Low gear - what is it?

Given the great popularity of hydromechanical automatic transmissions, manufacturers manufacture this type of transmission in such a way as to achieve maximum user convenience and versatility. At the same time, there is also the task of reducing fuel consumption.

As you know, the most common today is a simple four-speed automatic. As a rule, these gearboxes have several standard and understandable operating modes, which greatly simplifies operation.

However, on many automatic transmissions, in addition to the basic ones, you can also find additional modes. In this article we will talk about what overdrive is on an automatic transmission, how overdrive on an automatic transmission is turned on and off, why this mode is needed and when it is used.

How to brake with a manual engine correctly

The deceleration mode of the engine and gearbox depends on the situation in which the car is located. More precisely, on the conditions of the road surface. For example, when driving on a flat road, engine braking will be different from driving down a mountain or on ice. Let's look at each mode in detail.

Rectilinear movement on a flat surface

These are the most ideal conditions. Drive along the highway in fifth gear. There is a turn or obstacle ahead. To apply engine braking, just release the gas pedal without pressing the clutch or changing gear.

The power unit remains in rigid coupling with the driving wheels of the vehicle. Since the fuel supply stopped when the gas pedal was released, the engine begins to “consume” energy. Torque is transmitted through the gearbox from the wheels to the crankshaft. Due to friction in the internal combustion engine and compression in the cylinders, this moment gradually fades away and the car begins to slow down smoothly. All this happens without the participation of brake mechanisms.

If at this moment you “squeeze” the clutch, the connection between the gearbox and the engine will be broken, the internal combustion engine will go into idle mode and the braking process will be interrupted. To continue it again, you need to smoothly move the clutch pedal until it “snaps” and release it. Don't forget about the speed of the car. If it is less than 20 km/h, the engine may stall. Therefore, it is recommended to use this maneuver at high speeds.

Let's go down the mountain

When descending a mountain, it is recommended to brake with a manual engine in lower gears. As mentioned above, if you do this in high gear, the efficiency will be low, the car will slow down smoothly and there is a chance that it will not fit into the turn. This is especially true on mountain serpentines.

To downshift:

Depress the clutch
Downshift
Use the gas pedal to raise the engine speed to 2500-3000 rpm. Smoothly release the clutch pedal. This way, you will “bring up” the engine speed to the speed of the input shaft of the manual transmission and there will be no impact on the clutch disc. You will protect the mechanism from damage
Release the gas pedal. You started to slow down with your engine.

A case from one's life. I had the opportunity to travel to the New World along the Crimean serpentines, where the descent was replaced by a sharp uphill through a sharp turn. I was driving in third gear, which was enough for me to use the brake pads minimally and slow down in time before the turn. Unfortunately, on such turns I often came across cars in a ditch - these were those who neglected the recommendations for effective braking with the gearbox and engine in mountainous areas and frequent use of the brakes.

We brake the internal combustion engine on ice or compacted snow

Engine braking on slippery roads in winter is an important skill that will protect you from skidding or drifting. It differs from the two modes described above. It is worth remembering that there is ice under the wheels, so the car’s behavior will be different.

Rules for how to properly slow down with a motor on ice:

Do not suddenly release the gas pedal. This will lead to wheel slip and loss of traction.
Do not release the clutch pedal sharply when switching to lower gears during engine braking. The car may skid. Because the wheels will sharply transmit torque to the motor, and since there is ice under them, their rotation speed will quickly drop. This is the equivalent of slamming on the brakes.

When to use it

Experts and manufacturers recommend turning on the overdrive mode in the automatic transmission in the following cases:

when accelerating the car, for example, when you overtake and move over 100 km/h;
when you are driving on a bad road or even off-road;
you are slipping a heavy trailer.

Despite many different opinions, it is also recommended to turn on overdrive in the city. This will not be difficult; the button on the lever will do it for you. The button is called O/D (on|off).

When this mode is turned on, this means that the automatic transmission will independently and sequentially shift from 1st to 4th gear. Afterwards, it will turn on the torque converter lock and make a push, do not take it as a transition to 5th speed, it is not. When driving at speeds of about 40 - 60 km/h, it is not recommended to use overdrive. Also turn it off if you are in traffic. After pressing, a special button will give a signal and the yellow light will light up. It is also recommended to turn it off when:

you go up and down (long descent);
when the pace of traffic on the road is constantly changing;
if you drive less than 50 km/h.

