An all-wheel drive system is a transmission design that evenly distributes torque to the rear (single and twin) and front wheels of the vehicle. It is used on cars and trucks (including SUVs) of domestic and foreign production. All-wheel drive allows you to improve the dynamics of acceleration, handling and patency of the car while driving in summer or winter on wet or slippery roads, as well as off-road.
What is permanent and plug-in all-wheel drive
Four-wheel drive is classified into four groups: connected, permanent, automatic, multi-mode. Each type of all-wheel drive has several features.
Pluggable (Part time). This type of drive is used on cars of the brand Kia Sportage (release before 2002), Ssangyong Kyron, Suzuki Jimny, UAZ. Its main task is to reduce fuel consumption when driving on good road surfaces.
Part time is turned on with an additional button or lever. It does not use a center differential. Therefore, in order to avoid accelerated wear of transmission elements and tires, increased fuel consumption, deterioration of handling when cornering, it is recommended not to constantly drive on the Part time drive.
Permanent (Full-time). It is installed on cars of a number of well-known brands: Toyota Land Cruiser, Mercedes ML, Lada Niva, Daihatsu Terios. It has inter-axle and inter-wheel differentials. Ideal for driving on hard pavement.
Automatic (Automatic or On demand). Used on Nissan Quashqai, Mitsubishi Outlander XL, Honda CRV, Chevrolet Captiva. It turns on in automatic mode, if there is a slip of the driving wheels.
Multimode (Selectable). Used in cars of the brand Jeep Grand Cherookee, Mitsubishi Pajero. Has no flaws. It has absorbed the advantages characteristic of other types of all-wheel drive. Allows the driver to drive on two drive axles or only one at his request.
Differences of all-wheel drive from front and rear
Four-wheel drive has a number of differences from the front and rear. Fundamental differences affected the principle of operation, driving on slippery surfaces, and cross-country ability.
Functional differences. In a front-wheel drive vehicle, power is sent to the front wheels only. In a rear-wheel drive car, the engine power is sent to the rear wheels. In an all-wheel drive vehicle, engine power is transmitted to both pairs of wheels.
Differences when operating on slippery surfaces. A front wheel drive car is difficult to skid on slippery surfaces, but even harder to get out of it. For a rear-wheel drive vehicle, skidding when driving on a slippery surface is the norm - to get the car out of this state, it will be enough to release the gas pedal. A four-wheel drive car on slippery surfaces is the most unpredictable - it can behave like a rear- or front-wheel drive car.
Differences when operating on a snowy surface. When the train is on a snowy or muddy road surface, a car with rear-wheel drive will have the worst cross-country ability - the front wheels will have increased slippage, which makes it difficult for the car to move. In a front-wheel drive car, the driving pair of wheels is pressed against the surface of the road surface by the weight of the engine - this factor reduces slippage. As well as the front drive wheels allow the driver to set the direction of traction. The leader in overcoming snowy tracks is a car with all-wheel drive. Such a car overcomes the path with virtually no slippage.
Pros and cons of all-wheel drive
Each type of drive has a number of positive aspects. At the same time, there are also negative sides.
- Permanent four-wheel drive (Full-time);
- Advantages;
- the ability to drive with this drive on a different type of road surface (asphalt, field road);
- design reliability.
- Flaws;
- large drive weight;
- increased fuel consumption;
- complex process of auto controllability adjustment;
- Advantages;
- Plug-in all-wheel drive (Part-time);
- Advantages;
- high cross-country ability;
- reliable mechanics.
- Flaws;
- prohibition of driving with all-wheel drive on asphalt;
- Advantages;
- Automatic four-wheel drive (On demand);
- Advantages;
- light weight;
- simplicity of design.
- Flaws;
- instability characteristics;
- overload resistance;
- low level of reliability.
- Advantages;
In order to drive a four-wheel drive car successfully, you should follow a number of recommendations. For each type of all-wheel drive, the recommendations have several differences.
How to drive a car with multi-mode drive. With multi-mode drive, there are many ways to connect the drive wheels. The choice of these options depends on climatic conditions and the quality of the road surface.
In light off-road conditions, use the automatic mode.. On a slippery road, you need to switch to full-time all-wheel drive. When driving on dry pavement, it is recommended to use one drive axle - this will minimize fuel consumption. In complete off-road conditions, you should use a lower gear, while locking the differential.
How to drive a permanent vehicle. When driving with permanent drive, it is important to use a locking center differential. If you need to overcome a section of the road with a long slippery slope or a thick layer of snow, sand, mud, it is recommended to turn on the differential lock in advance.
How to drive a vehicle with automatic transmission. Driving a car with this type of drive will not be difficult. Four-wheel drive will automatically turn on when overcoming a difficult section of the road (off-road, climbing a slippery road).
