip, then in this case the front axle is automatically connected and part of the torque is already transmitted to it, and the amount of transmitted torque can vary within certain limits.
On Demand can be called another low-cost way for the manufacturer, which fully allows him to call his car all-wheel drive. However, in this case, it should be taken into account that if you drive such a car only on asphalt, without going off-road, then under normal operating conditions your four-wheeled friend is only rear- or front-wheel drive, which also has worse braking qualities , safety level, handling characteristics and higher fuel consumption. However, such systems are good when driving on snowy surfaces.
Almost all leading automakers have in their model range vehicles with automatically connected all-wheel drive, here are some of them:
- Chevrolet Captiva
- Infinity FX35
- Honda CRV
- Hyundai Tucson
Conclusion: The On Demond system is very useful when driving in snow, but otherwise not as good as it should be.
Full Time “full time” - permanent all-wheel drive system
The point of this type of all-wheel drive system is that in this case the all-wheel drive can be kept on all the time. Distinctive feature The design of the permanent all-wheel drive system is the presence of a center differential.
But, one way or another, the Full Time system is divided into two categories:
1. A system where there is no center differential lock or urban Full Time, in which the design of the connection between the rear and front wheels allows them to slip relative to each other. This type of permanent all-wheel drive is more suitable for driving around the city, so if you do not expect frequent off-road driving, then this should not worry you. Vehicles with this drive include:
- Daihatsu Terios
- Ford Explorer
- Lexus RX35
- Hyundai Santa Fe
- Audi Q7
2. A system where the center differential lock is present or Full Time off-road and on-road. This means that these vehicles are truly designed to operate in full-time drive mode, both off-road and on asphalt. These cars include:
- Toyota Prado
- Suzuki Grand Vitara
- Land Rover
- Jeep Cherokee
Conclusion: The Full Time system is good both on the highway and off-road, but such a car also costs much more.
Off-road vehicles have various designs all-wheel drive systems. Each of them has its own advantages and disadvantages. We will talk about the plug-in all-wheel drive system, or as it is also called part-time. What are its “trump cards” and main “cons”?
Part-Time all-wheel drive system
main feature drivepart -time is that when moving along ordinary roads with hard surfaces, only one axis is involved. In essence, in this mode the car remains single-wheel drive. The second axle can be connected if necessary, in case of need to overcome off-road conditions.
To connect the second axis use transfer case. As a result, when such a transmission operates in all-wheel drive mode, there is a rigid connection between the front and rear wheels, as well as the distribution of torque between them in a ratio of 50:50. This is the diagram classic SUVs. And it should be noted that this type of transmission turns out to be very effective when it is necessary to overcome difficult off-road conditions.
But there is drivepart -time and a significant minus. A rigid connection between axles can only be used on surfaces that allow one of them to slip. These are gravel, ice, sand, mud, etc.
The fact is that when bridges are tightly connected to each other, a phenomenon called power circulation occurs. Moreover, if the car is moving on a hard asphalt surface, it can have very large values. This circulating power does not take part in overcoming the forces that impede the movement of the car, thereby further loading the transmission components and tires.
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As a result, the part-time all-wheel drive system is suitable either for driving on asphalt roads, or for outright off-road use. It is completely unsuitable for driving on roads with changing surface properties (asphalt with spots of ice, hard primer with puddles of mud, etc.).
Therefore, today the part-time drive has practically become obsolete and is not used in the automotive industry. It can only be found on old freight trucks. all-wheel drive cars or classic all-terrain vehicles.
Part-Time Drive
Off-road vehicles are in quite high demand among drivers. Not all of them are SUVs, but almost any all-wheel drive system (AWD or 4WD) will allow the owner to special problems go on a country picnic or to the country house.
There are many types of systems; almost every automaker gives them their own names:
- xDrive BMW all-wheel drive system;
- Quattro - Audi;
- 4motion – Volkswagen;
- TOD (ATT) Ssang Yong and Hyundai;
- Super Select(Easy Select) – Mitsubishi;
- Active Select – Chevrolet and others.
Meanwhile, they are all divided into two main categories: full-time and part-time AWD. The first group includes systems in which all-wheel drive is constantly engaged, dividing the torque between the axles in equal proportions. Full-time all-wheel drive is available in classic all-terrain vehicles such as the Land Rover Defender, the domestic Niva and Chevrolet Niva, as well as passenger cars such as the Audi A6 Quattro, BMW X5 and many others, but the AWD transmission design of passenger cars is completely different from cars designed for off-road use.
