Mechanical box gearboxes are no longer the most common type of gearbox used on cars today. However, it still remains quite in demand due to its reliability, design simplicity and maintainability. The manual transmission got its name from the "manual" (or mechanical) method of gear shifting. The transmission belongs to stepped boxes, in which the torque is changed in steps (gears). A manual transmission is considered the most reliable, but also the most difficult to operate, especially for a novice driver.

The principle of operation of a manual transmission

Manual Transmission

Principle of operation manual transmission next: the torque from the engine through the clutch is transmitted to the input shaft of the gearbox, then converted using pairs of interacting gears and then transmitted to the wheels. Each pair of gears (stage) has a specific gear ratio that converts the rotational speed and torque of the engine's crankshaft. Moreover, if the transmission increases the torque, then the rotation speed decreases and vice versa. In the first case, the gear will be called downward, and in the second - upward.

The gear ratio is determined by the ratio of the number of teeth of the output and input gears in a pair. In turn, the number of teeth directly depends on the size of the gear itself: the more teeth, the larger the diameter of the gear. For example, first gear has the largest gear ratio, and therefore the input gear (on the input shaft) is at its smallest size and the output gear at its highest. Gear shifting in a manual gearbox occurs only when the clutch pedal is depressed, since it is necessary to interrupt the flow of power transmitted from the engine.

The movement of a car equipped with a manual transmission always starts from the first gear. The exception is heavy trucks- there it can be done from the second transfer. To do this, you must manually move the lever selector to the appropriate position. The transition to higher gears is carried out by sequential gear changes one after another. The very moment of switching the speed depends on the readings of the speedometer and tachometer, since each gear is designed to work in a certain range of engine rpm.

Types of manual transmissions

By the number of stages, the manual transmission is mainly divided into:

• 4-stage;
• 5-stage;
• 6-step.

The most common mechanic is the 5MT transmission, i.e. five-speed gearbox gear.

Depending on the number of shafts, the following types of gearboxes are distinguished:

• twin-shaft mechanical transmissions installed on cars front wheel drive cars;
• three-shaft manual transmissions, which are mainly used on rear wheel drive vehicles as well as on trucks.

Mechanical transmission device

Mechanical gearbox device

Structurally, a manual transmission consists of the following elements:

• driving or primary shaft;
• slave or output shaft;
• intermediate shaft (for 3-shaft manual transmission);
• gears of the primary and secondary shafts;
• gear selection mechanism;
• synchronizer couplings (synchronizers);
• crankcase;
• main gear;
• differential.

At the same time, the device and the principle of operation of the two-shaft and three-shaft transmissions differ from each other.

Twin-shaft gearbox: design and principle of operation

Two-shaft manual transmission scheme

This type of box is the most common. The torque from the engine is transmitted through the clutch to the input shaft. Depending on the design of a particular gearbox, some of the gears on the input and output shafts are rigidly fixed to them, and some rotate freely. Also, at least one synchronizer is located on each shaft. The gears of the input and output shafts are in constant mesh with each other. It is very simple to understand which of them are fixed and which rotate: the gears near the synchronizers always rotate on the shaft.

Gear main gear rigidly fixed to the driven shaft. The torque from the output shaft to the wheels of the vehicle is transmitted by the final drive and differential. The latter ensures the rotation of the wheels at different angular speeds.

The gear selection mechanism in a two-shaft gearbox is located in the gearbox housing and consists of forks and rods that move the synchronizer couplings. The mechanism is equipped with protection against simultaneous engagement of two gears.

The principle of operation of a two-shaft transmission is as follows:

1. IN neutral position of the gear lever, the torque from the engine is not transmitted to the drive wheels, the gears on the shafts rotate freely.
2. When moving the lever, the driver moves the synchronizer sleeve with a suitable fork through a system of cables or rods.
3. The clutch synchronizes the angular speeds of the corresponding gear and the shaft on which the synchronizer is located.
4. The synchronizer clutch engages with the gear and the torque begins to be transmitted from the primary shaft to the secondary.
5. There is a transfer of torque from the engine to the drive wheels with a given gear ratio.

For reversing, an additional shaft with an intermediate gear is used reverse.

Torque transmission schemes for each gear:

Neutral position

1st gear

2nd gear

3rd gear

4th gear

5th gear

Reverse

Three-shaft gearbox: device and principle of operation

The difference between three-shaft mechanics and two-shaft mechanics is that three types of shafts are used here. In addition to the driven and driven, an intermediate shaft is also used.

Primary shaft connected to the clutch transmits the torque to the intermediate. The transmission takes place through the corresponding gear - thus, the shafts are in constant mesh.

Three-shaft manual transmission device

Intermediate shaft located parallel to the primary, all gears on it are rigidly fixed.

On the same axis with the primary there is a secondary shaft. Responsible for this thrust bearing on the drive shaft, which includes the output shaft. In this case, the gears of the driven shaft can rotate freely and are not rigidly fixed with the shaft. The pinion shaft gears are in constant mesh with the intermediate shaft gears. Therefore, in the neutral position of the gearbox, the torque from the input shaft is transmitted to the intermediate shaft and then to the gears of the output shaft. But since they rotate freely on the shaft, the car does not move.

Synchronizers are located between the gears of the output shaft, the work of which is to align angular velocities gears of the secondary shaft with the angular speed of the shaft itself due to frictional forces.

Synchronizers are rigidly fixed to the shaft and due to spline connection can move along it in the axial direction.

Unlike a two-shaft gearbox, the shift mechanism in a three-shaft transmission is located on the gearbox housing and consists of a control lever and rods with forks. The mechanism is also equipped with a locking device to prevent the simultaneous engagement of two gears.

He can also have and remote control... Wherein distance mechanism shifting is provided by a rocker or articulated cables.

The principle of engaging gears in a three-shaft gearbox is similar to the principle of operation of a two-shaft transmission.

A little about the manual transmission synchronizer

The synchronizer is used for shockless gear shifting by equalizing the angular speeds of the shaft and gear. Structurally, the synchronizer consists of a coupling, two locking rings, three crackers and two wire rings.

In the process of engaging the gear, the fork moves the clutch to the desired gear, where the locking ring first moves. The resulting frictional force due to the difference in the angular velocities of the elements turns the locking ring until it stops. Further movement synchronizer clutches and engagement occurs only after the angular velocities are equalized. You can read more about the synchronizer in our article.

Advantages and disadvantages of manual transmission

For clarity, positive and negative sides a mechanical gearbox is represented in the form comparative table.

Advantages	Flaws
The cost and weight of the box is lower in comparison with other types of gearboxes	Less comfort for the driver compared to other gearboxes
High dynamics of acceleration, fuel efficiency and efficiency	Tiring gear shifting for the driver
High reliability due to simple design	The need for periodic replacement of the clutch

The existing types of gearboxes, in fact, are the answer to the demand of motorists. The box, together with the steering wheel, makes it possible to effectively control the capabilities of a modern car. Someone likes comfort, someone quickly gets tired of management, someone does not know how to do anything at all and is afraid of everything. IN modern classification there are three main types of gearboxes and their variants:

• mechanical system, manual way of gear shifting;
• automatic multistage gearbox;
• stepless variator system;
• robotic box.

Despite the fact that the latter type is considered a variant of a manual transmission, the existing differences from the classic scheme allow it to be distinguished on a separate line. You can safely define it as a separate type of gearbox.

Engine internal combustion is not able to work effectively in the widest range of rotational speeds, therefore, various types of gearboxes are used, which reduce the rotational speed of the transmission working shafts. This is done either with a set of gears and wheels, as in the main types of gearboxes, or with the help of pushing belts and pulleys, in the variator scheme of the gearbox.

The variator gearbox most of all meets the lifestyle of a modern person and allows you to completely abandon transmission control. The first requires maximum driver involvement in wheel speed and torque control. The automatic machine greatly facilitated the life of a person behind the wheel, but requires careful attention to its work.

Before answering the question - which type of gearbox is better to choose, you should determine your attitude to the car and the degree of your participation in driving.