It is also recommended to turn it on when:

you are driving on the highway;
eat for a long time without changing speed;
you drive at high speeds, for example, over 120 km/h.

Off mode is displayed on the control panel

Gear Modes

Let's take a closer look at how to use the transfer case on a Chevrolet Niva. It serves to switch to a lower gear and also blocks the center differential; this can be done at the same time. In order to engage a lower gear, you need to shift the lever to the right and up; to lock the lever, you need to pull it to the left all the way. The handle has the following designation:

Low(L) - decrease;
N-neutral;
High(H) - normal, increased.

Low gear is engaged at a speed of no more than 5 kilometers per hour, or after a complete stop. In order to overcome a steep climb, or when driving where there is soft ground, so that the vehicle speed is minimal and at the same time stable, a lower gear must be engaged in advance. For example, if you are driving on a flat road in second or third gear, and a bad section of road appears in front of you, you need to stop and shift to a lower gear.

It is not recommended to turn on the center differential at high speed, since the car may skid strongly at the moment of switching. It is advisable to block where there is a slippery surface and the wheels begin to slip.

These include:

Switching the transfer case should only be done when the car is not moving.
You can also engage the differential while the vehicle is moving.
You can switch to a lower gear while the car is moving.
To ensure long-term and uninterrupted operation of the differential, it is necessary to periodically turn it on, especially in winter. This should be done once every 7 days.

Among domestic car enthusiasts, the Chevrolet Niva is a fairly popular SUV that appeals not only to fans of extreme driving, but also to fans of measured driving outside the city. Many people know that one of the features of a car of this brand is the presence of a transfer case in it.

Using this unit, you can enable downshifting, locking, or two functions at the same time, depending on the conditions. The question of how the Niva Chevrolet transfer case should be used correctly is of interest to many happy owners of such a vehicle and those who only intend to purchase it.

It should be immediately noted that you can engage both the lock and the transmission at the same time using the Chevrolet lever that changes gears. So, the lever shifts to the right, and then immediately up to engage a lower gear. To switch back to higher, the lever should simply be moved back.

Using a Niva Chevrolet transfer case, in addition to the above, neutral gear is also engaged, while the car will remain reliably in one place. The lock can be engaged at any time - in normal gear, in low gear - just switch the Chevrolet lever to the left.

This mechanism can operate in five modes:

Neutral is on.
The differential is unlocked when the "lowering" is turned off. In this case, the torque is distributed in a ratio of one to two.
The differential is locked when overdrive is engaged. Here, torque distribution is carried out automatically, depending on the quality of wheel grip on the road.
Downshift is engaged and the differential lock is disabled. The transfer of forces occurs in the same ratio as in the first case.
The differential is locked and the gearbox is engaged. In this case, all axles are rigidly locked together, including the axle shafts. Torque is produced unevenly, depending on the type of road surface (dirt, sand, etc.). In this mode of operation, the best cross-country ability of the vehicle is achieved. But driving with a constantly engaged downshift and with locks will not work. This increases the load on the transfer case bearings. The Chevrolet Niva will soon require serious intervention in the transmission. Fuel consumption also increases significantly, which greatly eats up the tires.

Extending the life of automation

First of all, the performance potential of the automatic transmission is determined by careful operation. An important factor that prolongs the durability of the mechanism is timely and high-quality maintenance.

The duration of a comfortable ride on an automatic transmission will be longer if you constantly monitor the oil level in the box. Using a dipstick from the engine will help sort this out. The main thing is to prevent leaks by changing the oil and filter. It is advisable to do this every 40–60 thousand km. Also, do not save money; it is better to use the original product.

In terms of operation, automation is many times more complex than mechanics. Moreover, such a transmission is more suitable for traveling around a metropolis. There’s just a nuance: the machine doesn’t like high overloads. Do not torture the system until it warms up. This is especially true in winter.

Once you change from a manual to an automatic, you can confidently say: you won’t change back.

Source

Overdrive is... What is overdrive

Large English-Russian and Russian-English dictionary. 2001.

rise in price
step-up substation

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Why is low gear needed?

