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

The gearbox is used to change the rotational speed ratio from the engine to the wheels. The method of switching between stages (gears) of this gearbox is manual (mechanical), which gave the name to the entire assembly. The driver independently decides which of the fixed values gear ratio(gears in mesh) must be turned on at the current moment.

Modern manual transmission

In addition, the manual transmission allows you to switch to the mode reverse, 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.

Operating principle and device

The gearbox is a multi-stage closed gearbox. Helical gears have the ability to alternately be in mesh and change the speed between input shaft and weekends. This is the principle of operation of the gearbox.

Clutch

The manual transmission works in tandem with the clutch. This unit allows you to temporarily disconnect the engine from the transmission. This operation makes it possible to painlessly change gears (stages) without turning off the engine speed.

A clutch unit is necessary because a significant amount of torque passes through the manual transmission.

Gears and shafts

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

Three-shaft models have three shafts:

• the first is the leader;
• the second is intermediate;
• the third is the follower.

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 the intermediate axis, rigidly connected to the input shaft gear.

The driven shaft of the manual transmission has a specific location. It is coaxial with the drive 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 clutches. The latter 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 gear rims that can be connected to the same rims located at the ends of the driven shaft gears. Modern device gearbox requires the presence of such synchronizers in all forward gears.

When the neutral mode is turned on, the gears rotate freely, and all synchronizer clutches are in the open position. When the driver depresses the clutch and switches the lever to one of the stages, then at this time the fork in the gearbox moves the clutch into engagement with its pair at the end of the gear. This way the gear is rigidly fixed to the shaft and does not rotate on it, but ensures the transmission of rotation and force.

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

For a two-shaft box, a connection between the drive shaft and the clutch block is also provided. Unlike the three-axle design, the drive axle has a block of gears, rather than just one. There is no intermediate shaft, but the driven shaft runs parallel to the drive one. The gears on both axles rotate freely and are always in mesh.

The driven shaft is equipped with a rigidly fixed drive gear of the main gear. Synchronization clutches are located between the remaining gears. Such a scheme manual transmission gears in terms of the operation of synchronizers 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 connected gears, rather than two pairs.

The two-shaft device of a manual transmission has greater efficiency than the 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, the machines had to do a double squeeze so that the peripheral speeds of the gears were equal, and the ability to switch stages was ensured. Also, synchronizers are not installed on gearboxes with a large number of gears, sometimes up to 18 steps, typical for special equipment, since this is technically impossible. For quick gear shifting sports cars Manual transmissions may not have synchronizers.

Manual transmission synchronizer

Passenger cars used by most drivers are equipped with synchronizers, as the car's gearbox operates less friendly without them. These elements ensure quiet operation and equalization of gear speeds.

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

The synchronizer works in this way. When the driver engages the gear, the clutch is fed towards the desired gear. During movement, the force is transferred to one of the coupling locking rings. Due to the different speeds between the gear and the clutch, the conical surfaces of the teeth interact through friction. She turns the locking ring against the stop.

Synchronizer operation

The teeth of the latter are installed against the teeth of the coupling, so subsequent displacement of the coupling becomes impossible. The clutch engages without resistance with the small ring on the gear. Due to this connection, the gear is rigidly locked with the clutch. This process is carried out in a fraction of a second. One synchronizer usually provides two gears.

Gear shift process

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

• a simple solution in terms of design;
• ensuring clear switching;
• more durable design for use.

• there is no possibility to use a design with a rear engine;
• not used on front wheel drive vehicles.

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

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

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

• comfortable, more independent location of the gear shift lever;
• vibration from the gearbox is not transmitted to the manual transmission lever;
• provides greater freedom for design and engineering layout.

• less durability;
• Over time, backlashes may appear;
• periodic qualified adjustment of rods is required;
• the clarity is less precise, in contrast to the location directly on the body.

Although there are different drives 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 to the rods.

Gear shift mechanism Lada Granta

The forks fit in a semicircle into the groove of the synchronizer coupling. Additionally, the manual transmission contains devices that will protect the mechanism from not engaging or from unauthorized disengagement of the gears, as well as from simultaneous activation of two stages.

Advantages and disadvantages of manual transmissions

All types of mechanisms have their own advantages and disadvantages. Let's look at them for manual transmission.

Advantages:

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

Flaws:

• Full disengagement is used to change gears power plant and transmission, which affects the operation time;
• Specific driving skills are required to ensure smooth gear shifting;
• inability 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;
• When driving a car with a manual transmission for a long time, a driver experiences greater fatigue than when driving an “automatic” transmission.

