What is a sequential gearbox. Sequential gearbox: classification and principle of operation. Sequential gearbox: how it works

When creating a sequential gearbox, the developers set a goal to reduce the interval between speed changes. Thanks to the design features of this transmission, this is achieved by simplifying shifting and no clutch pedal operations.

This is especially important for beginners and inexperienced drivers who have difficulty in correctly following the switching procedures. But professionals will also appreciate the checkpoint, thanks to its convenience and the ability to subtly feel and control the behavior of the car, using the maximum of its capabilities.

The principle of operation of the checkpoint, as mentioned earlier, is sequential switching, that is, the driver cannot "jump" from 5 to 2 gears, he needs to go through each one in turn. Constructive sequential gearbox is a somewhat modernized "mechanics" equipped with an electronic unit and a hydraulic mechanism (or electric servos).

Sectional sequential checkpoint:

It should be mentioned that engineers have also developed a so-called cam gearbox, which is structurally similar to a mechanical one. Differences from the usual "mechanics" - in the device of the gearbox clutch: instead of a crown with small teeth, it has several large cams (up to 7 pieces), engaging with similar cams on the gear. Such boxes are equipped with two switching mechanisms:

search - the usual option, when you can arbitrarily turn on any transmission;
sequential control system.

Cam-type gearboxes are used mostly in sports cars and race-ready cars due to their high speed and precise shifting. For everyday driving, its advantages are offset by high cost, demanding consumables and rapid wear. In addition, the absence of synchronizers requires very precise actions from the driver, and good skill is required for "city" driving at such a checkpoint.

What is Sequential Box

A sequential gearbox on a car means that the driver selects gears not randomly, but in a clear sequence, moving the gearbox selector in one of the directions. This is the difference between this box and "mechanics", where after squeezing the clutch, the lever can be moved to any of the positions.

Such a checkpoint is a relatively new invention that appeared in the early 90s of the XX century. Initially, racing cars were equipped with these units: for example, the BMW 3 Series sports cars from the motorsport division of the automaker. The choice of a sequential gearbox for equipping sports cars is dictated by the test results: studies have shown that a driver with the help of such a gearbox can better control the car, in comparison with a classic automatic transmission, while he still has the opportunity to influence the process of changing gears as effectively as on " mechanics ". This advantage of the sequential unit is especially manifested where it is necessary to change the driving speed sequentially.

The new box found the love of car owners, although some complained about some "slowness" of gearshift gear shifting. But the second generation of sequential boxes solved this problem too.

Shift Lever Appearance:

Shifting "up" increases the gear, "down" - lowers. Some vehicles may also be equipped with steering wheel switches for driver convenience. The role of the clutch pedal is performed by a hydraulic mechanism under control, the latter also takes over the shift, if the gearbox operates in the "full" automatic transmission mode.

How it works

We all know what an automatic or adaptive and manual transmission is. In the first case, the system does everything by itself, relying on the current loads and the speed of the machine. That is, it adapts to the car. In the case of mechanics, you need to change gears yourself.

In the case of a sequential gearbox, it is important to note that it is distinguished by the ability to change gears sequentially. Roughly speaking, if on mechanics you can "jump" from 5 to 3 speed, then the sequencer will not allow you to do this

There is a switching sequence that the SKPP cannot break.

Initially, SKPPs were created for racing cars, Formula 1 cars and cars that take part in professional races. But automakers liked the idea, which is why many are introducing such boxes into civilian cars. And it pleases.

The mistake of many is that they consider the SKPP to be an analogue of the automatic transmission. In fact, mechanics served as the inspiration for the creation of the sequencer. It was built on the basis of a manual transmission.

Let's consider the principle of operation of this device and the key features of the SKPP. So you will understand what it is and how the whole sequencer system works.

The SKPP does not have a clutch pedal. This is a pleasure for those who do not have a lot of driving experience. Management is simplified, you do not need to constantly squeeze the clutch. The electronics are responsible for it, receiving signals from the sensors when reading the accelerator pedal presses and engaging the gear. The box, having received a command from the control unit, transmits a signal about the speed at which the car is now moving by sensors. The progressive block is the last stage where the motion parameters are adjusted. He studies literally everything from engine speed to air conditioning on or off.
In the design of the sequencer, spur gears are used. Their efficiency is higher in comparison with helical structures, standing on the mechanics. The latter have impressive frictional losses. Although spur teeth transmit less torque. To compensate for this, the gears are set to a large size.
Hydraulic servo drive. The last distinctive feature. Such a device switches between speeds. Now many are sure that the hydraulic servo is the property of robotic boxes. A common mistake because they use electrical devices.

The sequencer works very simply. You can use the gearshift lever or paddle shifters directly. This is a technology borrowed from racing cars, which has taken root very well among the people. Especially at BMW and Toyota.

If you look at the box, you will see a lever on it that moves up and down. Plus there are additional modes, depending on the automaker.

Pressing up (where there is +) raises one gear up, and moving to the side with "minus" allows you to lower the box by 1 gear.

This is what comfortable and convenient means. It is not surprising that many people strive to put the SKPP on their car. Some craftsmen manage to cram the box onto the VAZ 2108 and 2107. There are also factory models paired with a sequential one.

But I'll be honest. This is true for sports cars, from which you expect speed and minimal losses during acceleration. For a car with less than 150-200 under the hood Horse power, and which serve for family trips, there is no need for the UPC.

Traditional box

On traditional gearboxes installed on most domestic cars, the neutral position of the gearshift lever is set in the middle. To get under way, we squeeze the clutch and engage first gear. In the future, with a rise in speed, it is recommended to switch them sequentially.

These gearboxes are much less likely to fail in unexpected overload situations. By using grease for lubrication instead of oil lubrication, the likelihood of loss of lubricant through the shaft seals is reduced. The reduced likelihood of loss of lubrication is especially important for vertically mounted gearboxes as well as agitators.

In the picture above, the center gray colored shaft is the input shaft. The same shaft is shown in the figure below. It is designed with an eccentric cam at the end of the shaft. The cam is located inside the center of the cycloidal disc. As it rotates, the cam moves the cycloid disk in a circular orbit. External fixed pins and rollers hold the disc and cause it to roll inside a ring of fixed pins. When the disc rolls move the inner set of pins and rollers attached to the output shaft.