So, let's look at the example of an SUV. In this case, a reduction gear can significantly increase the vehicle's cross-country ability. In simple words, the presence of a downshift allows such a car to drive where cars with a conventional gearbox are not able to overcome the obstacle and continue driving.

Simply put, a low gear in the transmission allows the wheels to spin at a lower number of revolutions, while the engine operates in the standard speed range. This opportunity arises due to the fact that the transmissions of such cars use a transfer case (transfer case). In the transfer case, torque is distributed along the axles of the drive axles of the off-road vehicle.

To make it clearer, you need to pay attention to the following. Typically, the power unit produces maximum power at a certain number of revolutions

Also, at certain speeds, different from the speed of maximum power, the maximum torque is achieved, which is transmitted through the transmission to the drive wheels.

So, usually gearboxes are designed so that the engine delivers maximum torque and power fairly evenly at different speeds. The first gear allows you to move away, and in this gear the “emphasis” is on maximum torque, while in the 5th gear the car can move at high speed at maximum power speed.

For standard road conditions, such features of the gearbox are quite sufficient, but if it is necessary to overcome obstacles, difficulties arise. The fact is that, for example, when trying to drive uphill, and the surface is slippery or loose (snow, ice, mud, sand, softened soil), the torque in first gear is too high.

The result is that when you press the gas pedal, the car “buries” its wheels in snow or mud, slips and cannot continue moving. If you switch to second speed or higher, the engine will simply stall, since it does not have enough revolutions and power to overcome the difficult section.

It turns out that in a situation where you need high engine power (high speeds), but also need a smooth ride at low speeds and low wheel speeds, a conventional gearbox is powerless. It is with these features in mind that SUVs receive a transfer case with a low gear.

So, active low gear has a high gear ratio. This allows you to reduce the wheel speed and at the same time spin the engine to maximum power speed. As a result, the car is able to move at low speeds at maximum power speeds. This feature is indispensable on off-road terrain, when driving uphill, on steep descents, etc.

Purpose of double squeeze

Mechanisms such as synchronizers facilitate the process of gear shifting, making it smooth. At the same time, wear is reduced and the specific grinding noise characteristic of older models is also eliminated. If there are no synchronizers or they are broken, you cannot do without double squeezing.

So why is it really needed? The need is due to the equalization of engine speed by gears and shafts. Otherwise, these parts may jam at best. In practice, this happens as follows: moving at first speed, the engine speed is increased to three thousand revolutions. To switch to second, you need to release the gas, squeeze the clutch, go to neutral. Then wait until the speed drops and press the clutch again, switch to second. In this way, the shafts are equalized without damaging the gearbox. Then you can move on calmly.

In the case of re-gassing, the process is a reverse action. This implies reducing the gear without putting the gearbox to sleep. If you need to turn on the road, but it is impossible to do this in fourth gear, you must slow down and lower the gear. Otherwise, there is a risk of stalling. You can smoothly release the gas by squeezing the clutch and move to neutral. The next action will be to gain momentum. To do this, you will have to activate the gas pedal, in other words, make a shift. That's it, after that we managed to increase the speed. Synchronization with the shaft has occurred. You can now downshift and continue driving.

It is recommended to adhere to the throttle pause at neutral during the process. The main thing here is to catch the right clutch moment in time to prevent the car from stopping. Skills come with experience, of course. Therefore, there are no special skills or secrets here.

The question arises: why is this necessary when modern cars are equipped with synchronizers? If you remember that often the road is not perfectly smooth, there are always some obstacles.

Therefore, synchronizers may fail on the first bump or climb. This is where re-gassing comes to the rescue. For example, when going up, you realize that this transmission cannot pull you through. There are simply not enough revolutions, the throttle is overloaded. This allows you to switch to a lower gear without losing the necessary inertia.

Why do you need a gearbox with low gear?

Let's imagine a situation where, during a long climb in third gear, the engine does not have enough power to overcome an obstacle, and when switching to second gear, the number of revolutions is high. Then the downshifts come into effect. The car starts to move at high speeds, but at low speed. At the same time, engine power increases, and overcoming road obstacles becomes easier.

When the engine does not have enough power to overcome an obstacle, a reduced automatic transmission speed helps

A low-range gearbox increases torque at the wheels. The gear ratio of the secondary shaft increases, which in turn increases the speed of the axle. This property of the box is especially useful when overcoming small water obstacles, driving in icy or wet road conditions, especially on descents and ascents. And also when driving on “strong” off-road conditions, when in normal mode there is not enough power.