Simple and reliable manual systems

Mechanical system shift, also called "mechanics" or "handle" - the most common and simple type of gearbox. IN modern cars it is presented in two types:

• multi-shaft, in which the gears are located on two or three parallel shafts and engage alternately depending on the required gear ratio;
• planetary, in which gears and gear wheels are in constant engagement in several rows, the choice of a pair with the required gear ratio is performed using clutches or friction packages.

In wheeled transport, the planetary type of mechanics is used only in automatic transmissions, in mountain bikes and military equipment... The planetary machine is more compact and lighter than the multi-shaft type of mechanism, but it is much more expensive to manufacture.

Modern Cars with front-wheel drive have a two-shaft scheme and a minimum of 5 gears for forward and one reverse. More expensive car models can be equipped with six-speed gearboxes gear. In this case, the 5th and 6th are increasing - the output shaft of the gearbox rotates with more high turnover engine crankshaft. This is more than enough for manual control.

The main problem of a manual transmission is to smoothly and shocklessly engage pairs of helical gears with different angular speeds when shifting at the command of the handle. To equalize the revolutions in the box, each pair of gears is equipped with a synchronization ring made of bronze.

When changing gear, the driver disengages the clutch, thereby allowing the synchronizers to equalize the rotation speeds of the gears. Then the shift knob either directly or through the linkage system or cable drives, move the gear clutch inside the box body, thereby engaging the required pair of gears. All that remains is to release the clutch pedal and continue driving.

Such mechanical boxes are called synchronized. It is quite simple and convenient to operate them if you have a certain skill in driving a car. True, incomplete disengagement of the clutch, slipping or other problems with disengaging the transmission lead to the fact that the synchronizers of the mechanics begin to wear out intensively, up to the impossibility of engaging the gear without intermediate setting the handle to the neutral position. Go to next gear occurs after re-squeezing the clutch. A similar way switch was widely used in the past and is used now on freight transport with mechanics not equipped with a synchronizer system.

Important! Worn out synchronizers, in addition to the difficult engagement of the gear, lead to intensive wear of the gear rims, local chipping of individual sections of the teeth.

A manual transmission is the most reliable and economical, it requires the driver to have sufficient qualifications and hard work to constantly shift gears paired with working out the clutch pedal. But, oddly enough, many drivers deliberately make a choice in favor of mechanics. In their opinion, mechanics, even with increased physical exertion, give more pleasure from driving a car than robotic or automatic transmissions.

Sequential checkpoint, as the highest point in the development of mechanics

It would be more accurate to call this box - a manual transmission with a sequential, or in-line shift method. The idea came from the field of development for sports high-speed cars... A modern sequential gearbox is built according to the scheme of a conventional manual gearbox with electronic control clutch drive and hydraulic drive gear shifting. Feature sequential box adherence to a strict sequence of transmissions.

Advantages of the sequential mechanism include:

• the highest speed of gear shifting;
• adherence to the switching sequence makes it possible to work "painlessly" with very high turnover engine and power;
• the way of control with the help of paddle shifters allows you to control the movement quite comfortably even on high speeds or in difficult road conditions.

IN similar boxes use spur gears and do not use synchronizers. The alignment of the speeds of rotation of the gear and wheel is carried out by a computer using a speed sensor. Instead of a toothed clutch, there is a cam mechanism for engaging gears. Thanks to this, the speed switch-on time is about 70-80% less than that of conventional mechanics. For the operation of hydraulic drives, a separate unit is used - an accumulator working fluid high pressure.

Robotic transmission systems

Unlike sequential systems, the robotic form of the box has an electromechanical drive for switching on a pair of gears. The basis of the scheme is a mechanical gearbox, built on a system of two working shafts-gear rows. Even numbers are collected on one shaft, odd numbers on the other. Each of the shafts has its own clutch disc and can be switched on and off independently.

This type of box uses a preselective mode. The trick of the design is that the computer in advance, using the data on the operating mode of the transmission, calculates the most suitable next gear for engaging. With the help of a solenoid, it engages it in the opposite row of gears with the clutch disengaged. At the moment of switching, all that remains is to engage the clutch and continue driving. Due to this, the switching takes place with a very high speed.