How to drive a plug-in car. Four-wheel drive is recommended to be turned on only when driving on off-road or slippery asphalt. If the road surface is hard and dry, you should turn on the drive to one axle.
Related video
Machine drive
Machine drive
a power device that supplies the machine with the energy it needs to run. The drive usually includes a power source, transmission and controls. The source of energy can be a muscular force (of an animal or a person), a mechanical device (for example, a spring or kettlebell mechanism) or (thermal, electric, pneumatic, hydraulic, etc.). Non-traditional sources (solar batteries, wind energy) are also used, which are promising as sources that do not pollute the environment. The drive is built into stationary machines (machine tools, rolling mills and other equipment); installed on moving working machines; used on various vehicles (cars, locomotives, etc.). As a stationary one, it is most often used, in which the source of mechanical energy is an electric motor. On mobile working and transport machines, heat engines with direct mechanical and electrical transmission are mainly used. The leading role belongs internal combustion engines, which are installed on cars, diesel locomotives, ships; gas turbines- on airplanes, gas turbine locomotives; nuclear power plants- on icebreakers, submarines. The electric drive has been widely used in communal household machines (sewing, kitchen, washing), tools (planers, drills). Hydraulic and pneumatic drives are also common (for example, in manual machines), where the energy source is a pressurized liquid or a compressed one supplied by a compressor. Combining an electric drive with a machine made it possible to create automatic machines, and then automatic lines. Machine drive control automation allows for speed control according to a given program, load redistribution, remote switching on and off, precise stop or movement reversal. Automation of the drive increases, increases the productivity of machines as a whole, improves working conditions.
Encyclopedia "Technology". - M.: Rosman. 2006 .
See what "machine drive" is in other dictionaries:
drive unit- A device for driving machines and mechanisms. Note The drive consists of a source of energy, a mechanism for transmitting energy (motion) and control equipment. The source of energy is the engine (thermal, electric, ... ...
A drive is an energy-power device that sets a machine or mechanism in motion. P. usually consists of an energy source, a transmission mechanism, and control equipment. The source of energy is the engine (thermal, electric, pneumatic, ... ... Great Soviet Encyclopedia
Drive: In mechanics Drive (also power drive) is a set of devices designed to drive machines. Consists of engine, transmission and control system. There is a group drive (for several machines) and ... ... Wikipedia
DRIVE, in engineering, a device for driving machines. Consists of engine, power transmission and control system. There are group drives (for several machines or working bodies) and individual drives (for a single machine or for ... ... encyclopedic Dictionary
machine drive- drive A system consisting of an engine and associated devices for driving one or more solid bodies that make up the machine. [Collection of recommended terms. Issue 99. Theory of mechanisms and machines. Academy of Sciences of the USSR. ... ... Technical Translator's Handbook
Drive (device)- DRIVE, a device for driving machines and mechanisms. Consists of power source, transmission, control equipment. There are manual drive (from muscular strength through a mechanical transmission), electric, pneumatic, ... ... Illustrated Encyclopedic Dictionary
A device for driving machines. Consists of engine, power transmission and control system. Distinguish drives group (for several machines) and individual ... Big Encyclopedic Dictionary
Explanatory dictionary of Ozhegov
DRIVE, ah, husband. 1. see lead. 2. Forced delivery to the bodies of inquiry or to the court of a person who did not appear on a call, as well as temporary arrest for interrogation (official). P. to the police. II. DRIVE, a and DRIVE, a, husband. A device or system of devices ... ... Explanatory dictionary of Ozhegov
DRIVE UNIT- a device consisting of an energy source, energy-transmitting (motion) mechanisms and a control system (devices) for setting in motion transport vehicles, various machine tools and millions of their braking mechanisms. Sources of energy (motion) ... ... Great Polytechnic Encyclopedia
Books
- Engineering of transporting machines and devices, S. A. Ivanov. General information about transporting machines and general purpose devices is given. The theoretical foundations for the calculation of continuous transport machines are outlined: productivity, forces ... eBook
- Electric drive. Textbook for academic baccalaureate, R. F. Bekishev, Yu. N. Dementiev. Currently, electromechanical energy conversion is used in almost all technical objects, where the knowledge and work of engineers of many specialties are synthesized. That's why…
Disputes in the driver's community do not subside about whether front-wheel drive car better or rear. Everyone brings their own arguments. But no one in their right mind would deny that without the presence of positive qualities in any device, no manufacturer would produce it at a loss. We just have to figure out all the pros and cons of front-wheel drive in a car.
Front wheel drive.