Downshift on SUVs Video

Turn on the "lower"

By starting a low-range gear, a large torque is transmitted to the wheel drive. As a result, difficult roads can be overcome without serious load on the engine.

This mode is not the only one on modern machines. The driver can also select other operating modes. You can save fuel while traveling on highways by switching the gearbox to high-speed operation. We often encounter the problem of traffic jams; in such a situation, it is logical to switch the gearbox to a mode not exceeding first gear. Typically this setting is used when driving at low speeds.

Why is low gear needed?

To make it clearer, you need to pay attention to the following. Typically, the power unit produces maximum power at a certain number of revolutions

Also, at certain speeds, different from the speed of maximum power, the maximum torque is achieved, which is transmitted through the transmission to the drive wheels.

Why is the reduced automatic transmission mode useful and how to use it correctly

Types of gearboxes have certain advantages and disadvantages. In the case of an automatic, it is more suitable for driving on city roads where moderate speed is required. Speaking of mechanics, there is good efficiency, thanks to which the driver feels his car to the fullest. It happens that when overcoming hills, it is difficult to choose the optimal gear. If you switch to third, the engine does not have enough power. When the second one is turned on, there is excessive thrust, leading to excessive engine consumption. This is where you can’t do without a lower gear.

Low gear - operating principle

The low gear is part of the transmission and is mounted directly into the transfer case. It is there that the torque from the engine is distributed on the axis of the drive axles of the SUV.

Engines develop their full power at a given number of revolutions, and all torque is transmitted through the transmission to the drive wheels (each unit has its own speed threshold, at which it produces maximum torque). An ordinary gearbox is made so that the engine transmits all the power correctly and evenly at various speeds at which the car moves. For example, in first gear you can move away at a speed slightly higher than standard idle (for example, about 1000), and in fifth gear you can reach a high speed of several thousand. As a rule, engines develop their maximum power at just a few thousand revolutions. For some engines it is 2.5-3 thousand, for another it is under 6 thousand. It will not be possible to drive in first gear at such high speeds, so the engine power when driving will be far from maximum.

Consequently, it is no longer possible to drive onto a high obstacle - the engine will stall or the wheels will slip. The same is true when driving through mud, snow and other similar obstacles. In other situations, high engine power is required, but leisurely and careful driving is required - for example, on a rocky road with a cliff.

This is where downshifting comes in handy. And not only in these, but also in many others. What happens when you turn it on? Active low gear has a sufficiently high gear ratio, which allows the wheel speed to be reduced at maximum engine power. So it turns out that at low speeds the car operates at maximum power, which, with the proper approach, provides a huge advantage off-road, when climbing a steep slope and in other driving conditions.

Downgrade or accessible about complex

In our difficult age of nanotechnology and oil production in the Arctic, happy owners of “jeeps” are beginning to get used to turning on all-wheel drive with a beautiful button on the dashboard and rejoicing like children that they have a “real” SUV, but as soon as most of these monsters drive off-road from the asphalt, the owners begin remembering such an atavism as the lowering and swearing loudly at the overheated viscous coupling.

But you and I are real jeepers and we know that without lowering it’s not a jeep at all and life is bad without it, and that’s why when choosing a car we prefer, even if it’s from the last century and rotten like last year’s tomato, but still a real jeep. Not so long ago, in the process of building an iron horse, I had to delve into the question of what and why and with what it is eaten. Everyone talks smartly about some kind of Newtons, by the way, they like to mention them in test drives of any cars with such an air, as if the average car enthusiast is simply obliged to know how they affect the behavior of the car. Looking ahead, I will say that these numbers will not say anything if there is no understanding of what will ultimately reach the wheels. What got me the most was the arguments of more experienced comrades about which lowering of the transfer case is better: 4.16 or 4.9. For me personally, these are just numbers and there is no more meaning in them than in data on the population of Argentina. Strange numbers and clever words made my head spin and I wanted a button on the dashboard, instead of all this abstruse bullshit. But this is not our method, so I decided to figure out what kind of garbage this is and started studying the issue, in the process this article was born, since not a single sane source was found where the simple story was told, or rather, they were found, but they also wander into “abstruse distances” . I will try to explain everything as simply and clearly as possible. Let me make a reservation right away that in all calculations there will be many assumptions from the “let’s take one white horse in a vacuum” series, in particular we will not take into account friction losses, efficiency of units, etc., otherwise the formulas and calculations will be very long, whoever needs exact numbers will figure it out himself, we We will limit ourselves to a “general overview under ideal conditions.” So, take a deep breath and let's go!