In a kind, robot boxes occupy an intermediate position between automatic transmissions and mechanics. At the same time, in terms of the functions performed and the degree of computerization, this type of box can be called more automatic than the existing hydromechanical systems.

The most famous and advertised robotic type of gearbox is called the seven-speed DSG gearboxes installed on VW models with a small engine volume. Reviews about the work - from advertising and laudatory enthusiasm to openly negative.

If you decide to buy a car with a similar system gear, it is worth considering the following:

1. Robotic box- a very complex mechanism, least of all this type of box is intended for high-speed burning of rubber in crazy races. The boxes are difficult to manage, maintain and repair.
2. You should get used to driving on DSG for at least two weeks. To fans of mechanics, this view seems slow and unpredictable, to drivers who have changed from hydromechanical boxes- twitching inappropriately.
3. Already, the quality of robots allows us to provide 5 year warranty and 150 thousand mileage.

Interesting! With all the criticisms, robots are cheaper to manufacture, have more high efficiency and, according to experts, it is possible that this particular type will oust outdated hydromechanics from the market passenger cars.

The most difficult type of transmission - automatic machines and variators

The more functions a gearbox performs, the more difficult it is to manufacture, the lower the reliability and the higher the cost. All types of automatic car transmissions have always been and remain the most expensive and uneconomical. The design of this type is represented by hydromechanical and adaptive gearboxes. The scheme is based on two main units - a torque converter and a planetary gearbox.

In modern automatic transmissions, the torque converter acts as a compensator that increases or decreases the main gear of the planetary gear by a small amount. Thus, joint work The two aggregates provide the optimum transmission gear ratio for specific conditions.

Large losses in hydraulics forced engineers to somewhat improve the operation of this type of machine. Now the operation of the torque converter at speeds exceeding 20 km / h is blocked by the clutch, and the transmission of torque is carried out directly through the clutches to the planetary gearbox.

In some cases, instead of connecting a torque converter, its functions in transient modes are provided by slipping of the friction lining packages, which is simpler and more efficient.

One of the varieties automatic transmission is an adaptive automatic transmission in which computer unit control is the selection of the most suitable gear ratio in the planetary box.

This kind automatic box while it remains out of competition in the transmission of a car off-road, SUVs and cars with a large engine displacement. It is difficult to maintain and repair, requires high qualifications and high-quality Supplies.

CVT systems

As a result of 30 years of evolution of the first variators for low-power sidecars and scooters, technologists managed to bring the level of reliability and durability of the pushing belt (the main element of a continuously variable variator) to an acceptable mileage of 150 thousand km. The push belt itself is an engineering marvel. It is made of a large number of exactly the same metal elements so that the belt can be flexible and rigid at the same time.

In operation, it interacts with two pulleys - input and output, providing almost any gear ratio of the gearbox. Modern CVTs have received an acceptably high efficiency and the ability to work with engines up to 100 hp. The variator can be called the first of the systems that are truly capable of continuously changing the gear ratio of the transmission.

This type of automation does not like slipping, it is extremely vulnerable with low quality hydraulic fluid... In most cases, the variator is equipped with a torque converter.

Benefits - very accurate selection required transmission ratio. This type of box is capricious, expensive to manufacture and maintain, and is unlikely to leave the niche in the near future. small cars.

More information about different types Checkpoint on video:

Cars with a manual transmission, which is abbreviated as manual transmission, until recently constituted an absolute majority among other vehicles with different ones.

Moreover, a mechanical (manual) box and today remains a fairly common device for changing and transmitting engine torque. Next, we will talk about how the "mechanics" is arranged and works, what the checkpoint scheme of this type looks like, and also what advantages and disadvantages this solution has.

Read in this article

Mechanical transmission diagram and features

Let's start with the fact that this type of gearbox is called mechanical due to the fact that such a unit assumes manual switching gear. In other words, on cars with manual transmission, the driver himself switches gears.

Let's go further. The "mechanics" box is stepped, that is, the torque changes in steps. Many car enthusiasts know that the gearbox actually has gears and shafts, but not everyone understands how the unit works.

So, a stage (aka transmission) is a pair of gears (drive and driven gear) interacting with each other. Each such stage provides rotation with one or another angular velocity, that is, it has its own gear ratio.