However, nothing prevents us from starting immediately at the second speed, if the road condition is normal and the engine is designed for such an action. Trying to start the engine with a dead battery, while pushing the car, we can turn on the third and even the fourth at once for relief. Nothing prevents this. Reducing the speed to perform a maneuver, we slow down, from the fourth gear we go directly to the second or to the first. Confused, you can turn on the wrong speed on the go, which is far from harmless for a car.

One turn of the cam moves the cycloid disc over one outer pin. As the disc rotates, the inner pins are forced along with it at the speed of the disc. This means that there is a reduction in gear and the output rotates at a lower RPM than the input shaft.

The nature of the design makes them much smaller in size than a conventional gear reducer for the same transmission ratio. This means you need less space to mount them. They weigh less and are lighter in terms of installation and repair personnel. Smaller internals and sliding action of rotating components make the gearbox quieter than conventional gearboxes.

Sequential gearbox

The evolution of the manual transmission led to the invention of a number of types of transmissions that, to one degree or another, made it easier for the driver to drive. An important step in this regard was the invention of the automatic transmission, which was subsequently transformed and improved, allowing the driver not to think at all about when and how to switch to the desired gear. But the mechanical transmission did not go unnoticed by the engineers - it was also constantly modernized and modified, inventing more and more gear shifting mechanisms. One of the results of such research was a sequential gearbox - a transmission, characterized in that its gears can only be switched on in a strict sequence: up to increase the gear, down to decrease.

How sequential transmission works

This type of gearbox is built on the basis of a conventional manual transmission. Its main difference is that instead of helical gears there are spur gears, there is no clutch pedal (this role is played by the electronic control unit), and the gears in this box are switched using a hydraulic mechanism

This significantly (up to 150 milliseconds) reduces the shift speed, which is most important for sports cars, on which, by the way, the sequential gearbox is installed most often. So, it is the sequential gearbox that is mounted on racing cars participating in Formula 1 and other similar competitions.

The designers realized that a gearbox with such a mechanism would be the most convenient for the rider, because when driving at high speed, when the car is subject to vibration, it is quite difficult to get into the desired gear. And the sequential gearbox copes with this task for five plus.

However, for more than a dozen years, the sequential gear shifting mechanism has been used on "civilian" cars. In everyday life, it is called the "manual" mode and it is typical for automatic transmissions.

Pros and cons of sequential gearbox

As with any mechanism that operates under load, the sequential transmission has its own characteristics.

On the positive side of this unit is the lack of a clutch pedal, which is important for novice drivers (if we are talking about using this type of transmission on production vehicles). The second positive factor of a selective gearbox is considered to be the gear shift speed, which is higher than that of classic automatic and manual transmissions.

The third advantage of this transmission is its economy - thanks to the shortened gear change times. The fourth aspect is the choice of two modes of gear shifting (automatic or mechanical). Such a box is characterized by the presence of paddle shifters by means of which the driver changes gears without taking his hands off the steering wheel.

This box also has its drawbacks, and they lie in the design of the unit itself. The fact is that the hydraulic mechanism of the sequential gearbox is unstable to wear and when driving under heavy load is prone to frequent breakdowns. On sports cars, where the loads are very high, such a box is often sorted out after every second race. Sequential gearboxes used on production cars (BMW M3, M5, Mercedes-Benz C-Class) are characterized by a higher power resource due to the fact that they do not experience overload, like racing cars

And yet, if you operate the sequential gearbox incorrectly (in manual mode, it is important to feel the moment and switch gears on time), then it will not last long on a production car either - the hydraulic clutch drive and other components and assemblies of this transmission may fail. And repairing a sequential gearbox is not a cheap pleasure.

Automatic transmission

To make driving easier, was invented automatic transmission gears, which freed the driver from the need to choose the driving mode on a particular section of the path. The machine switches itself, while the driver, working with one foot, either adds speed or slows down. Driving a car with an automatic transmission requires less qualifications, and it is not for nothing that the permit to operate such a vehicle has now been singled out in a separate category.

They are ideal where shock loads are expected because all parts are in compression rather than tension as is the case with traditional gear teeth. Their reliability and durability are outstanding! Disclaimer: Since the authors, publishers and resellers are not aware of the context in which the information provided in this article should be used, they are not responsible for the consequences of using the information contained or implied in any articles.

If you have any recommendations for maintenance equipment maintenance, in particular the elimination of defects and the prevention of equipment and equipment failure, or successful improvements have been made to the reliability of the equipment, please feel free to send me your articles for publication on this website.

But work on improving the mechanical transmission did not stop. As a result, a sequential transmission appeared, which also does not provide for the presence of a clutch pedal, but works on different principles. And its main feature is strictly sequential gear shifting.

Get the ultimate worldwide reliability for your company

You can contact me by email. Now give your company a reliable system to ensure the reliability of world-class operational assets, minimum maintenance costs, and maximum operating profit. Most of these blocks can be easily replaced with the correct interface pieces. The main variations in the rear housing, rear clutch and third control shaft are consistent with each other, as well as some changes in the external configuration of the bell.

The principle of sequencing

Sequential gear changes can be noted, for example, on motorcycles where they are engaged with the foot. The neutral position is there most often between the first and second gear. The same mechanics apply to tractors and large trucks. Sequential switching is most widespread in sports car boxes, where every millisecond is dear and the speed reduction when switching is unacceptable. The use of hydraulics allows this process to be further accelerated and reduced to a minimum.

Low start position, 1 "10 spline input shaft, 1" 10 spline output shaft, external rear seal. On the right side of the main body, on the underside, there are two threaded holes, which are closed with threaded plugs. In other applications, these holes can hold greasy caps that carry the lateral shafts for the side rewind mechanism.

Also notice the small reinforcing rib added on the bottom of the rear case at the rear attachment point. Internally, the main shaft is slightly larger aft of the main body using a different "spacer", speedometer drive device and lock nut

This minor change is not often reflected in current parts catalogs. For interchangeability, the rear housing can only be replaced with a corresponding change to the main shaft.

