In translation, sequensum means "sequence". A sequential gearbox can be considered a mechanical unit in which a separate device controls the clutch. That is, in a car equipped with the described gearbox, there will also be 2 pedals, as in a car with an “automatic”, but the gears must be switched manually (in some cases, automatic switching is also possible).
Principle of operation
When you turn on the gear yourself and press the gas pedal, special sensors inform the electronic unit, which transmits a signal to the box. It also has sensors that transmit their signal about the speed of the car to the progressive block. The latter, in turn, makes adjustments to the speed limit, coordinating the work of the gearbox mechanisms. This takes into account the number of revolutions of the engine, the operation of the air conditioner and the readings on the instrument panel.
Gear shifting is carried out by means of servo drives (actuators), which are hydraulic on the sequential box. If electric, then such a gearbox is called robotic (in practice, a gearbox with both hydraulics and electric actuators is called robotic). The command to change gear is given by the driver in manual mode or using the on-board computer.
Features of sequential gearbox operation
The principles of operation are reminiscent of an automatic transmission, however, the sequential unit is characterized by the efficiency and reliability inherent in a manual transmission. Moreover, the "robot" is much cheaper than the "machine". The main feature of the sequential box is the ability to switch from low gear to high without losing speed, which invariably drops when using a mechanical unit. On a number of modern cars, the sequential gearbox is controlled by buttons located on the steering wheel, which allows you to switch without taking your hands off the steering wheel.
Another plus for cars equipped with a "robot" is lower fuel consumption when compared with an automatic transmission. The lack of a third pedal helps beginners get up to speed quickly, while experienced drivers can choose between manual and automatic gearshifts.
The disadvantage of robotic boxes is low wear resistance, which is especially pronounced under heavy loads or an aggressive driving method. Therefore, when operating this type of gearbox in manual mode, it is important to switch from one speed to another in time (you need to feel the moment). Otherwise, breakdowns are inevitable, and repairs "
The manual transmission can be either a simple robot with one clutch, or a preselective gearbox with two clutches of the DSG type. In this article we will talk about what a sequential gearbox is.
Read in this article
SMG Box: Sequential Transmission
As you know, at the initial stage in the automotive industry, only a manual transmission was used.
However, in the future, engineers have developed other types of transmissions, with the main task being to make driving as easy as possible.
A real breakthrough was the appearance of an automatic transmission, automatic transmission, which made it possible to realize the possibility of choosing and changing gears automatically, that is, without the participation of the driver.
At the same time, the hydromechanical "automatic" did not supplant the traditional mechanics for a number of reasons, the manual transmission continued to be refined, the design was constantly improved. As a result, a sequential gearbox became one of the types of manual transmissions.
In a nutshell, such a transmission differs from analogs in that the up and down gears are included only in a certain sequence. To put it simply, the driver of a car with a so-called sequential dial switches strictly in order "up" to turn on an increased, or "down" to turn on a lower gear.
At the same time, on conventional mechanics, the driver can change gears according to the "search" principle, that is, arbitrarily. The main thing is that the gear matches the speed of movement, etc. In practice, for example, you can start off from the second and immediately switch to the fourth. The sequential checkpoint will not allow this.
The device and principle of operation of the sequential gearbox
As already mentioned, a sequential gearbox (sometimes called a selective gearbox) is based on a simple manual transmission. However, there are differences from the manual transmission.
DSG gearbox (DSG): design, principle of operation, distinctive features. Reliability, DSG resource, types of robotic DSG boxes, tips.
The traditional division of gearboxes used in cars into "automatic" and "mechanics" has long ceased to be relevant. In recent years, many other types of transmissions have appeared, the main purpose of which is to simplify the process of controlling a machine while improving its technical performance.
An example of this development is the sequential gearbox, which today is equipped with many sports cars, especially supercars. Its main feature is that the speeds in it are switched only sequentially - in other words, you cannot immediately jump from the first to the third, bypassing the second. The same rule applies when downshifting.
This principle has many features, including positive ones, which make it possible to use a sequential box on the fastest cars of our time. For a better understanding of them, you should first understand what a transmission of this type is and how it works.
This type of gearbox combines the features and advantages of mechanical and automatic gearboxes, due to which the resulting unit is characterized by ease of use and, at the same time, high precision of work. It switches gears in a strict sequence - you cannot jump over one speed. At the same time, transmissions change here in record time - the box takes about 120 milliseconds to do this. This high switching speed is ensured by the use of hydraulic servo drives.
An important feature of sequential gearboxes, which brings them closer to more familiar "automatic machines", is the absence of a clutch pedal. Moreover, there is only a pedal as a control element - the clutch itself is there, but its operation is provided by automatic equipment. This makes it much easier for beginners to drive a car equipped with such a transmission.
To transmit rotation in sequential gearboxes, gears with straight teeth are used. In comparison with helical elements, they have a much higher efficiency due to the minimal frictional forces arising during their rotation.
The principle of operation of the sequential gearbox
In principle, such a transmission is in many ways similar to conventional mechanics. However, she also has many individual characteristics:
- The SKPP does not have a clutch pedal - the clutch is controlled by electronics, which monitors the force of pressing the accelerator pedal with the help of special sensors;
- the usual lever or buttons or petal keys located on the steering wheel can be used to shift gears;
- hydraulic servos compensate for possible inaccuracies in the adjustment of the driving mode.
In general, the driver only has to switch sequentially when accelerating or decelerating. This principle greatly simplifies driving.
A significant reduction in shift times is achieved thanks to the modernized principle of the use of rods, included in the design of the gearbox:
- on conventional "mechanics", when the driver changes the position of the lever, the rod is pulled up, turned and only then pressed to engage a new gear;
- in the sequential box, the thrust of the previous gear is pulled up, and at the same time the thrust of the new speed is squeezed out.
As a result, the switching time can be reduced to 120 milliseconds. For comparison: a modern manual transmission takes about 1 second to change gears. During normal driving, such a time difference may not be felt - however, this is a significant gap in the world of auto racing. That is why sequential gearboxes are used today in Formula 1 and other high-speed championships.
At the same time, the control of such a transmission is quite simple and does not require special skills and reaction speed from the driver. This compares favorably with the cam boxes, with which the SKPP has many similarities.
Where is the sequential gearbox used?
Initially, this type of transmission was developed for the needs of motor sports - this is where it is very important to be able to quickly change gears without losing engine speed. However, since the mid-90s of the last century, such boxes began to appear on serial public cars - the Bavarian concern BMW became a pioneer in this direction.
However, for the first time, sequential gearboxes did not appear on vehicles at all - for more than 50 years they have been used on motor vehicles. On most bikes, the gear changes are sequential: pushing the lever forward increases the gear, and backward decreases it. Moreover, this principle is used on motorcycles of a very different class - both on choppers and tourers, as well as on sportbikes and enduros.
Also today, sequential type transmissions are installed on various heavy machines:
- agricultural and construction equipment;
- trucks, boxes of which often have more than a dozen speeds.
In all these cases, the principle of sequential gear shifting greatly facilitates the control of equipment - the driver does not need to spend time choosing the moment to switch and find the right speed, which is especially important for trucks.
Pros and cons of sequential gearbox
Of course, units that have such serious differences from the usual types of transmissions have their pros and cons. In particular, the advantages of sequential boxes include the following features:
- Clutch pedal missing... This is useful not only for novice drivers who often find it difficult to master the nuances of controlling three pedals at once, but also for experienced drivers.
- Switching speed... According to this indicator, the SKPP significantly surpasses the "mechanics", and she, in turn, works much faster than the brooding "machine". Thus, sequential boxes have no competitors in terms of response speed.
- Easy to switch... It doesn't matter which gear is on at the moment - you just have to move the lever in the right direction or press the corresponding button.
- Modes of operation... Many boxes of this type support several modes of operation. It can be an analogue of the usual "mechanics", a sport mode, which provides even higher speed and accuracy of switching, as well as an automatic mode in which the electronics will do everything by itself. Moreover, in this case, the same efficiency of work remains.
However, sequential transmissions are not ideal - along with significant advantages, they also have certain disadvantages. Moreover, in some situations, they can turn out to be more significant than the advantages. Here are the basic notes on these boxes:
- Fragility... They do not tolerate high loads that inevitably arise during the ride. A particularly sensitive element of such a box is the hydraulic servo drives. On average, the gearboxes are several times smaller in comparison with traditional types of gearboxes.
- Complexity of maintenance and repair... Maintenance and even more repair of a sequential transmission is costly due to the design features. It is almost impossible to eliminate any problem that has arisen here on your own. But even contacting a service station can not always solve your problem - sequential boxes are still quite rare in Russia, so finding a master who has experience with them can be very difficult.
In general, the sequential gearbox is undoubtedly one of the most promising types of transmissions, the use of which is important for powerful and high-speed cars. And the improvement of their design, elimination of weak points in the work will provide such gearboxes with the opportunity to become more widespread on production cars.
Video on the topic
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 rest, as can be done in a classic manual gearbox with a search switching 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, in sequential gearboxes, gears of a larger size are often used to compensate for this disadvantage.
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 transmissions. 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 transmission 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 cars. 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 the design features of the sequential gearbox, and without unnecessary 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.
Hello everyone! Imagine the situation. You have saved up money and are thinking about buying a car. Not the last question will be the choice of gearbox. And then the thought arises - buy yourself a machine gun or opt for good old mechanics. After all, it would seem that there could be more. But no. There is also a sequential gearbox.
I did not invent it and the device really exists. Although practice and communication even with friends proves that not everyone knows such a name. And even more so, not everyone can immediately say what it is and how it works.
So that you do not fall face down in the dirt and become a real expert in the field of gearboxes, I propose to understand this topic in more detail. Maybe someone after that wants to take a car with a sequential checkpoint.
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 it is possible to "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 horsepower under the hood, and which are used for family trips, there is no need for an SCR.
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 strengths and weaknesses of sequencers.
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. The electronic unit and hydraulics ensure the minimum time required for changing 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.
That's all I wanted to tell you. Thank you for the attention! Hope you enjoyed it.