The gear ratio should be understood as the ratio of the number of teeth of the driven gear to the number of teeth on the driving gear. In this case, different gearbox stages receive different gear ratios. The most low step (low gear) has the largest gear ratio, and the highest stage ( overdrive) has the smallest gear ratio.

It becomes clear that the number of steps is equal to the number of gears on a particular gearbox (four-speed gearbox, five-speed gearbox, etc.). Note that the vast majority of cars now have a five-speed gearbox, less often there are manual transmissions with 6 or more steps, and quite common previously, 4-speed manual transmissions gradually receded into the background.

Mechanical transmission device

So, although there can be many designs of such a box with certain features, however, at the initial stage, two main types can be distinguished:

• three-shaft gearboxes;
• two-shaft boxes;

On cars with rear wheel drive, a three-shaft manual transmission is usually installed, while a two-shaft gearbox is installed on front-wheel drive passenger cars... At the same time, the device of mechanical gearboxes of both the first and second types may differ significantly.

Let's start with a three-shaft manual gearbox. Such a box consists of:

• drive shaft, which is also called primary;
• intermediate shaft of the gearbox;
• driven shaft (secondary);

The shafts are equipped with gears with synchronizers. Also, a gearshift mechanism is included in the gearbox device. These constituent elements located in the gearbox housing, which is also called the gearbox housing.

The task of the drive shaft is to create a clutch connection. The drive shaft has slots for the clutch disc. With regard to torque, the specified torque from the drive shaft is transmitted through the gear, which is in rigid engagement with it.

Affecting the work of the intermediate shaft, this shaft is located parallel to the input shaft of the gearbox, a group of gears is installed on it, which is in rigid engagement. In turn, the driven shaft is mounted on the same axis with the driving shaft.

This installation is realized with an end bearing on the drive shaft. This bearing contains the driven shaft. The gear group (gear block) on the driven shaft does not have rigid engagement with the shaft itself and therefore rotates freely on it. In this case, the group of gears of the intermediate shaft, the driven shaft and the gear of the driving shaft are in constant mesh.

Synchronizers (synchronizer couplings) are installed between the gears of the driven shaft. Their task is to align the angular velocities of the gears of the driven shaft with the angular velocity of the shaft itself by means of friction force.

Synchronizers are in rigid engagement with the driven shaft, and also have the ability to move along the shaft in the longitudinal direction due to the spline connection. Modern gearboxes have synchronizer couplings in all gears.

If we consider the mechanism for shifting gears on three-shaft gearboxes, this mechanism is often installed on the body of the unit. The design includes control levers, sliders and forks.

The box body (crankcase) is made of aluminum or magnesium alloys, it is necessary for the installation of shafts with gears and mechanisms, as well as a number of other parts. The gearbox housing also contains the transmission oil (gearbox oil).

• To understand how a three-shaft type mechanical (manual) transmission works, let's go to general outline consider the principle of its operation. When the gear lever is in neutral, no torque is transmitted from the engine to the drive wheels of the vehicle.

After the driver moves the lever, the fork will move the synchronizer clutch of a particular gear. Then the synchronizer will equalize the angular speeds of the desired gear and the driven shaft. Then the clutch ring gear will mesh with a similar pinion ring, which will ensure the pinion is locked on the driven shaft.

We also add that the car's reverse gear provides reverse gear Checkpoint. In this case, the reverse idler gear, mounted on a separate axle, allows the direction of rotation to be reversed.

Two-shaft mechanical transmission: device and principle of operation

Having dealt with what the three-shaft gearbox consists of, let's move on to the twin-shaft gearboxes. This type The gearbox has two shafts in its device: primary and secondary. The input shaft is the driving shaft, the secondary driven shaft. Gears and synchronizers are fixed on the shafts. Also in the crankcase is the main gear and differential.

The drive shaft is responsible for the connection with the clutch; there is also a block of gears on the shaft in rigid engagement with the shaft. The driven shaft is located parallel to the driving shaft, while the gears of the driven shaft are in constant mesh with the gears of the driving shaft, and also rotate freely on the shaft itself.