We will assume that everyone knows the general principle of operation of the gearbox and there is no need to explain it, but if anyone is not in the know, then its task is to transmit the rotation of the engine, transforming it, depending on the selected gear, to the driveshaft, and then to the gearbox and wheels. But for driving without roads, it often turns out that “it would be necessary to lower it”; for this purpose they install a transfer case, that is, essentially another intermediate block of gears, which allows you to once again convert the rotation and lower the rotation speed. How it works? The simplest and most understandable example is a bicycle. Ever ridden a bike with a derailleur? Remember how it feels when the biggest gear is in front and the smallest in the back? It is very difficult to move a bicycle, but if it is moved, then for one revolution of the pedals it makes several revolutions of the wheel and flies like an arrow. What if it's the other way around? Yes, yes, you pedal in the soap, and the bike crawls like a turtle, but it crawls uphill and through mud and anywhere. Well, it’s the same with the lowering gear, only the engine works instead of you. In a lower gear, the load on the engine becomes noticeably less, and so does the speed, but it creeps anywhere and anyhow.

But on a bicycle everything is simple - two gears, on a car it’s also nothing complicated, but there are more gears and in almost every node the rotation is converted by one value or another. But let's take things in order. First, our engine spins a LARGE gear, which is called a flywheel. In the picture below, it's the big gear on the right.

Then this rotation is transmitted to the gearbox, then to the transfer case (if there is one), then through the driveshaft to the differential and then to the wheels.

Now mathematics and physics

As soon as you start to understand the question, some scary numbers come up that the interlocutors operate with, and you, like a fool, don’t understand anything, but you’ve already realized that this much percentage reduction is cool, and if 1k is still a certain amount, “it’s a tractor” , and at the same time it can be lowered in bridges. All these conversations begin when the question of real off-roading arises, when the standard lowering is no longer enough to rotate the wheels from the tractor, which you, having seen enough of more experienced comrades, put on the car for some reason.

So, let’s try to figure it out together, using the Suzuki Jimny as an example.

Let me make a reservation right away: the numbers are approximate and taken from the Internet, I could be wrong. To begin with, we open the manual and find the following data:

— Gear ratios in the gearbox - Gear ratios in the transfer case - Gear ratios in the differentials

We also need torque on the internal combustion engine and wheel diameter. Specifically for a gym bike it looks like this:

— In standard differentials (gearboxes, call them whatever you want) it is 4.3 (although there are others) — Also from the book, the maximum torque of the Suzuki Jimny is 110 Nm at 4500 engine speeds.

The question remains of the wheel diameter. You can simply measure with a tape measure or calculate using the formula.

The standard Jimny wheel size is 205/70/15. This means that the wheel diameter is 2 profiles + rim diameter = 205mm x 70% x 2 + 15 x 25.2 = 665mm or approximately 26.4 inches.

Well, it seems like we’ve stocked up on all the initial data and are starting to calculate the scary numbers. Although no, before bothering your head with this garbage, you need to explain why it’s all. And this is necessary so that you can better understand the physics of vehicle movement and be able to calculate the optimal reduction under increased loads. After all, the manufacturer did not at all expect that its products would be stuffed glass deep into the swamp and, accordingly, if you want greater cross-country ability without damaging the units, then you should think about lowering the standard values.

To begin with, we have an engine that transmits rotation to the gearbox; at what frequency it rotates we can see on the tachometer. Then we delve into the performance characteristics of the gearbox and find out that in first gear the reduction is 2.962 (for the AT gearbox), that is, at the output after the gearbox, the driveshaft will make almost three times less revolutions, roughly speaking, for 1000 engine revolutions we will get 337 driveshaft revolutions shaft Next comes the transfer case with a reduced gear ratio of 2.145, that is, behind the transfer case we already have 157 revolutions, and then we go to the axles, to the main pair, which has a reduction of 4.3, with a total output at the wheels of 36.5 wheel revolutions per minute per thousand revolutions on the engine. The total reduction is: iob=2.962×2.145×4.3=37.32

We can also calculate the torque at the wheels - this characteristic is much more real than abstract horsepower or engine torque.