The sequential mechanism is based on a conventional manual transmission, somewhat complicated in the process of modernization.
The main feature is that with its help it is possible to switch from low to high gear without reducing the vehicle speed, which invariably occurs during the operation of a traditional gearbox.

To use the senior starter position in earlier vehicles, you need to install the later section of the front tunnel and the bulkhead panel of the frame. There are additional reinforcing ribs on the outside of the bell to reduce vibration and noise, as well as a thicker front flange on the top for mounting bolts. There is also a rubber shaft seal on the gearbox housing cover, which is interchangeable and often retrofitted with older units.

Unlike the helical gears on a traditional car gearbox, the cam gears are spur and long. This makes it similar to the transmission of a sequential box. And it is this feature that allows both systems to switch without reducing speed. At the same time, the device of the box itself is simpler - there are no synchronizers, and instead of many small teeth on the gear and coupling, there are end protrusions. These are the same cams that directly engage with the gap.

There are also some indications that the front seal cover may have been manufactured earlier. The low position put the starter motor very close to the bottom flange on the engine block. The high position put the starter motor very close to the distributor housing.

Please refer to the technical equipment of the propeller shaft for variations of the three different propeller shafts used to accommodate these different gearboxes. Combining a method of movement between a more comfortable manual system and a more controlled automatic, simply raising or lowering the lever, or, in more modern models, pressing the cams.

Design features

The sequential transmission is essentially the middle link between manual and automatic transmissions. This is really so, because, in fact, on the one hand, the driver does not think about which gear is currently on. On the other hand, the moment of switching is still selected manually, therefore, such a mechanism cannot be called fully automatic.

The shafts have a set of gears different sizes, and these gears can be connected to each other in various combinations by changing ratio... The spring mechanism of the gearbox is triggered when the gear is shifted, and the shafts jump to the next position and vice versa. This is how the sequential mechanism functions, which, in fact, does not include any automation and electronics.

Sequential box advantages and disadvantages

The features of the sequential box and its design lead to obvious advantages:

Ease of shifting and high speed of gear changes.

ECUs and hydraulics reduce shift times to 150ms, which is critical for professional riders. No one, even the most advanced, classic manual transmission or automatic transmission can achieve such a result.

In addition to speed, the sequential box eliminates the "miss" past the desired gear, because the transition between them is carried out strictly sequentially.

Machine speed is not lost when shifting.

When working with "mechanics" when changing gears, the speed decreases slightly. This is relevant for turbocharged engines that have time to fall into a turbo lag while the driver is manipulating the transmission.

The economy of the car.
Convenience of control thanks to the possibility of using paddle shifters.
Selectable mode - manual and fully automatic switching.

This is true for sequential gearboxes that can operate in automatic transmission mode. But this design option is not used everywhere, a sequential transmission is not necessarily combined with an automatic.

There are also disadvantages of a sequential checkpoint:

Increased susceptibility to wear and stress.
The units are very sensitive to operating conditions.
The high cost of the box and its maintenance.
Gearbox parts are quite expensive, and repairing it will also cost an impressive amount.

Strengths and weaknesses of cam gearboxes

A number of high-speed cars have a cam gearbox. The advantage of this type of box is that it allows the machine to achieve high speed performance. The components of this gearbox allow to withstand high loads. Due to the fact that there are spur gears, an increased efficiency is noted, to a lesser extent, axial loads are created on the shafts of the cam gearbox. The gearshift mechanism for this gearbox is sequential (sequential). The change of speeds occurs as a result of the implementation of the shift of the lever forward or backward. As a rule, cam gearboxes do not have synchronizers, which increased the speed of the gearbox.

During movement, gear shifting is carried out without squeezing the clutch, it is enough to slightly release the accelerator pedal. When changing gears, rpm power plant do not fall, as a result, acceleration occurs faster.

However, the cam box has several disadvantages:

relatively small working resource;
high price;
from an economic point of view, the direct installation of the box on the car in place of the existing one (automatic transmission or manual transmission) is not a profitable solution.

Thus, sequential automatic transmissions can be found on racing cars, motorcycles. This checkpoint is typical not only for cars, but also for heavy vehicles. The speeds can be switched by means of paddle shifters, which is an advantage of the gearbox. Ease of operation is an additional aspect why you can opt for a car with this gearbox.

Advantages and disadvantages

Now you know what SKPP is and what sequencing means. No? Yes, this is the same sequence in translation. Here, in general, everything falls into place.

After watching the video and studying the features of such a box, the question arises - is it worth taking the car from this checkpoint. I will help you a little by telling you about the strong and weak sides sequencer.

Let's start with the benefits.

High switching speed. The automaton lives its own life, therefore sometimes it openly dulls and does not do what you expect. The mechanics are more difficult to switch. The optimal speed is given by the SKPP. Electronic unit and hydraulics ensure minimal time-consuming transition from gear to gear

This is extremely important for professional motorsport.
Convenience. Squeezing the clutch pedal, getting into gear, and even at speed with a bad road is a dubious pleasure

The SKPP guarantees precision and comfort when shifting. This is an indisputable fact.

No loss of speed. Yes, the sequential gearbox switches quickly, there are no gaps between the transitions, hence the measured ride, a quick set of speed.
Fuel consumption. All the previous points affect the appearance of this advantage. The SKPP uses fuel sparingly and helps to save money.
Paddle shifters. An additional option that makes you feel like a racer. Convenient and unusual.
Two modes. But here I will make an amendment. This automatic transmission has the function of switching to manual mode using a sequential system. So this is rather a plus of the machines.

But not everything is perfect. The SKPP has two significant drawbacks.

Low resistance to stress and wear. The system is complex, consists of many elements and requires careful handling. You can't just flick petals or a lever at random. It is necessary to choose the right moment for switching. If this is not done, the mechanisms will quickly fail. It is not for nothing that the SKPP are on the cars of professional racers.
Price. It is high for the car itself with the SKPP and for the maintenance of such a box. Although, if you have the money to buy a sequential car, the cost of repairing it shouldn't be an issue.

Minuses

But this box also has its drawbacks. The hydraulic mechanism is subject to significant wear due to the heavy load during operation. On cars participating in races, mechanics repair the box after the second race. In production cars, a much greater durability resource is laid.