SUVs, having permanent all-wheel drive, are able to overcome difficult terrain quite easily, and passenger cars permanent all-wheel drive is needed for better dynamics and controllability, because The slipping of the drive wheels is significantly reduced. True, both have to pay high flow rate fuel consumption when driving on paved roads; in addition, the design of a permanent all-wheel drive system is much more complicated.
The second group of all-wheel drive systems is part-time. A machine equipped with such a system is, under normal conditions, single-wheel drive, and the second axle is connected, if necessary, manually or automatically under certain conditions.
Typical part-time four-wheel drive vehicles:
- all UAZ models;
- Mitsubishi Pajero with Super system Select;
- Nissan Patrol.
These machines are perfect for active rest in off-road conditions. The driver in them independently connects the second axle to overcome difficult places.
The part-time AWD scheme has its drawbacks. One of the main ones is that an inexperienced driver cannot always correctly assess the road situation and switch the car’s transmission to all-wheel drive mode in time. The second disadvantage is that with all-wheel drive engaged, you can only move at low speeds, and the transmission wears out a lot. The third disadvantage is that the classic manual part-time system does not have a center differential, which greatly impairs the handling of such cars on dry roads, especially noticeable when cornering.
Crossovers, as well as station wagons with cross-country ability. They are not intended for driving on winter and summer roads, but the capabilities of these cars are quite sufficient to not be limited to driving only on asphalt roads. AWD is implemented in them using a viscous coupling, a Torsen self-locking differential, or a multi-plate friction clutch.
4 motion
One of the most famous automatic AWD transmissions is 4motion from Volkswagen. It consists of the following nodes:
- clutch;
- gearboxes;
- main gears of the front and rear axles;
- cross-axle differentials of the front and rear axles;
- Haldex multi-plate friction clutch;
- axle shafts
Under normal conditions, 90% of the torque is transmitted to the front axle. When the front wheels slip, the control unit sends a corresponding signal, the clutch is blocked, and torque is supplied to the rear axle. Its value is not constant. Torque ratio between front and rear axles in the AWD transmission, 4motion can vary from 90:10 to 60:40.
TOD all-wheel drive system
The Torque-on-Demand AWD transmission, or TOD, belongs to the full-time AWD category, using a variable torque distribution between the axles. The rear axle in the TOD system is permanently connected, the front axle is connected through a multi-plate friction clutch automatically or forcibly using a switch.
IN automatic mode, which is the main one for TOD, torque is redistributed between the axles (front and rear) in ratios from 0:100 to 50:50, it all depends on various road conditions. Before overcoming difficult areas, the manufacturer recommends forcibly connecting the front axle, thereby dividing the torque equally between the axles.
Structured in a similar way intelligent system xDrive BMW cars, however, it operates fully automatically, and the torque ratio between the axles ranges from 0:100 to 40:60.
Quattro all-wheel drive system
Quattro AWD system used on Audi cars, also falls into the full-time AWD category. The role of the center differential in the latest, fourth generation of the Quattro transmission is performed by a self-locking asymmetric differential with ring gears. Under normal conditions, it sends 40% of the power to the front axle, and the remaining 60 to the rear. When wheels slip, the bulk of the torque is transferred to the axle that has the best traction. In this case, up to 70% can be transferred to the front wheels, and up to 85% to the rear wheels.
What should you choose?
The question of which all-wheel drive system is better plagues many car enthusiasts. Many will be surprised, but it is impossible to answer it due to the incorrectness of the wording itself. You can say which is better in a particular situation, but not in general.
After all Mitsubishi car Pajero with the Super Select part-time all-wheel drive system, while being an excellent SUV, on a paved road shows very mediocre handling, which is characteristic of almost all “jeeps”. As well as Audi Allroad with the Quattro AWD transmission, which behaves perfectly on the highway and is capable of driving on compacted dirt roads, will be completely powerless in the conditions of Karelia.
When choosing, it is necessary to take into account the differences in all-wheel drive systems and understand why the car is being purchased, in which case the buyer will receive exactly what he needs - either a spacious family car, in which you can go to the sea, even to the country, or an SUV capable of conquering the Siberian taiga.