You can understand what torque is using a simple example. Let's take a stick and clamp one end of it in a vice. If you press on the other end of the stick, a torque (Mkr) will begin to act on it. It is equal to the force applied to the lever multiplied by the length of the force arm. In numbers, it looks like this: if you hang a 10-kilogram load on a lever one meter long, a torque of 10 kg*m will appear. In the generally accepted SI measurement system, this indicator (multiplied by the value of the acceleration of gravity - 9.81 m/s2) will be equal to 98.1 N*m. It follows from this that more torque can be obtained in two ways - by increasing the length of the lever or the weight of the load.

The motor produces torque Mdv. After conversion by the transmission, this moment is transmitted to each drive wheel of the car in the form of Mk and forces the wheel to rotate, i.e. it creates a shear force Fct = Mk/R at the point of contact of the wheel with the road, and this force is applied to the road through the wheel. The road surface prevents the wheel from rotating by a frictional force Fрт of the same magnitude, but applied to the wheel and directed in the opposite direction. To show that forces act on different objects, the points of application of forces in the figure are conditionally slightly spaced vertically:

This friction reaction force Fрт, multiplied by the number of driving wheels, moves the car. In relation to jimny, the accelerating force will be 4Fpt. Let's determine this value. The engine develops maximum torque Mdv=110 N.m at 4500 rpm. This means that in first gear in the gearbox with all our downshifts:

4Mk=Mdv.it=110×37.32 = 4105.2 N.m.

With standard size wheels, the traction force of all four wheels will be:

4Frt=Mdv.it/R=4105/0.332=12364 N=1236 kg.

That is, a little more than a ton. For comparison, for 1st gear without downshifting it will be only 557kg, and for third gear 437kg

Well, in general terms we figured it out. Of course, in real conditions, all these figures vary greatly depending on the relief, soil and other factors, but at least in general terms it became clear what and why. Again, if you want to lower the gear ratio in the transfer case or main pairs, now you can substitute your numbers to calculate what can come of it. In general, it is believed that for cars that conquer severe off-road conditions, the overall gear ratio should be from 50:1 to 80:1 with a manual transmission and from 40:1 to 70:1 with an automatic transmission.

So turn it down and go!

PS When writing the material, all sorts of different sources were used, in particular this one. I highly recommend it for those who want to delve deeper into the issue from the point of view of the physics of the process.

Source

Gear housings

Standardized cast gearbox housings are widely used in mass production. Most often, in heavy industry and mechanical engineering, housings are made of cast iron, less often of cast steel. When it is necessary to make the design as light as possible, light alloy bodies are used. The gearbox housing most often has attachment points - paws and/or ears, by which the gearboxes are moved and/or secured to the base. At the output of the shafts, seals are placed to prevent oil leakage. Structural elements are often placed on the gearbox housings to prevent an increase in pressure inside the gearbox resulting from the heating of the gearbox during operation.

In piece production, welded housings are widely used, allowing for individual design solutions.

Features of use

If the downshift does not engage, you should slow down the car, but it is best to make the connection before you start driving. When the clutch is depressed, the corresponding lever is moved to the required position. New cars have the ability to turn on electronically using a special button.

When using such a transmission, you cannot move on a hard surface, since the transmission will be subject to significant load at this time. To achieve maximum effect, you need to start at higher speeds.

It is important to monitor the clutch. Despite the fact that there is a decrease in the load on it several times, due to inexperience, damage can be caused by a sharp lowering after the engine reaches maximum speed

The low gear has a certain number. As it increases, the car begins to move more efficiently, regardless of the speed.

Forced locking of the cross-axle differential on Niva

The VAZ SUV was developed as a car for the village.
At the time, it was said that additional interlocks would complicate the design, making it more expensive and less reliable. In addition, the Niva already has good cross-country ability. This is probably correct. However, in a country where the percentage of paved roads out of the total number is relatively small, we want more. Various small and large enterprises took advantage of this, mastering the production of differentials with forced locking. The following should be noted immediately .

Installing forced-locking mechanisms on the Niva instead of standard differentials significantly increases the load on the axle shafts and transfer case, which can lead to their premature failure.