Also, the drive gear of the main gear is rigidly fixed on the driven shaft, and synchronizer couplings are located between the gears of the driven shaft. We add, in order to reduce the size of the gearbox, as well as to increase the number of gears, in modern boxes, instead of one driven shaft, 2 or even 3 shafts can often be installed.

On each such shaft, a gear wheel of the main gear is rigidly fixed, while such a gear wheel has a rigid engagement with the driven gear. It turns out that the design actually implements 3 main gears.

The main gear itself, as well as the differential in the gearbox device, transmit torque from the secondary shaft to the drive wheels. At the same time, the differential can also provide such a rotation of the wheels when the drive wheels rotate at different angular speeds.

As for the gearshift mechanism, on two-shaft gearboxes, it is placed separately, that is, outside the body. The box is connected to the switching mechanism with cables or special rods. Connection with cables is more common.

The shift mechanism of the 2-shaft box itself has a lever that is connected with cables to the selection lever and the gear selection lever. These levers are connected to the central shift rod, which also has forks.

• If we talk about the principle of operation of a two-shaft manual transmission, it is similar to the principle of a three-shaft gearbox. The differences lie in the way the gear shifting mechanism works. In a nutshell, the lever can carry out both longitudinal and transverse movements relative to the vehicle axis. During lateral movement, a gear selection occurs, since the force is applied to the gear selector cable, which acts on the gear selector lever.

Further, the lever moves longitudinally, and the force goes already to the gear shift cable. The corresponding lever horizontally moves the rod with forks, the fork on the rod displaces the synchronizer, which leads to blocking of the driven shaft gear.

Finally, we note that also mechanical boxes different types have additional blocking devices that prevent the inclusion of two gears at the same time or an unexpected shutdown of the gear.

Read also

Squeezing the clutch before starting the engine: when to squeeze the clutch and in what cases it is not recommended to do it. Useful Tips and recommendations.

Reasons for difficult engagement of gears on a running engine. Transmission oil and level in the checkpoint, wear of synchronizers and gears of the box, clutch.

Most modern vehicles are equipped with the following types of gearboxes:

• mechanical;

Each type of gearbox has its own design, different from others, its advantages and disadvantages, based on which, when buying a car, a motorist can give preference to one or another device. The device of a manual transmission (manual transmission), which will be discussed in detail in this article, is distinguished by its simplicity, so it is quite easy to understand the principle of its operation.

Mechanism

Before proceeding with the study of the device of a manual transmission (manual transmission) and the principles of its operation, you should describe in detail this mechanism... A manual transmission is an integral part of any vehicle equipped with an internal combustion engine. Its mandatory presence is due to the specifics of the work modern motors having a sufficiently small range of revolutions, within which the maximum values ​​of power and torque are achieved. In addition, any engine has a critical speed value, exceeding which invariably leads to premature wear of the unit, up to and including its failure. Before the transmission of torque to the secondary shaft and to the wheel drive of the vehicle, the manual transmission changes the direction of this vector physical quantity and transforms it. Go to every new step in the manual transmission it is carried out by means of a mechanical movement of the lever to one position or another.

Directly the gearbox mechanism is located in a metal case, inside of which they are poured lubricants ensuring the stable operation of the mechanism. The gearshift lever can be located both in the gearbox itself, and outside it (in the car body). In the case of a remote process of gear shifting, the control drive rod (rocker) is used.

Components of the manual transmission:

• input shaft;
• intermediate shaft;
• secondary shaft;
• additional shaft;
• crankcase;
• synchronizers;
• gear shifting device, which includes locks and locking mechanisms;
• gear shift knob.

Operating principle

The bearings in the crankcase help to rotate the shafts of the device. Each shaft is equipped with a set of gears, on which special teeth are located in various numbers.

The function of synchronizers is to balance the angular velocities of the gears that arise during their rotation. Thanks to their work, the gears shift smoothly without extraneous noise.

Locking mechanisms prevent the possibility spontaneous shutdown gears, while locks prevent multiple gears from being engaged at the same time.

Number of steps and shafts

Today, the most popular is the five-speed gearbox, however, you can often find four-speed and six-speed gears.

