All-wheel drive Niva (VAZ-2121) and its features

Any VAZ car is different from the Niva. And not only VAZ, but any other. The fact is that Niva has a constant four-wheel drive... This required the introduction of a transfer case into the transmission (the connection between the wheels and the engine). Because of this difference, there is a lot of confusion and many questions. Here are the answers to some of them.

1. No car without differential... What it is? it mechanical device, which distributes the tractive effort from the engine to two wheels and provides them with the ability to rotate at different speeds. The differential is vital for the car - when cornering inner wheel the path travels less, and the outer travels more. If there was no differential, then there would be heavy wear of the rubber or when cornering, one wheel would skid, rotating faster, the other would brake, rotating slower. All this would provoke a skid. And the axle loads would be very high.

In the drive transmission of the Niva such differentials three... one in each axle (interwheel), so that the wheels have different speeds of rotation and one more, center. located in the razdatka, to distribute traction between the axles. This differential allows the wheels of different axles to move at different speeds. In a normal straight-line motion without slipping, the traction force is halved by all differentials, and the same torque is supplied to all wheels. When the wheel slips through the differential, all the torque will go to the skid wheel, and the traction force of the other wheels will decrease.

2. One of the main misconceptions regarding the Niva drive, it is a myth about the possibility of connecting the front drive with the front handle "transfer case"... The fact is that the front end of the Niva is always on, it is a car with a permanent all-wheel drive. And the mentioned handle changes the work of the transfer case differential. When the handle is in the forward position, the differential works, in the reverse position it is locked. Why is this necessary? When the lock is disabled, the traction force is equally distributed between the axles, but if the center differential is blocked, then the traction force is distributed in a completely different way. In this case, the tractive effort is transferred towards greater resistance. If, for example, the rear wheel slips, then all the moment is spent on the slipping wheel. But if you turn on the inter-axle lock, then the torque will begin to flow to the front axle, and the Niva will be able to overcome the obstacle. If at the same time the front wheel also stalls, then the Niva will definitely not be able to leave. True, if you put an interwheel differential lock, and there are also such automatic locking differentials, then the Niva will be able to leave on one wheel.

3. Another misconception associated with the Niva drive: when shifting the rear handle (large) we increase the engine power... This is not true. This handle can be changed for transmission ratio between the wheels and the engine and change the tractive effort on the wheels. In the transfer case, in addition to the differential, there is a reduction gearbox, which is like a two-stage gearbox. The work of this gearbox is controlled by this handle. When engaging a low gear, we shift the gearbox operation towards the transmission of increased tractive effort. the speed of movement is significantly reduced.

Therefore, before off-roading, it is best to engage a lower gear, which will increase traction. It is best to turn it on and off when the vehicle is stationary.

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The Niva car became the first Soviet SUV to use an all-wheel drive transmission. A characteristic feature of the car is the center differential locking mechanism. There is an opinion among motorists that this mechanism serves to connect front axle... But, front-wheel drive Niva is always connected. You can figure out what kind of drive the Niva has after studying the design of this unit.

Niva drive device

The chassis of the car is made on the principle of permanent all-wheel drive - from power unit transmitted to all 4 wheels. This scheme improves the performance of the car when driving off-road, while reducing the load on the transmission parts.

The drive for the Chevrolet Niva consists of the following units:

1. Gearbox.
2. Transfer case.
3. A pair of driving and cardan shafts.
4. Front and rear axle reducers.

The transfer case is designed to distribute the torque between the drive axles vehicle... The car is equipped with a two-speed "transfer case", which provides:

• stable movement of the machine when driving at low speed in mode increased speed engine;
• distribution of power between the driving axles, depending on the adhesion to the road surface.

Differential is one of essential elements transmissions. Its main purpose is to distribute the tractive effort, and, if necessary, to ensure the rotation of two consumers with different angular speeds. In transmission drive Chevrolet Niva has three differentials:

1. One for each axle (interwheel) - enable the wheels of one axle to rotate at different speeds.
2. The third (interaxle action) - transfers power from the power unit to both axles of the vehicle. It also allows the shafts to operate at different angular speeds, depending on the operating conditions, which significantly improves handling.