Let's start with the transmission device front wheel drive car and the history of its appearance. With a front-wheel drive design, the torque from the engine is transmitted to the front wheels. This type of car drive or, in English transcription, FWD (Front Wheel Drive) began to be used massively in cars somewhat later than the rear one. In 1929, it began to be used in the serial production of Carl Van Ranst's "Cord L29". In the 70s and 80s, there was a sharp increase in the production of front-wheel drive cars. Today, their number significantly exceeds the production of rear-wheel drive models. These are mainly mass and not expensive car models. Depending on the type of engine installation, the following vehicle layouts are distinguished with front wheel drive: longitudinal engine installation in front of the axle, longitudinal engine installation behind the axle, longitudinal engine installation above the axle, transverse engine installation in front of the axle, transverse engine installation behind the axle, transverse engine installation above the axle.
Front wheel drive device.
There are three types of layout of the power unit with front wheel drive:
- Sequential arrangement, in which the engine, main gear and gearbox are placed one after the other on the same axis;
- With a parallel layout, the engine and transmission are located on axes parallel to each other at the same level in height;
- The last type is the "floor" layout - the engine is located above the transmission.
Modern technologies make it possible to practically equalize front- and rear-wheel drive cars in terms of consumer qualities, safety and handling, but we will still analyze the advantages and disadvantages of front-wheel drive cars. So, about the benefits:
- front wheel drive cars, as a rule, are more compact, their assembly is less expensive, therefore, they are more economical and cheap;
- due to the fact that the front drive wheels are heavily loaded due to the engine, the patency of a front-wheel drive car is in most cases much better than that of a rear-wheel drive car;
- with insufficient driving experience, front wheel drive car easier to master, especially when parking in winter, as its drive wheels guide the car more precisely to the parking spot;
- the energy generated by the engine is used when turning with greater efficiency, since the front drive wheels turn, and do not move tangentially;
- there is no need to place a cardan tunnel in the cabin, due to the absence of a cardan in the design, and therefore the cabin volume increases.
However, despite the large number of positive aspects, cars with front wheel drive They also have a number of disadvantages, namely:
- they have poor, in comparison with rear-wheel drive, maneuverability in corners due to the limited angle of the constant velocity joints (CV joints);
- due to the simultaneous performance of two functions by the front wheels - traction and turning, the rear wheels simply "drag" behind them, which leads to insufficiently "sharp" handling;
- the engine is rigidly fixed to the car body, and this leads to the transmission of vibrations from the power unit to the body;
- when the car accelerates, a reactive force is transmitted to its steering wheel;
- due to the redistribution at the start of the load back, the front wheels are unloaded, which leads to the car slipping;
- a front wheel drive vehicle is subject to a power limit. When installing an engine more powerful than 200 hp. the load on the undercarriage components increases significantly, which leads to poor machine controllability.
All of the above suggests that before you start managing front wheel drive car, you need to thoroughly study the theory, if possible with an experienced instructor. You need to be especially careful when driving on a slippery road and remember that the way out of a skid on rear-wheel drive and front-wheel drive cars is fundamentally different.
If the task of the motor is to create torque, then the transmission has a role in transmitting it to the drive wheels. Depending on which of them - front or rear - are connected by a transmission to the engine, the car is considered front-wheel drive or rear-wheel drive. In this article, you will learn how rear-wheel drive differs from front-wheel drive and what are the advantages and disadvantages of both of these schemes.
The first cars were produced according to the rear-wheel drive scheme. This is due to the simpler arrangement of the engine, gearbox, rear axle gearbox along the longitudinal line of the car body. The flexibility of the connection is provided by the cardan shaft.
The rear axle, in the casing of which there are two axle shafts with wheels, is located at a right angle to the axis of the cardan. For such an arrangement, a full-size gearbox had to be created. The complexity of its device lies in the independence of the two rear wheels: when turning, the inner one moves faster than the outer one.
It is quite simple to see the operation of the gearbox: it is enough to raise one of the rear wheels with a jack, start the engine and engage the gear (putting shoes under the front wheels). A wheel standing on the pavement will be motionless, and a wheel hanging in the air will begin to spin. This is the work of the differential, which distributes torque between the axle shafts of the rear axle.
Front-wheel drive: device and reasons for popularity
The principle of transferring the rotation of the motor, the gearbox shaft to the wheels is similar to the rear-wheel drive: a gearbox with a differential and cardan shafts are required. The difference lies in the constructive solution of these components and assemblies.
The front wheels, being the leading ones, required a closer placement of the checkpoint to themselves. This made it possible to locate the engine-gearbox linkage on the same center line with the wheels in the front engine compartment. The transverse placement of the motor forced the engineers to create a more compact engine and gearbox while maintaining their power. Therefore, despite the appearance of the first prototype of a front-wheel drive car at the beginning of the 20th century, they began to be mass-produced only in the second half of the last century.