And, nevertheless, since such a rework is possible, it is necessary to say a few words about it. Currently, the most common differentials are:

With pneumatic connection;
With electrical connection;
Self-locking.

Briefly - the advantages and disadvantages of each of them.

Pneumatic connection.

The wheels are locked from inside the car using compressed air. In this case, a silicone hose is laid to the car axle. The device is quite reliable, but requires additional expensive equipment. A set of hoses, a compressor and a receiver are sometimes more expensive than the differential itself.

Electrical connection

The differential gear is locked by a cam mechanism, which is activated by electromagnets. The device is reliable and does not require maintenance. The downside is the high current consumption, which places additional demands on electrical equipment.

Self-locking mechanisms

Their operating principles are different. Some are blocked at the slightest slip, others when the load on the wheels increases. However, regardless of the design, they do not require human intervention, and therefore are popular among SUV owners. But their main advantage is that they do not have such a rigid locking as all other types, which means they partially remove additional load from the axle shafts.

What are digital nomads like?

A prerequisite for digital nomadism is having a job that can be done from anywhere in the world with a stable and fast Internet connection. A digital nomad can be officially employed by one company, or be a freelancer with many clients, or even have his own business.

Our people go to the bakery by taxi

Banks and experts note changes in consumer standards

The main thing is that digital nomads are people who use technology to make a living while traveling. At the same time, they can either change host countries one after another, or lay low for some time in a place they like, if the visa regime allows.

Tuning – “How an ordinary Lada was turned into a sports car”

Off-road without reduction

SUV with reduction gear KIA Sorento

In recent years, the trend towards increasing the civility of SUVs and crossovers has acquired a scale that is depressing for experienced jeepers. Real SUVs are chasing comfort, which leads to an increase in their prices, and often to a decrease in cross-country ability and closer proximity to crossovers. Crossovers, in turn, are becoming more and more similar to asphalt machines. There are practically no frame SUVs left. Many people part with downshifts. Following the flagships, other SUVs are also becoming lighter. So the KIA Sorento has remained without a downshift since 2009. What can we say then about crossovers! The Porsche Cayenne S with a 6-speed Tiptronic S transmission has a reduction gear, but since 2010 the Porsche 958 Cayenne has received a new version of Tiptronic with 8 steps, but without a reduction gear. The designers of the Audi Q7 also abandoned downshifts. A general trend is visible, the paradox of which illustrates the “spiral” nature of development. Modern crossovers, or rather that part of them that has some claims to the title of SUV, are simply supplemented with 1-2 steps in the gearbox. The transmission of a quite “budget” Renault Duster is designed in such a way that it is better to start on the asphalt in second gear, and leave first for driving on questionable roads. Actually, their designers repeat the line of thought of the LuAZ developers. Only with other tasks. The buyer is inclined to pay more for comfort than for the capabilities of the car. This is probably a real change in the needs of the majority of motorists. And for true connoisseurs of free movement in different directions, there remain the indestructible simple cars of the last century and the off-road supercars of the new century.

https://youtube.com/watch?v=koKbdJUwEZ0

What's the result?

As you can see, low gearing in a car that is positioned as an SUV is a necessity. In this case, the efficiency of the reduction gear itself will depend on the gear ratio.

Finally, we note that the driver must also be able to use downshifts correctly, since errors can lead to breakdowns of both the transmission itself and, in some cases, the car engine itself.

All-wheel drive device, types and types of all-wheel drive, diagram of the drive device on all-wheel drive cars. All-wheel drive boxes, features.

Gearbox differential: what is it, differential design, types of differentials. How does a gearbox differential work in a car transmission?

Which gear to choose and what is the correct shifting algorithm is a seemingly trivial question, but only for those who are used to driving a manual transmission and have been doing this for quite a long time. The note is intended for those who intuitively have switching skills. To gain basic knowledge, I recommend that you first read the note.

Dependence of transmission on drive

Design features vary for different types of transmissions. In total there are the following drive types:

Front wheel drive.
Rear wheel drive.
All-wheel drive.

There is such a thing as a car wheel formula, which includes 2 digits. Explanation: the first is the total number of wheels, and the second is the number of drive wheels. So front- and rear-wheel drive are designated 4×2, and all-wheel drive – 4×4.