When used, they do not experience the same stress as sports cars. Therefore, at correct operation the service life of a sequential box is not less than that of a mechanical or automatic box. But if you operate such a box without thinking about the consequences, then premature failure is guaranteed to you

It will be a hydraulic clutch drive, another unit or unit, it is not so important. The main thing to remember is that repairing a sequential box is very expensive.

Nowadays, sequential transmission is attracting more and more car owners. It is installed on many new models of cars and even motorcycles. The technology of this transmission is being improved and brought to ideals. The time is not far off when not only sports cars that are equipped with a sequential gearbox, and even a cam gearbox, will use a convenient transmission, but many car owners will also be able to appreciate the advantage of sequential gear shifting.

The car's gearbox is one of the most advanced vehicle components.

During the production of cars, fundamentally new gear shifting systems with different mechanisms were developed. One of these devices is a sequential checkpoint.

Sequential gearbox: what is it

The concept "sequential" comes from the English word sequence which means "sequence". Gears in such a box are switched sequentially, from lowest to highest, and vice versa. This shifting principle is used in motorcycles where foot control is used. Indeed, it is difficult to perform complex manipulations when controlling gear changes with the foot. Therefore, we chose a simple algorithm: moving the lever up corresponds to an increase in the gear, down - to a transition to a lower gear.

Video - clearly shows how quickly the gear changes on the sequential gearbox:

There are also some vehicles where a sequential checkpoint is traditionally used, military equipment (self-propelled artillery vehicles, tanks). They have their own specifics. First, they are driven by unskilled drivers. Secondly, there is a fast transition to an upshift with minimal "dips" in power during the shift. The second quality (the practical absence of dips in power and speed) determines the use of sequential transmission in high-speed sports cars.

Video - what does a sequential gearbox mean on a racing Peugeot car 208:

The principle of operation of the sequential gearbox

The design of the sequential gearbox in appearance differs little from the traditional manual gearbox.

If you take a closer look at the gear mechanism, you can immediately notice that the teeth are located strictly perpendicular to the side surface of the gear.

This is necessary to ensure that they move in a straight line during switching.

On the one hand, straight-toothed gears have less friction than skew-toothed gears due to the complete conformity of the surfaces. On the other hand, the helical gears in the manual transmission are designed to increase the torque that the gear train can handle. Therefore, gears of increased width are installed in many sequential boxes. This increases the design of the teeth and their strength.

The design of the sequential gearbox makes it quite easy to organize automatic mode switching. There are the following sequential checkpoints:

with the usual mechanical system gear shifting;
with a sports shifting system;
with an automated switching system.

Hydraulics are used to increase the switching speed. With the help of hydraulic servo drives, switching times are minimal. During the activation of the shift to another gear, the accumulator is filled, which contributes to the creation of pressure in the hydraulic system. The gear change time is a tenth of a second. This decisive fact determines the use of sequential gearboxes in sports cars. Often, the gearbox controls are placed in the steering column area, which further simplifies the control of the modes.

How does it differ from robotic

Many car enthusiasts mistakenly believe that the sequential gearbox is a close relative of the robotic one. Their fundamental difference lies in the use of a hydraulic system in a sequential box when shifting gears. The robotic box uses an electric drive for this. also in robotic boxes a different gear shifting mode is applied.

Video - gear shifting on a racing car's sequential gearbox:

Their advantages and disadvantages

The main advantages of such boxes:

minimum time for speed switching;
minimum power losses of spur gears;
fuel economy;
the ability to switch from manual to automatic mode;
the ability to control the shift from the steering column;
use of the system without using the clutch pedal.

Disadvantages of sequential checkpoint:

sequential gear shifting sometimes constrains the driver in terms of applying extreme driving styles, necessary gear changes, for example, when starting the engine "from the pusher";
relatively high weight of the gearbox with the same power;
reduced service life associated with the technical complexity of the mechanisms;
high cost of maintenance and repair.

In which passenger cars can you find a sequential gearbox

Of the most common passenger cars an example of a 1996 BMW with an SMG gearbox. The SMG1 and SMG2 systems were installed on the BMW 3 Series with the S index. Since 2004, this transmission has been installed on the BMW E60 M5. Also, a sequential gearbox was installed on certain models of Toyota Corolla, Mercedes S-class, BMW X5 cars.

The layout of the sequential gearbox and its elements is shown in the figure:

In the figure: 1 - sequential gearbox control unit, 4 and 5 - indicator and mode switch, 7 - 6 stepped gearbox, 12 - hydraulic block, 10 - hydraulic drive, 11 - clutch.

Features of installing a sequential gearbox on VAZ cars

Many motorists purchase sequential gearboxes with a cam mechanism as an upgrade to their VAZ. Their appearance something like that.

As for the significant effect, it is not necessary to count on this, since the dynamics of the car at the same time, judging by the feedback from the owners, increases slightly, although these boxes are called "sports". In addition, the weight of such boxes is usually higher than traditional ones. There, wide massive gears with a perpendicular arrangement of teeth are used to compensate for their low load capacity.

In addition, the spur teeth increase the noise level of the gearbox. The actual service life of a handicraft sequential gearbox is short. Such a gearbox can be installed if the car is supposed to take part in sports competitions, but not for everyday city driving.

conclusions

Summing up, it can be noted that the development and introduction into serial production of sequential gearboxes made a certain technical progress in the development of the automotive industry. Such checkpoints were not widely used due to the presence of numerous shortcomings.

Read about and what it affects.

Thickness gages for car body paintwork and have different principles of operation.

Automotive engineering has made great strides during its existence. Powertrain innovation is proof of this. On cars that exist today, you can find gearboxes of various types. An example of such a mechanism is a sequential gearbox.

What is a sequential gearbox

New transmission technology became widespread in the 1990s. Such a gearbox is a gearbox that allows you to change speeds only in a sequential way. It differs from the usual version known to all in the mechanism of operation. Sequential switching was provided for those cases where the action on the control system is carried out with the help of the foot, as, for example, on motorcycles. The sequential gearbox is also relevant in cases with sports cars, when fast gear shifting is required. Application was also found in the case of a vehicle with a large number of gears. In this situation, traditional movement is inconvenient. This is typical for trucks and tractors.

Often these boxes have a mechanical type of work. But with the passage of time and the development of technology, the automatic sequential transmission is becoming more common. The difference from the conventional version is that there is an opportunity to choose between manual and automatic mode of gear shifting. Whichever type of work is used, the main feature is a strict sequence in switching. Down or up only. The driver either increases the speed or decreases it. Such an approach in the system of the mechanism makes the driving process easier for the driver and increases the speed of the transition from one speed to another. It is for this reason that the automatic adaptive sequential system has gained popularity among many car enthusiasts. Simplicity and convenience are two main components that complement each other.

How the sequential gearbox works

The basis for the sequential gearbox is the same familiar manual transmission. Only in this case, it was improved: the design uses straight teeth of gears, instead of the common helical teeth. It is also based on a servo drive built on a hydraulic system. It is thanks to this that the speeds change quickly. You can schematically depict a box of this type as follows:

Attention! The sequential gearbox does not allow the driver to select gears independently, that is, to jump from one gear to another immediately after several.

Some motorists have a separate question about the sequential automatic transmission, namely, what it is. The answer is on the surface: it is an automatic transmission equipped only with sequential gear changes (i.e. sequential). A significant difference of this type is the absence of a clutch pedal in the car and the way of switching the speed (only down and up).

Dealing with the question of the device of these structures, it is worth mentioning about the cam sequential gearbox. In terms of design, both options have similar characteristics. For example, both variants have both spur and long gears. They affect the speed of shifting from one gear to another. Determining which of these checkpoints is better is very difficult. Therefore, experts in this field have combined these two mechanisms into one.

The principle of operation of the sequential gearbox

As mentioned earlier, a sequential gearbox is characterized by the absence of a third pedal - the clutch. This feature is especially relevant for those drivers who have little experience in handling transport on the road. After all, the constant distraction of the left foot on the clutch pedal is a problem for many. But this does not mean that this mechanism is absent in the gearbox. It exists, it only works differently. Consequently, the operation of the sequential checkpoint itself is different. The clutch is controlled by a special electronic unit, which, in turn, receives the necessary signals from the sensors. They determine the force of pressure on the gas pedal from the driver's side and control the inclusion of a specific speed. The gearbox receives a signal from the electronic unit, which in turn, using sensors, transmits all the necessary information about the speed used to the progressive unit. It is here that the last process takes place - adjusting the speed limit based on the following indicators:

the number of engine revolutions;
air conditioner operation;
the force of pressing the pedal, as well as a number of others.

The next principle of operation of sequential gear shifting is the used spur gears. If we compare them with the helical teeth, which are used in manual transmissions, they give out a higher efficiency. This is due to the fact that the first of them leave large losses during friction.

And the third feature of the operation of the sequential gearbox device is characterized by the presence of a hydraulic servo drive. Thanks to him, there is a quick change from one gear to another.

Important! Hydraulic servos and robotic transmissions are not the same thing. The differences lie in the device design: the latter uses an electric servo drive.

More detailed and visual information on how a sequential gearbox works can be obtained from the following video:

Which cars are equipped with a sequential gearbox

The sequential gearbox is most widely used for sports cars participating in races. For example, such a system of work is used in Formula 1 cars. Among the transport models on which this type of checkpoint is initially used, the following stand out:

BMW M3;
BMW M5;
Mercedes Benz C-Class.

But the sequential box is much more common than meets the eye. As mentioned earlier, this type of device can be found on agricultural transport and on heavy vehicles... In the design of machines with a sequential gearbox, in this case, it became even more widespread.

Every driver wants to provide his car with everything necessary for a comfortable and safe ride. So some motorists install a gearbox with sequential gear shifting on their cars, specifically replacing the old transmission with a new one. Therefore, the device can be found in completely different vehicles. Very often, a sequential gearbox is installed on a VAZ. This provides the driver with an easier driving experience. In this case, preference is given to the cam system. Thus, this transmission can be installed on any car, the main thing is to choose the right model that is suitable in all respects. There are a large number of options for a sequential gearbox on a VAZ. Therefore, there will be no problems in choosing or finding the right device. Moreover, some offer an individual assembly for the car by high-level specialists.

Pros and cons of sequential transmission

In order to figure out what to expect from a transmission, you need to consider its positive and negative aspects. Among the pluses, the following points should be noted:

High speed and ease of gear shifting. Thanks to the electronic unit and hydraulic mechanism, the speed of transition from one speed to another is minimized. No other gearbox can boast of such indicators: neither mechanical nor automatic. Well, the main thing is that with the use of a sequential transmission, the driver does not have to frantically try to find the gear he needs at the moment. This is especially true when passing sharp turns or driving on a ring, when it is difficult to keep the car on the correct trajectory.
There is no loss of speed when shifting. This feature is loved in the circles of racers, and, of course, ordinary drivers also highly appreciated the presence of such an opportunity in the transmission.
Thanks to the well-thought-out design of the sequential gearbox, fuel is consumed economically.
Gear shifting with paddle shifters. This technology further simplifies driving while driving.
Possibility to choose between automatic and manual gearshift modes. Of course, sequential transmission can exist separately from this function. But if, nevertheless, it is used, then this definitely refers to the pluses.
The clutch pedal is missing. This is especially true for novice drivers who, due to their little experience, find it difficult to cope with a manual transmission.
When shifting the lever, you do not have to think about which gear to choose. The driver simply either slows down or increases the speed.

Cons of sequential transmission:

Sensitive to high loads and wear. We are talking not only about sports cars, but also simple civilian cars.
Attention! As simple as it is to switch gears at the checkpoint, it is important to do it in a timely manner. If you neglect this point, then the system will quickly become unusable.
High maintenance cost. The principle of the sequential box is a complex mechanism. The more complex the mechanism, the more expensive its maintenance.
It is possible to achieve an increase in the power of the car by installing a sequential gearbox only if you switch from higher gears to lower gears and vice versa in time. So the driver must feel good about his car, which is not always an easy task.

Conclusion

The sequential gearbox has given motorists new opportunities. The device and the principle of operation deserve attention from drivers, and the convenience of use is gaining more and more consumers. Thanks to all of the above, the checkpoint of this type is becoming more widespread every year. And considering everything positive sides gearbox, it's not casual.

But the non-trivial shift mechanism inherent in this type of transmission forced the designers to look for alternative ways to shift gears.

And their efforts were not in vain - the gearbox family was replenished first with automatic boxes, and then with other varieties - robotic, variable, sequential.

But it just so happened that an ordinary car enthusiast can speak with confidence only about mechanics and an automatic machine. A much smaller number of motorists know what a CVT or a robotic transmission is. And there are very few people who know how the sequential box is arranged and works. We decided to fill this gap in automotive education.

What is a sequential checkpoint

The classic manual transmission, despite some shortcomings, continues to dominate the automotive transmission segment. There is an objective explanation for this - mastering the switching skills is quite simple, you just need a little practice. But the main thing is that such a checkpoint provides the driver with freedom of action: moving at the desired speed, he can switch to any gear without restrictions. For example, having accelerated, switch from third to fifth immediately, move off from second and even third, if there is a sufficient slope, brake sharply and turn on the second gear after fourth.

Of course, this cannot be called complete freedom - the selected gear must correspond to the load on the car and the speed of movement.

The sequential checkpoint does not allow this. Its main difference from mechanics is the need for sequential engagement of all gears, regardless of direction.

You ask, what's the point in such a transmission? The answer is very simple: to make driving easier. There is no contradiction in this - cars with a sequential gearbox do not have a clutch, so the driver does not need to think at all about which gear is currently engaged, and which one needs to be switched on when picking up speed or, conversely, when braking. As a result, the gear shifting process is noticeably accelerated, which can be called the main advantage of the gearbox.

Strictly speaking, gearboxes of this type are an integral part of motor vehicles, especially of older generations, where shifting is carried out with a foot pedal. But even today, for example, BMW motorcycles are equipped with this type of transmission, which also evolves over time, becoming more perfect, trouble-free and comfortable. So, at present, seven-speed sequential gearboxes of the SMG model are produced. The first generation of such gearboxes was installed on BMW cars E36 M3 since 1996, since 2001 SMG 2 became the main transmission of the E46 M3, and the third generation was included in the E60 M5.

If, when using a manual transmission, an experienced and skilled driver takes about 0.6 seconds to change gears (the average statistic is noticeably higher), then the use of modern sequential gearboxes can reduce this time interval by about three times, to 0.2 seconds.

Of course, for an ordinary motorist this is uncritical, but for athletes such a gain in time is very significant, given that during the race you have to switch very often.

It should be considered a misconception that the SKPP is more complex than mechanics. Automatic transmission - yes, it is indeed a very complex device, but the design of the SMG-type transmission is simpler than that of the manual transmission. If only because there is no synchronizer here, we will talk about the construction of sequential boxes a little later.

Thus, the correct answer to the question of what a sequential gearbox means is as follows: this is a type of transmission in which the gears are switched exclusively sequentially (1-2-3-4, etc.), both up and down, but but much faster, while the clutch pedal is absent, and its role is played by the electronics. At least in passenger cars.

Device, features, principle of operation of the SKPP

O main feature sequential transmission, you already know - this is the impossibility of shifting gears in an arbitrary order (or rather, the lack of free choice). But what is the point of such a box? The fact is that the driver does not always have the ability to engage the desired gear by braking (when changing from higher to lower gear) of the car. Especially in cases where the number of gears is large (from six and more), which is typical for agricultural machinery, tractors, heavy vehicles.

Since the clutch pedal (but not the clutch itself) is missing, this theoretically simplifies handling vehicle- there is no need to synchronize the movements of the left and right legs when switching speeds. The clutch is controlled by receiving all the information necessary for this from sensors and sensors that monitor the degree of pressing the accelerator pedal and attempts to engage a certain gear. The ECU, analyzing this data, sends a corresponding signal to the executive device - the progressive block of the SKPP, which corrects the vehicle speed.

To have an idea of how a sequential gearbox works, you also need to know that, unlike a mechanical analogue, instead of bevel gears, spur gears are used. Such a mechanism has a higher efficiency due to the reduction of friction losses, however, this reduces the torque. This disadvantage is compensated for by installing gears of a larger diameter. Note that the noise level during transmission with spur gears is much higher.

Finally, another feature of the sequential gearbox is the use of hydraulic servo drives, the function of which is to facilitate and speed up switching between speeds. True, servos are also used in robotic boxes, but there instead of hydraulics, an electric drive is used.

If on motorcycles, gear shifting is carried out with a pedal, then in cars - with the usual lever or buttons (which are even more convenient to use, although this is a matter of habit). The location of the lever is either standard, on the center console, or on the steering wheel, which is typical for "Americans" and "Japanese". Such a box is designated by the letter "S" (from the word

Sequence, which is translated from English as "sequence", "sequential").

In some variations of the sequential box, gear shifting can occur in automatic mode. Typically, such SKPPs can operate in three modes:

standard mechanical, with manual gear shifting;
sporty mechanical, allowing to speed up the shifting process;
automatic, relieving the driver of the need to change gears (yes, there are analogies here with an automatic transmission, but there are many differences).

The principle of operation of the sequential gearbox is based on the use, which has been modernized by equipping with gears with straight teeth. Due to the presence of a hydraulic mechanism of servo drives, the driver does not require high precision when changing the mode of movement of the vehicle, which further simplifies driving. All he needs to care about is to monitor the load on power unit, making sequential shifts during acceleration and deceleration without using the clutch pedal.

How is a noticeable reduction in gear shifting time achieved? The fact. that on a manual gearbox, when the lever is moved from one position to another, the thrust of the drive mechanism is first pulled up, then it turns, and only after that it is pressed. In the sequential box, a completely different principle is used - here two rods are switched on simultaneously, one of which is pulled up, the other is immediately pressed. In other words, when changing from the third speed to the second, at the moment of shifting, the thrust of the third gear is pulled up, and the second is pressed. As a result, the total switching time is reduced from one second (average) to 0.12 milliseconds.

Many motorists confuse sequential gearboxes with cam gearboxes. There really is a lot in common between them (spur gears of increased diameter and length, as well as the presence of end protrusions that serve as the basis for engaging with the cams), thanks to which it is possible to significantly reduce the switching time. Cam-transmission vehicles are more dynamic, but this requires a lot of experience from the driver to switch at the right time. Sequential transmissions do not have this disadvantage. It is for this reason that cam-type gearboxes are installed exclusively on sports cars, although no one forbids you to perform on a regular production car. The designers of the cars of some Formula 1 teams have combined the advantages of both types of transmissions in one device, but, of course, it is at least inappropriate to compare the driving skills of the racers of this super series with ordinary drivers.

We have already discussed at the conceptual level the main advantages of sequential boxes. It's time to discuss the benefits of this type of transmission in more detail. So, the main advantages of using such a checkpoint are as follows:

lack of a clutch pedal. It turns out that this is good not only for beginners who may have difficulty working with two feet when changing gears (situations when the brake is pressed instead of the clutch are common, and this is almost guaranteed to stop the engine). Participants in racing competitions in cars equipped with a sequential transmission get the opportunity to concentrate on the track, without being distracted by the need to coordinate the movements of their arms and legs when changing;
gear shifting is at least three times faster. Considering that the automatic transmission, which also lacks a clutch pedal, is much more thoughtful than the manual transmission, then sequential transmissions have no competitors in this regard. Shifting itself here requires the driver to move the lever up when accelerating and down when reducing the speed. It is extremely simple: we pull the handle up until we accelerate to 4-5 gears, or down to full stop... You do not need to think about which gear is on now and which one should be switched to;
the absence of a time lag when changing gears contributes to some extent to fuel economy. And although this effect is insignificant, but it has an accumulative effect - this must always be taken into account;
modern transmissions of the sequential type have already simplified vehicle control to almost a minimum by transferring the control keys to the steering wheel. But it turns out that they offer an even more efficient option - an automatic mode of operation, when the driver does not have to think about changing gears at all - the electronics and a set of sensors will do all the work for him.

The sophisticated reader will probably have a very reasonable question: if sequential boxes are so good, why have they not yet received mass distribution?

The answer is trivial: along with the undoubted advantages of this type of transmission, there are also obvious disadvantages, in most cases outweighing the advantages. Let's describe them:

low resistance to high loads, without which it is impossible to imagine the operation of the transmission. No matter how simple the switching occurs, even if there is a control gearbox, it must be done, given the appropriate speed mode - if you switch to third from a speed of 60-70 km / h, it will be a clear mockery of the box. Regardless of the type. The design features of the sequential gear shifting mechanism (in particular, the presence of a hydraulic servo drive) significantly reduce the ability of gearbox parts to withstand wear. Suffice it to say that on racing cars such transmissions become unusable literally after every stage. And this is an expensive pleasure: the cost of the SKPP is much higher than that of a mechanic. But for the sake of winning in speed, the teams participating in the races are forced to go to such expenses. This is unacceptable for a production vehicle. And although here we are talking not only about forgiving driving, but also about increasing power and reducing fuel consumption, all this is not given for nothing. The driver, as mentioned above, must switch correctly, feel his car, choose the right speed for changing from lower gear to higher and vice versa. If you have little experience, mistakes in using a sequential transmission will inevitably lead to its premature breakdown, and repairing such a box will cost you a significant amount. So you shouldn't buy a car equipped with an automatic transmission if you do not have many years of experience in driving a vehicle with an automatic transmission and manual transmission. It is worth considering the factor that it will not be easy for domestic motorists to reorganize to work on gear shifting, the gear lever of which is located not on the central tunnel, but on the paddle shifters. But these are trifles compared to the fact that even with careful use, the service life of sequential boxes is several times less than mechanical and even automatic;
such a transmission is also distinguished by the high cost of maintenance, which is also due to design features. If we talk about the cost of spare parts / consumables, then the situation here is not at all rosy. And if you think that you can repair it yourself, then you are deeply mistaken here. Moreover, if you do not live in a metropolis, then you still have to look for a car service, which will undertake the restoration of the SKPP.

Let's also talk about the main misconceptions associated with the mention of a sequential type gearbox:

many believe that robotic and sequential transmissions are synonymous. In fact, this is, of course, far from reality. Although the principle of operation of both types of boxes is really similar, there are also more than enough differences. An example is the type of servo: robotic gearbox it is electric, not hydraulically based. The robot box is equipped with a double clutch to eliminate jerks when shifting gears, the sequential analog does not need it;
there is an opinion that the automatic transmission and the SKPP always work in conjunction. It is also incorrect, although this stereotype can be explained by the growing popularity of automatic boxes equipped with sport mode... In fact, the sequential transmission does not always have an automatic mode of operation, and even more so it is a mistake to assert that these types of transmission are identical. The most striking example is racing cars;
there is also an opinion that the gearbox is an attribute only of racing cars, and certainly in combination with a cam mechanism. Yes, such a bundle is typical for motorsport, but serial cars have been produced for a long time, on which a sequential-type box is successfully operated. And without the cam mechanism - it really is a race car preserve.

Scope of sequential automatic transmission

Initially, such boxes were actually installed only on cars used in various disciplines of motorsport. However, even today this type of transmission in auto racing has no competitors, allowing gear shifting as quickly as possible and without an intermediate drop in rpm. A few tenths of a second (strictly speaking, at least half a second) is a lot where the winner from the prize-winner is often separated by hundredths of a second. Add a hydraulic shift mechanism to that and you have a really high-speed drivetrain, albeit an expensive one.

But for more than two decades, SKPPs have been installed on serial cars. The pioneer here turned out to be the carmaker BMW; currently, such a box is equipped, for example, in M3 / M5 models from BMW or Mercedes-Benz C-class. Some people confuse such a transmission with an automatic transmission, calling it a "manual" version of an automatic transmission, which is, in principle, incorrect, and we have already spoken about this. Owners of cars equipped with a sequential gearbox claim that driving a vehicle has become much easier, and it is not required to accurately enter the gear, depending on the driving mode.