If the gearbox, the gearbox of such an arrangement are structurally similar to the rear-wheel drive, then the universal joints have a significant difference. The front-wheel drive scheme involves CV joints, or ball-bearing angular velocity gearboxes. If the universal joint has two degrees of freedom, then the CV joints connect the two axle shafts more smoothly. The angle of such a joint reaches 70 ° without serious, unlike the cardan, wear of rubbing parts. Also, CV joints allow you to change the angle of rotation of the wheels - to drive a car.
Comparison of two types of drive: their advantages and disadvantages
Despite the differences in layout details, the front-wheel drive was created with the motor placed in the area of the front wheels. The rear-wheel drive scheme is more flexible in this regard and allows the motor to be located anywhere. There is a front-engine, mid-engine (in front of the drive wheels) and rear-engine layout. To understand how rear-wheel drive differs from front-wheel drive in practice, it is necessary to compare their strengths and weaknesses.
Pros of rear wheel drive
- Rear-wheel drive allows you to achieve high maneuverability of the machine due to less restriction on the angles of rotation of the front wheels.
- Good stability on the ground: the leading pair works on the track already laid by the front pair.
- An elongated ligament (motor, steered front wheels and driven rear wheels) allows you to more gently control the machine during skidding - uncontrolled drift from the canvas of the leading pair.
- When starting from a standstill, the mass of the body is transferred to the rear, increasing the grip of the tires on the road.
Flaws
- Rear wheel drive is more prone to skidding.
- Such a scheme requires a larger working volume, not allowing to minimize the body.
Front wheel drive problems
- The concentrated mass in the front of the engine compartment (engine, gearbox, gearbox, axle shafts, CV joints) eliminates proportional weight distribution on the body.
- Acceleration from a standstill often occurs with slippage due to the transfer of body weight to the rear.
- When skidding, the car on the road is more difficult to keep due to the combination of control and drive functions in the front wheels.
Advantages
- This layout makes the car more passable on wet ground: it pulls the car like in tow, and does not push all the weight in front of it, as with rear-wheel drive.
- Front-wheel drive gives the car less weight, compact placement of units, which makes it easy to modify the body in two and even one-volume layout options.
- The inseparable combination of machine control both in speed and in direction allows you to better “feel” the steering wheel.
Modern technology compensates for many of the difficulties of front and rear wheel drive, so the choice often comes down to the personal taste of the user, not the capabilities of the machine.
Video about rear and front wheel drive
When choosing a car came across a question drive. Tell us about the types of drives existing in the car. Thank you.
(Igor Kondratiev)
It is known that the engine compresses and burns fuel, converting it into mechanical energy. This energy forms a torque and transfers it to the wheels. The drive is called the axle of the wheels to which rotational movements are transmitted. It can be front, rear and full.
Each type of transmission has its own characteristics, as well as advantages and disadvantages.
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Front
On front-wheel drive vehicles, the engine, generating energy, transfers it to the front axle or, more simply, to the front wheels. This design is most often used on budget-class cars, however, it is also found on more expensive cars. It is noteworthy that such an arrangement is quite simple and practical.
Learning to drive a front-wheel drive car is much easier. Therefore, such cars are preferred for beginners. Of the disadvantages: it has lower dynamic performance and an increased likelihood of front wheel drift. The advantage is high cross-country ability on slippery roads and a lower degree of skidding, unlike rear-wheel drive cars.
Rear
Obviously, in such a design, the rotational energy is transferred to the rear pair. It is found on expensive cars, especially European and American production. In terms of dynamics and speed indicators, such cars take their advantage. Due to this, it has good maneuverability and controllability. That's just the tendency to drift in cars with front-wheel drive is higher. This is due to the fact that the front wheels are the braking factor at the time of the turn, and the rear wheels are the excess pushing force.
Full
A car in which torque is distributed to all axles is all-wheel drive. Perhaps the most common of all existing types. Cars of almost all classes and body types have this arrangement. In addition to high cross-country ability and versatility, this design has earned its popularity with the so-called “plug-in” drive system.
This solution allows the car to use the leading one axle of the wheels and, depending on the situation and road conditions, connect an additional second one.
It turns out that the full type has three groups of transmissions:
- full, using the front and rear axles at the same time;
- plug-in full on demand, where the front axle of the wheels is the leading one, and the rear one is plug-in;
- automatically connected - the rear pair is usually the leader, and the front pair is turned on automatically as soon as the drive wheels lose traction.
All modern cars, regardless of the type of drive, are most often equipped with an ESP stabilization system. Thanks to this system, your car will behave on the road as comfortably and calmly as possible.
Video "Types of drives"
Learn more about the types by watching this video:
