LSD-differential - what is it?

Every motorist seeks to learn about his car as much useful and important information as possible. Naturally, if you do not know what a differential is, you can still drive. But this is all over - you will not be able to do more, but many motorists prefer to repair their four-wheeled friend on their own. Moreover, drivers have their own private community, and you can hardly get into it if you have no idea how your car works. It is for this that you need to study absolutely all the little things, since they may well come in handy in the future.

And in this article, the LSD-differential will be considered in detail. What it is? How does he work? What kind of species does it have? On all these questions you will find the answers in the process of reading the article about the LSD-differential. What it is? This is the first question to which I would like to find the answer, but do not rush. First of all, you should know what a differential is in principle, if you do not know it. If this information is already known to you, then you can simply refresh your knowledge before proceeding to the main part of the article.

What is a differential?

So, the main theme of this material is LSD-differential: what is it like, how it works and so on. But first you should still learn about what is generally a differential. Many car enthusiasts already know the definition of this concept, but if you still do not know it, then this information will become very important for your further study of the topic.

The differential in automotive terminology is the mechanism that forms part of the transmission. It serves to transmit power, but it has one interesting feature, because of which it received such a name. The fact is that the power in the differential is divided in the process of rotation or into two differentially connected flows, or two power flows are summed into one. It is worth paying attention to the fact that the two power flows are interconnected in a differential manner, that is, in the sum they give one hundred per cent of the capacity, but they do not have a specific indicator. In other words, they can give both 50 to 50 percent power, and 70 to 30 percent, and 100 to 0 percent, and vice versa, 0 to 100 percent power.

Well, this is basic information about the differential itself. However, the topic of the article is slightly different, so it is worth considering the issue. The subject of the article is the LSD-differential, what is this, how does this mechanism work and what kinds of it are there. This is exactly what will be discussed later.

Self-locking differential

The differential friction differential LSD is self-locking, and it is significantly different from the classic version. What are the differences? The fact is that with the appearance of a large difference in the speeds of rotation of the axle shafts of the wheel drive, a lock is activated, which makes it possible to solve the problem as quickly and efficiently as possible. The simplest example is the skidding of the front or rear wheels, it was the primary reason for the need for changes in the classical differential. When any of the axes starts to scroll due to the fact that the wheels can not overcome this or that section of the road, the self-locking differential can become a real salvation.

Naturally, for smooth and smooth pavement you do not need such a lock - however, this is another reason why you pay more attention to theory. After all, there are differentials with different types of locking, which are suitable for different cars, as well as for different road surfaces and conditions. That's why you should study more carefully what the differential LSD is.

Abbreviation

You have a general idea of what the LSD differential is, but if you are asked what these three letters mean in the title, what can you answer? In fact, everything is quite simple - this abbreviation stands for Limited Slip Differential, which can be translated in different ways.

One option has already been mentioned above - the differential of increased friction, but one can often find another - a differential with increased internal resistance. Both options are correct, and if you use any of them, you will most likely be understood. But it is much easier, of course, to use the abbreviation LSD, since it is universal, capacious and understandable to everyone.

However, it's all just theoretical data - it's time to figure out how the LSD differential works and start with its comparison with the classic analog.

Comparison of the differential LSD with the classical

The classical differential also has several names, each of which is used quite widely. It can be called standard, open and even free - and its distinctive feature is the fact that it has the permissible possibility of a difference in the angular speeds of the output shafts. What does it mean? This means that each of the output shafts can work either one hundred percent or zero percent. And this, in turn, means that one of the shafts may even stop. This can easily be seen when driving, when one wheel is at full power, and the second does not spin at all.

How does the LSD differential handle this problem? The principle of operation of this mechanism is extremely simple: it has an automatic blocking system that allows for a difference in the power of the two streams, but small enough, for example, 60 percent by 40 percent. However, when this difference exceeds the allowable limits, a blockage occurs, which protects the car from the negative consequences of such a phenomenon. The work of the LSD-differential is most noticeable in off-road vehicles, as well as in sports cars.

Where is this device used?

As you have already understood, for each type of cars there are their own differentials and ways of blocking the difference in power. If you drive a car on a smooth and smooth paved road or road, you do not need to worry about the problem described above. As it was said before, the most suitable such differential is in off-road cars and sports cars. If you drive an SUV, then, most likely, you have to move around the rough terrain, where the chances are high that your car will start slipping. And to avoid this, as you already understood, you need a high-quality differential lock.

The LSD version is ideal for this, evenly distributing power flows and not allowing one shaft to get all the power and the other to remain stationary. Approximately the same thing happens in the case when you drive a sports car. However, in this case, your goal is not to cope with the rough terrain, but to overcome the asphalt at the start.

If you at least once saw how the car starts at a high speed from the spot, you just noticed that the wheels at the start are scrolling - this is just due to too high a difference in power flows. The self-locking differential reduces this difference to an acceptable minimum, thereby minimizing the scrolling of the wheels at the start at high speeds. So, for example, the LSD-differential of the Subaru racing model will strive to maximally limit the difference between power flows, but without affecting the overall performance of the car.

Principle of operation

You already managed to get a general idea of how this differential works, but it's worthwhile to dwell on this moment separately. After all, the principle of work is what is the most important point in the whole understanding of the device. So, this mechanism initially works in exactly the same way as the classical one, power is supplied through two channels, however, there is a factory limit of the difference of these two capacities, which can be achieved in the course of the motion.

As a result, when an unforeseen situation occurs and the power of one stream begins to exceed greatly the power of the other, the same interlock operates. As a result, there is a redistribution of power, or rather, resetting it to a standard distribution, that is 50 to 50 percent. The normalization of the torque allows you to get out of the difficult situation. And in modern differential models, the lock remains active until the situation returns to normal, that is, until the contact with the road is fully restored.

Types of LSD-differentials

As it became quite clear, these mechanisms are far from the only cars in the world. However, they are also subdivided into species, which you should also consider in more detail. So, there are only two main types, but they work completely according to different principles. The first is a design that is based on the sensitivity to the speed difference, while the second is on the sensitivity to the difference in torque transmission. But is it really so great to pay special attention to this? It's time to find out about it.

The difference between LSD-differentials

So, if you have a choice between two mechanisms, one of which activates the lock depending on the difference in speed, and the other - depending on the difference in torque, which one should you choose?

It is worth knowing that the first kind is much more popular, it is used in most cars on which the LSD differential is installed. Therefore, it is still worth making a choice in favor of it. There are as many as two reasons. The first is that the differential works thanks to a design based on viscous coupling - a fairly simple mechanism that is easy to produce and inexpensive. Therefore, the price for such a differential will be lower, while a mechanical lock of the second type is more expensive in production and, accordingly, will cost more when buying.

The second reason is simplicity and unpretentious viscous coupling - you generally do not have to take care of it, and if something happens to it, the repair will be simple and inexpensive. If we consider the second kind of differential, the design there is quite complicated, it has a large number of details, so repairing the LSD-differential will be difficult and expensive.

Differentials sensitive to speed difference

Now it's time to look more closely at both these species, because they also have their division - as you see, this question is not so simple as it might initially seem.

So, the first version of the mechanisms, based on the sensitivity to the difference in speeds, is the viscous differential. You need to very carefully select the oil for LSD-differential of this type, since here an important role is played by a silicone gel, which should not be mixed with oil. To do this, viscous coupling, that is, the main reservoir of this device, is made sealed.

Strictly speaking, it is precisely because of the gel that one of the most important advantages of this type of differential is obtained - they work very smoothly due to changes in the properties of this gel. Due to it the gradualness disappears, which is the problem of many gearboxes. And given the fact that now the automotive industry is mainly aimed at improving the comfort of the driver and passengers, this property has proved to be very important.

However, do not think that this type of differential is ideal - it has its drawbacks. For example, work here is carried out at the expense of fluid pressure, resulting in a loss of energy, and, accordingly, fuel consumption is increased. Also do not forget that this mechanism is very sensitive to high loads, so that with each strong towage its efficiency will fall. And, of course, the oil for the LSD-differential, which was discussed above, should be of high quality, since viscous coupling has an increased sensitivity to the seals.

However, there is another kind of differentials, sensitive to the difference in speeds - they work on the basis of a hern pump. This is a relatively recent technology - more precisely, it began to develop along with computer progress, as the driver can drive a hertronic pump alone in modern cars. It is expected that in the near future this type will become the most popular - it is installed, for example, on all Toyota cars. But do not forget that you now need to carefully choose the oil for LSD. The differential between Toyota and other brands that use this technology is sensitive to it.

Differentials sensitive to the difference in the transmission of torque

Well, the second type, as you already know, is sensitive not to the difference in speed, but to the transfer of torque. Naturally, the design of this mechanism is strikingly different - most often in the market there are mechanical worm-type differentials. The principle of their work is to ensure automatic locking in the event that the difference in torque between the body and the drive shaft exceeds the permissible norm. As a result, if this difference rises to unacceptable values, then an automatic redistribution of the torque occurs.

It is worth paying attention to the fact that the blockage is not complete, that is, it depends on what is the difference between the torque of the body and the drive shaft. Often, this is the rear differential LSD - this means that it is not installed on the front, but on the rear axle of the car.

You can meet the two most popular subspecies of this mechanism - a torsion and a kvayf. The first was formed directly from two English words, torque and sensing, which are translated as "torque" and "sensitive" respectively.

Well, now you know almost everything you need to know about such a mechanism as the differential LSD. Toyota, BMW, Mercedes and all the leading brands of cars are almost always equipped with such devices, because at the moment they are the most effective.