Many motorcycles have sequential gearboxes, a technology that has been around for over 50 years. Typically this is a foot-operated lever that has two positions: forward and backward. The neutral is located between them.

The sequential gearbox is also installed on agricultural vehicles (tractors, tracked vehicles). Here, the shift lever is also located under the feet, like on motorcycles, but can also be installed on the handlebars.

Finally, the SKPP is equipped with many models of heavy trucks and other heavy special equipment, in which the number of gears can exceed a dozen - to manage such mechanical box it would be very difficult.

Unveiled at the end of June 2015 in Goodwood, you may have noticed the sequential gearbox, which has long been an integral part of sports and supercars. Since some karakumniks are interested in the device and features of this type of checkpoint, I will tell you about it. Sequential checkpoint differs in the possibility of only sequential switching between gears. In other words, the driver can change only one gear higher or lower than the one used, without jumping over the others, as can be done in a classic manual gearbox with a search shift principle. I propose to get acquainted with this type of gearbox in more detail and dispel a couple of misconceptions associated with sequential gearboxes.

The principle of operation of the sequential gearbox

As we have already found out, the gears of this type of transmission are shifted only one by one, in a strictly specified sequence. And since the sequential gearbox is built on the basis of a mechanical one, we will make references according to the principle of operation to the manual gearbox.

At first, the sequential gearbox is characterized by the absence of a clutch pedal, which, first of all, will please drivers who are not sophisticated by experience. This greatly facilitates driving, because constant dancing with your left foot on the clutch pedal is, frankly, an amateur's business. The clutch is not controlled by the driver, but by the electronic unit, which receives a signal from sensors that read the pressure on the gas pedal and directly engage a specific gear. As the saying goes, it's a matter of technology. When the box receives a command from the electronic unit, a new signal about the used vehicle speed is transmitted to the progressive unit using special sensors. The progressive block is the last resort where the speed mode is adjusted based on various indicators: from engine speed to the operation of the air conditioner.
Video demonstrating sequential gearbox operation. How swiftly the gear changes!

Secondly, in the sequential gearbox, spur gears are used. They give out a greater efficiency when compared with helical gears from manual transmissions. This is because the helical gears have more frictional losses. But spur gears are also capable of transmitting less torque, therefore gears are often used in sequential gearboxes. bigger size to compensate for this shortcoming.

Finally, third distinguishing feature sequential transmission is the presence of hydraulic servo drives, with the help of which there is a shift between gears. Nowadays, hydraulic servos are often associated with robotic gearboxes, but this is not the case. The latter uses electrical ones.
Evgeny Travnikov talks about one of the variants of the sequential box in his video:

Advantages and disadvantages of sequential gearbox

Now that we have an idea of the principle of operation of the mentioned transmission, let's figure out what to expect from it.

Advantages:
1. High speed and convenient switching between gears. Thanks to the electronic control unit and hydraulic mechanism, switching times are reduced to 150 milliseconds, which plays a significant role in professional motorsport. None of the classic transmissions, both mechanical and automatic, can boast faster gear changes. In addition, with the sequential gearbox, you will not frantically try to get to the desired speed, rushing with all the horsepower around the ring, when the high load and shaking with vibration interfere with keeping the car on the correct trajectory.

2. No loss of speed when switching.

3. Economical fuel consumption.
The last two points are more likely a consequence of the first, but we cannot but take this into account, giving the sequential checkpoint its due.

4. Ability to switch paddle shifters. Yes, this technology, so beloved by real racers, was discovered thanks to the sequential shifting mechanism.
By the way, gamers also love this mechanism. Some even undertake to develop such boxes themselves =)

The fifth advantage could be called the choice between two modes - automatic and manual gear shifting (the so-called sport mode). But this feature is typical for automatic gearboxes... And since the sequential transmission can exist independently, we will leave this advantage to certain types of automatic transmissions.

Disadvantages:
Here we are talking not only about the loads that the gearbox of Formula 1 cars experiences on the race track, but also about the loads that the hydraulic mechanism can experience if it is incorrectly shifted on civilian vehicles. No matter how simple it is to change gears on a sequential gearbox, it must be done in a timely manner. The units of this transmission are quite sensitive and wear out quickly due to the design features. After all, the more complex the mechanism, the more likely it is to break.

2. High cost of maintenance. Actually, here you can also refer to design features sequential checkpoint, and no further comments.

Misconceptions and myths associated with sequential checkpoint

1. Sequential gearbox and robotic gearbox are one and the same.
This is by no means the case. Despite a similar operating principle, a robotic gearbox at least uses electric servos to shift between gears. And in the sequential gearbox - hydraulic.

2. Sequential and automatic transmission are inseparable.
Another misconception caused by the widespread use of automatic transmissions paired with "sport mode". However, it is worth remembering the gearboxes used in motorsport, and everything falls into place. A sequential gearbox can exist separately from an automatic transmission.

3. The sequential mechanism is installed only on race cars and other sports cars, together with a cam box.
Undoubtedly, the duo of these two technologies gives a huge advantage on the track, but for more than a decade, a sequential gearbox has been used on production cars intended for public roads.

Application of sequential gearbox

Nowadays, the sequential mechanism is widely used and even managed to become a classic for some motorcycles and cars. For example, this type of transmission is typical for an old motorcycle. But the more popular application of this technology became famous for the models of the SMG gearbox, installed on BMW cars since 1996.

SMG 1 and SMG 2 have been installed in the BMW 3 Series for a long time.
A moment of nostalgia or how it was:

1-Upshift indicator light; 2-Gear and program indicator;

3-Control lever; 4-; 5-Drive program switch (in the center console).

Main components first generation SMG shown in the figure:

1 SMG ECU; 2 ABS ECU; 3 Gear and program indicator (in the tachometer); 4 ECU of the indicator of the engaged gear and programs
5 Drive program switch (center console); 6 Control lever position indicator (center console); 7 Six-speed SMG gearbox with adjustment unit; 8 Shift Bracket SMG; 9 Drive pump; 10 Clutch slave cylinder; 11 Clutch; 12 Hydraulic block; 13 Master cylinder reservoir; 14 DME control unit*
The SMG is now in its third generation and has been installed on the BMW E60 M5 since 2005.