A pair of cardan shafts (CV joint or cross design) provide the connection of the transfer case with the drive axle gearboxes. Both shafts of the car have the same device - they are interchangeable.

Front and rear axlewe transfer the force from the transfer case to the drive wheels through the outer and inner rotary speed joints.

The principle of operation of all-wheel drive on the Chevrolet Niva

In normal mode, the Chevrolet Niva works in high gear with an unlocked differential. The torque is transmitted from the power unit, through the gearbox and intermediate shaft, on a two-stage transfer case gearbox. The center differential is installed in the “hand-out” housing. It links the front and rear axles, allowing them to rotate at different speeds depending on road conditions and direction of travel.

How does four-wheel drive work on a Niva with a locked differential

With all-wheel drive engaged, both propeller shafts are locked by a locking clutch. This contributes to an even transmission of traction to both axles of the vehicle. Due to this, the cross-country ability of the car increases, but the handling deteriorates.

Tip: It is not recommended to use the blocking mode on roads with good grip, as this will lead to accelerated tire wear, an increase in the load on parts and transmission units, and also increase fuel consumption.

How to turn on four-wheel drive

Since the drive on the Niva is constantly full, the question of how to turn on the all-wheel drive on the Chevrolet Niva means how to enable the center differential lock.

You need to use blocking in the following cases:

• when driving on difficult terrain where there is a danger of wheel slip;
• when there is a lack of engine thrust;
• when driving on a road covered with snow or ice.

Important: The blocking is useless when the vehicle is suspended diagonally, when one wheel on different axles starts to slip. It's connected with design feature transmissions. In this case, you need to act according to the situation - undermine or pour under the suspended wheels.

The main component of the axle locking mechanism is the transfer case. Control transfer case carried out by one six-position lever. Longitudinal travel provides high and low gear rows. Transverse - is responsible for blocking the center differential. When the lever is in lock mode, the icon on the instrument panel lights up yellow color... There are no synchronizers in the design of the transfer case, therefore, when you try to turn on the speed range or blocking, the gears stand tooth to tooth. To switch, you just need to move the car forward or backward and then everything will switch.

The VAZ 2121 car, in other words, "Niva" - entered mass production in the 70s of the last century. Such a car belongs to the class passenger cars high cross-country ability... In history domestic auto industry "Niva" became the first car in the design of which four-wheel drive was used. Let's take a closer look at the transmission device. This should be done in order to understand why, given the almost 40-year history of the Niva transmission, it differs from many other similar machines equipped with all-wheel drive and the ability to switch in the classical way or using a viscous coupling.

The transmission in the Niva family (2121, 2131) is designed in such a way that four-wheel drive is supplied. The presence of an interaxle differential is also characteristic. The transmission includes a gearbox, a transfer case, a pair of propeller shafts, and both axles. The 2131 features a long body. Otherwise, the predominant similarities with the first model can be traced throughout. From the motor there is a transfer of torque through the gearbox to the "razdatka", and she, in turn, transmits the moment to the bridges.

Further through cardan shafts he goes to the gearboxes. The front gearbox transmits torque to the wheels through a differential and constant velocity joints. Likewise for the rear, also protruding leading, wheels. Precisely because the torque is distributed to 4 wheels at the same time, the drive is called complete. The designation is as follows - 4WD. Another one domestic car, arranged on a similar principle to "Niva" - UAZ.

Such a mechanism is a kind of distributor of traction forces coming from the motor to the wheels. An important feature is that the latter have the ability to rotate at different speeds. The importance of the presence of a differential mechanism is due to the fact that during the turning maneuvers, the wheel inside makes the number of revolutions less, if we compare them with the number of turns on the outside.

In the absence of a differential mechanism, this would cause disastrous consequences, such as wear and damage, because the following would turn out: one wheel would be in the axle box when cornering, and the other would simply rub against the road surface. The design features of the Niva transmission provide for the presence of 3 differentials. They are located in each of the axles and in the dispensing mechanism.