The manual transmission may include two or three shafts. Three-shaft mechanisms are equipped with front-wheel drive and rear-wheel drive vehicles(including trucks).

Two-shaft boxes are most often equipped with front-wheel drive cars.

The main differences between gearboxes with a different number of shafts:

• The location of the shafts. In a two-shaft gearbox, the shafts are parallel to each other;
• The transfer process. In a gearbox with three shafts, the transmission is created due to the work of one pair of gears, in a three-shaft gearbox - due to the interaction of two pairs;
• Direct transmission. The two-shaft gearbox does not have a direct transmission.

Otherwise, the manual transmission device has no significant differences in design and, in principle, does not work.

Video

The principle of operation of the manual transmission is clearly shown in the following video:

Any car with an internal combustion engine has a gearbox in its design. There are many varieties of this unit, but the most common type is a manual transmission (manual transmission). Both domestic and foreign cars are equipped with it.

The gearbox is used to change the gear ratio of the rotational speed from the engine to the wheels. The way of switching between the steps (gears) of this reducer is manual (mechanical), which gave the name to the entire unit. The driver independently decides which of the fixed values ​​of the gear ratio (gears in engagement) should be included at the current moment.

Modern manual transmission

In addition, the manual transmission allows you to switch to reverse mode, in which the car moves in reverse direction... There is also a neutral mode when there is no transmission of rotation from the motor to the wheels.

Principle of operation and device

The gearbox is a multi-stage enclosed gearbox. Helical gears have the ability to alternately be in mesh and change the speed between input shaft and the weekend. This is how the transmission works.

Clutch

The manual transmission is paired with a clutch. This assembly allows you to temporarily decouple the motor from the transmission. Such an operation makes it possible to painlessly change gears (steps) without turning off the engine speed.

The clutch unit is necessary because significant torque passes through the manual transmission.

Gears and shafts

In any gearbox of traditional design, they are located parallel to the axis of the shafts on which the gears are based. The common body is usually called the crankcase. The most popular are three-shaft and two-shaft companies.

In three-shaft there are three shafts:

• the first is the presenter;
• the second is intermediate;
• the third is a slave.

The first shaft is connected to the clutch, splines are cut on its surface along which the clutch driven disc moves. From this axis, rotation is transmitted to an intermediate axis rigidly connected to the gear of the input shaft.

The driven shaft of the manual transmission has a specific location. It is coaxial with the leading one and connected to it through a bearing located inside the first shaft. This ensures their independent rotation. The gear blocks from the driven axle do not have a rigid fixation with it, and the gears are delimited by special synchronizer couplings. The latter just sit rigidly on the driven shaft, but are able to move along the axis along the splines.

The ends of the couplings are equipped with toothed rims capable of connecting with the same rims located at the ends of the gears of the driven shaft. The modern gearbox design assumes the presence of such synchronizers in all forward gears.

When the neutral mode is engaged, the gears rotate freely, and all synchronizing couplings are in the open position. When the driver squeezes the clutch and switches the lever to one of the steps, then at this time the fork in the gearbox moves the clutch into engagement with its pair at the end of the gear. So the gear is rigidly fixed with the shaft and does not scroll on it, but provides the transfer of rotation and force.

Most manual transmissions use oblique gears that can withstand more forces than spur gears, and they are also less noisy. They are made of high-alloy steel, after which they are hardened at high frequency frequency and normalized to relieve stress. This ensures maximum service life.

For a two-shaft box, a drive shaft connection with a clutch block is also provided. Unlike a three-axle design, a block of gears is located on the drive axle, rather than one. Intermediate shaft no, but the driven shaft runs parallel to the drive shaft. The gears on both axles rotate freely and are always engaged.

The driven shaft is equipped with a rigidly fixed main gear drive gear. Synchronization clutches are located between the rest of the gears. Such a mechanical transmission scheme in terms of synchronizers operation is similar to a three-shaft scheme. The difference is that there is no direct transmission, and that each stage has only one pair of gears connected, not two pairs.

A two-shaft device of a manual transmission has a higher efficiency than a three-shaft one, however, it has a limitation on increasing the gear ratio. Due to this feature, the design is used only in passenger cars.

Synchronizers

All modern manual gearboxes are equipped with synchronizers. Without them, machines had to do double squeeze so that the peripheral speeds of the gears are equal, and the possibility of switching steps is provided. Also, synchronizers are not installed on a checkpoint with a large number of gears, sometimes up to 18 steps, typical for special equipment, since this is technically impossible. For fast gear shifting sports cars may not have synchronizers in the manual transmission.

Synchronizer manual transmission

Passenger cars used by most drivers are equipped with synchronizers, since the car's gearbox works less friendly without them. These elements provide quiet operation and alignment of gear speeds.

The inner diameter of the hub has spline grooves, due to which movement along the axis of the secondary shaft is carried out. Moreover, such rigidity ensures the transfer of large forces.

The synchronizer works this way. When the driver engages the gear, the clutch moves towards the desired gear. During movement, the force is transferred to one of the locking rings of the clutch. At the expense of different speeds Between the gear and the clutch, the bevel surfaces of the teeth interact by means of frictional force. She turns the locking ring onto the stop.

Synchronizers operation

The teeth of the latter are set against the teeth of the clutch, so subsequent displacement of the clutch becomes impossible. The clutch comes into engagement with a small rim on the gear wheel without any resistance. Due to this connection, the gear is rigidly locked with the clutch. This process takes place in a split second. One synchronizer usually provides two gears.

Gear shifting process

The corresponding mechanism is responsible for the switching procedure. For cars with rear drive, the lever is installed directly on the manual transmission housing. The entire mechanism is hidden inside the body of the unit, and the shift knob directly controls it. This arrangement has its advantages and disadvantages.

• structurally simple solution;
• ensuring the clarity of switching;
• more durable design for operation.

• there is no possibility of using a design with a rear motor;
• not used on front wheel drive vehicles.

Cars with a front drive axle are equipped with a gear lever in the following places:

• floor between the driver's and front passenger seats;
• on the steering column;
• in the area of ​​the instrument panel.

Remote control of the gearbox for front-wheel drive cars is carried out using rods or rockers. This design also has its own characteristics.

• comfortable, more independent arrangement of the gear lever;
• vibration from the box is not transmitted to the manual transmission lever;
• provides great freedom for design and engineering layout.

• less durability;
• backlash may appear over time;
• periodic qualified adjustment of rods is required;
• legibility is less accurate than positioning directly on the body.

Although there are various actuators for the gear on / off mechanism, the mechanism itself in most gearboxes has a similar design. It is based on movable rods, which are located in the housing cover, as well as forks rigidly fixed on the rods.

Gearshift mechanism Lada Granta

The forks fit in a semicircle into the groove of the synchronizer clutch. In addition, the manual transmission contains devices that will protect the mechanism from disengagement or from unauthorized disengagement of the gears, as well as from the simultaneous activation of two stages.

Advantages and disadvantages of manual transmissions

All types of mechanisms have their own advantages and disadvantages. Consider them at the manual transmission.

Dignity:

• the design has the lowest cost in comparison with analogues;
• unlike hydromechanical, it has less weight and higher efficiency;
• does not need special conditions cooling compared to automatic transmissions;
• an average car with a manual transmission has more economical parameters and acceleration dynamics, in contrast to an average car with an automatic transmission;
• simplicity and engineering sophistication of the design;
• high degree of reliability and long service life;
• does not need specific maintenance and scarce consumables or repair materials;
• the driver has more wide range using driving techniques in extreme conditions ice, off-road, etc .;
• the car is easily started by pushing and can be towed at any speed and at any distance;
• there is technical capability complete separation of the engine and transmission, in contrast to the hydromechanical automatic transmission.

Flaws:

• full decoupling is used for gear shifting power plant and transmission, which affects the time of the operation;
• specific driving skills are required to ensure smooth gear changes;
• failure to shift smoothly gear ratio, since the number of steps is usually limited to a number from 4 to 7;
• low resource of the clutch unit;
• the driver, when driving a car with a manual transmission for a long time, appears more fatigued than when driving an "automatic" transmission.

In most countries with a higher income of the population, the number of cars produced with manual transmission has been reduced to almost 10-15%.