When the machine is moving on a flat road and in a straight line with differentials, the traction effort is divided equally between all 4 wheels. In case of insufficient adhesion of the wheels to the coating, the appearance of slipping, the differentials will redistribute the load on the skidding and sliding wheel so that the first receives more force, and the second, respectively, less.

We have already mentioned the UAZ. Despite many similarities, it should be understood that the VAZ's all-wheel drive is made in the "pat-time" style. This means that when connected, the axles are firmly connected to each other, and the rotation occurs at the same speeds. Such a device imposes some restrictions on the use of all-wheel drive - the possibility of its use only in cases where road conditions allow slippage. In cases with solid asphalt roads and tracks it is recommended to transfer the car to mono drive mode.

Blocking differentials

Sometimes you can come across a misconception about why you need a small knob next to the shift lever on the Niva. Some car owners believe that it is needed to connect the front drive. However, front-wheel drive this car permanently connected. As well as the back. All-wheel drive is permanent for cars of the Niva family. The handle is actually used to switch the operating modes of the transfer gear differential.

In the "forward" position, the work of the differential proceeds normally, but if you move it backward, the differential is blocked, and the forces from the motor go to the axle differentials, which makes the drive more rigid. It should be noted that there are also special types of locks for the front and rear axles.

In theory, when applied in conditions where a car is stuck, it will be able to overcome an obstacle if there is sufficient grip on at least one wheel. Differential lock in this case is best done before overcoming an obstacle, but should never be done after hitting a difficult area to overcome. This use of blocking will avoid wear and damage to the transmission.

A number of gears down

A common misconception that can be encountered is that shifting the rear handle can increase the power characteristics of the motor. But this is not true. It serves to change the gear ratio between the motor and the wheels. With its increase, the tractive effort on the wheels will increase. There is also a reduction gear in the dispensing mechanism.

Here its work can be controlled by means of the rear handle. When shifting the lever back, we will have a gear ratio of 2.135 - this is the low gear. It is recommended to engage such a downshift only when the machine is stationary and the clutch is depressed. Despite the fact that the manual does not contain such a restriction, it is not recommended for beginners and inexperienced Niva drivers to switch while driving, since the Niva dispensing mechanism is not equipped with a synchronizer.

To make driving your car comfortable, check out some important points:

1. The usual, standard front and rear handle positions are forward and backward, respectively. Driving in this mode can and should be carried out on areas characterized by an even and smooth surface.
2. Locking the differential by shifting the front handle to the rear position is best on slippery roads. Such a measure will give Niva stability. It should be understood that after overcoming the problem area, the handle will need to be returned to its original position.
3. As noted earlier, downshifting should be activated in front of a potential obstacle, but not at the time when the car is already stuck.
4. It should be understood that it is sometimes impossible to activate the lock when the car is stationary, even if you press the clutch. This may be because the clutch teeth are pressed against the gear teeth. In this case, you can try to activate the lock by starting a slow movement and performing a gentle turn. If problems arise with disengaging the lock, then it is recommended to follow the same procedure with the clutch depressed and a little shaking of the steering wheel.

Permanent four-wheel drive. Is this good or bad? The Niva's transmission is built in such a way that the torque from the engine is transmitted to the gearbox further to the Transfer case in which the cross-wheel differential is installed. which divides 50x50 torque between the front and rear axles. then the moment is transferred to the front and rear axles, the differentials of which also divide the torque between the 50x50 wheels. The even distribution of torque allows the all-wheel drive to work flexibly. In the normal state, when one of the wheels is suspended, the torque to the suspended wheel will be transmitted 4 times faster due to the two two differentials. That is, if the car is stuck and one of the least loaded wheels hangs out, it does not matter whether the front or rear wheels rotate 4 times faster than the prescribed speed. If we admit the rotation speed in the first gear of 20 km h, then at the output the wheel will give out all 80. The transfer case provides a rigid center differential lock, which allows the synchronous transmission of torque to the front and rear axles, that is, to include a permanent hard four-wheel drive.

Moreover, if there is a diagonal hanging, then the moment will be transmitted to the front and rear wheels, which have less grip with the soil. Accordingly, due to the differentials, the rotation speed of these wheels will be doubled. The transfer case also has a reduction gear that increases the torque transmitted to the axles and decreases the rotational speed.

Two short levers, the first closer to the panel is the center differential lock, the second is the downshift. So that's why I'm writing this. Niva has one property. she is on slippery road if the differential is not locked, it can suddenly turn around and lose control. Moreover, this happens instantly, even experienced driver does not have time to react to such a somersault. Why am I writing about this. There was a time when I worked at Niva and carried mail around the area. Studied her habits up and down. Of course, she has excellent cross-country ability, even with the differential not locked. When driving and accelerating, the torque is distributed along the floor along the axes. And just hanging one of the wheels can stop the movement. But in the field, the long-travel suspension and the wheels almost always have traction with the ground, therefore, the redistribution between the wheels occurs evenly and the four-wheel drive works as expected.

Niva perfectly overcomes mud, sand, snow drifts. And almost any rough terrain. But this article is not about the all-terrain capabilities of the car, but about the control features in slippery times. Namely, a knurled winter road, ice, soil with low adhesion.

I have repeatedly found myself in a situation of a complete turn of the car on a slippery road, and if the car starts to turn, this cannot be changed, it cannot be corrected by steering and adding gas. Especially if it happens at a sufficient speed. fractions of a second and the car goes back to front. The driver does not even have time to react. But this is in the event that the differential is not blocked. Although the four-wheel drive is always on! Such a somersault is the norm. And now I want to substantiate this fact. What is the reason for this?

For this, a little excursion and comparison with other drives. And let's take rear-wheel drive, for example. On the example of the classics 2101-2107

Rotation is performed only on rear wheels... In slippery times, you have to work very carefully with the gas pedal, a small mistake causes a slip into slipping, and at this moment, when maneuvering or hitting one of the wheels, the car can easily turn around. Moreover, the engine located at the front of the machine loads the front axle. A light tailgate does not load the drive wheels, as a result of the lack of grip and load on the leading axle, the wheels skid.

But drivers are adapting. Winter tires + Ballast in the trunk of 50-60 kg and you can move. Skid when rear wheel drive occurs both during acceleration and during gas release. But drivers know these habits. Therefore, you can adapt and everyone drives like that.

Front-wheel drive on slippery roads is much preferable to rear-wheel drive. The drive wheels are loaded with the engine + they also pull the car behind them into a turn. The only difference is that when entering a turn, do not throw off the gas, otherwise the back can be thrown and the car will turn around.

And so returning to the full drive to the Niva. When the center differential is turned off, the torque between the axles is divided in half. But the load on the front and rear axle is different. Pre-loaded with engine gearbox and transfer case. the rear of the car is short on the rear axle, the load is less. Now imagine a situation of driving on a slippery road. The driver is completely confident in himself, All-wheel drive is always on, what to fear. when driving and accelerating, everything is fine. The car rides confidently both on slippery roads and uphill. But then the driver threw off the gas before the obstacle and wagged the wheel a little. The rear wheels, which are already less loaded, transfer part of the load to the front wheels under the gas discharge. The front wheels have good grip and make friends. By resting, they slow down the movement of the car, but through the center differential they redistribute part of the load to the rear, as a result, the force directed to the unloaded rear wheels. I repeat, the car is braked by the transmission! Engine speed drops and is a brake. To continue, through the good grip of the front loaded wheels, moment is transferred back to the transmission; the wheels make the engine spin while it slows down. But there is between the axle differential and it is not blocked, which means that part of the energy goes to the rear axle, and that either the engine will spin up or the rear wheels will start to slip, and as soon as the loss of traction begins, the wheels will first slow down the rotation then the torque will easily be transferred from the front axle on the rear and rear wheels will have a braking effect. While the front wheels will spin without blocking, the rear wheels will spin as well, but at a lower speed in error on the front differential. In the end, what does this mean? Complete loss of adhesion rear axle with the road. It's just a sleigh. Therefore, with any maneuver, the car will instantly deploy and there is nothing to be done about it. The peculiarity of such a transmission. Therefore, on slippery surfaces, it is imperative to block the center differential. Then the torque and braking torque is transmitted rigidly to two axles and the machine has good stability.