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

April 19, 2017

To move a car and accelerate it, engine power (torque) must be converted and transmitted to the drive wheels. But how to implement this when the motor is already running at Idling and him crankshaft rotates, but the car stands still? The problem can be solved by the simplest transmission unit of the currently existing ones is a manual transmission (manual transmission).

Besides her, in modern cars automatic and variable transmission types are used, but these are more complex and expensive devices.

Why do you need a manual transmission?

The first reason is clear - you need to somehow connect the rotating engine shaft to the wheel drives in order to get moving. There is also a second one: the power unit develops operating power (in other words, maximum torque) when it reaches a certain number of revolutions crankshaft. For most gasoline engines this threshold is 3000 rpm, for diesel engines – 2000 rpm.

Until the crankshaft speed reaches the lower threshold, the engine will not be able to develop the required power and create enough force to move.

For dummies, that is, beginners who want to understand the work automotive components, the following explanation is offered:

1. During work on site (idling), the crankshaft speed is 800-900 rpm. To start moving, the developed power is not enough and you need to increase it by pressing the gas and increasing the speed to 2-3 thousand per minute. At this moment, you need to connect the wheel drive, which is done using the gearbox.
2. Without a manual transmission, the acceleration of the car will be smooth and incredibly long, and if there is an incline, the car will never accelerate. The reason is the same - lack of power. To increase dynamics, you need a force converter that can slow down the rotation but increase the torque.
3. To turn and park, the car needs reverse gear, which is also provided by a manual transmission.

If a gear with gears is installed between the wheel drive and the crankshaft different sizes, then the wheels will spin slower. But at the same time, the force on each wheel will increase (in the jargon - traction) and the acceleration of the car will accelerate. And the smooth connection of the rotating elements will be ensured by another manual transmission unit - the clutch.

Clutch operation

The following example will help you understand the principle of operation of the clutch assembly: imagine a rotating metal rod with a disk at the end, symbolizing a crankshaft with a flywheel. If you bring another disk to the plane of the disk, then after contact it will also begin to spin. So in general outline and the car clutch operates, only the second disc is mounted on a shaft that goes further to the gear transmission.

The system operates due to frictional force, so the contacting surfaces have a special anti-friction coating. Clutch disc in mechanical transmission moves with a fork-shaped lever. The lever is not mechanically connected to the clutch pedal; it is moved by a hydraulic cylinder. Pressing the pedal compresses the fluid in this cylinder, the piston extends and moves the lever.

The clutch operation algorithm when moving from a standstill is as follows:

1. At idle speed the crankshaft and input shaft The manual transmission spins because the discs are engaged.
2. By pressing the pedal, the driver moves the disc and the transmission shaft stops. It can now be connected to the gear train by selecting the first speed.
3. By pressing the gas, the driver achieves an increase in speed and slowly releases the clutch pedal. The discs engage again and the car moves off.

It is necessary to further break the mechanical connection using the clutch when switching to another speed. To understand this process, you need to understand how the gearbox itself works.

Mechanical transmission operation

The unit consists of the following main elements:

• housing with oil sump;
• three shafts with gears - primary, secondary and intermediate;
• synchronization devices;
• shift handle with fork drives for moving gears.

Using the handle, the driver changes pairs of gears that mesh with the drives from the engine and wheels. The gears are selected in such a way as to provide the required torque on the wheel drive when different modes movement. The first stages of the output shaft use larger diameter gears to make the final drive rotate more slowly but with more force. At speeds III, IV and V, the size of the gears decreases and, as a result, when moving at high speed, the number of revolutions of the drive and crankshaft coincides.

The gear teeth are angled to reduce transmission noise. To prevent the teeth from breaking and causing an impact when they engage while moving, the synchronizer equalizes the rotation speeds of adjacent gears. This happens when the driver depresses the clutch and moves the handle to another position.

A manual transmission is the simplest and most reliable transmission installed on cars with with different load capacities. How it differs from automatic and variable is its low cost with high maintainability, and this also affects the overall price of the car. There is only one inconvenience: the driver needs to constantly manipulate the accelerator and clutch pedals in order to promptly switch to another speed when changing the driving mode.

A manual transmission is a device for stepwise changing the gear ratio of rotation speed from the engine to the drive wheels. When using a manual transmission, the driver selects and engages the desired gear manually (as opposed to an automatic transmission). Name of this device It also reflects the fact that all its functionality is implemented using only mechanical elements, without the involvement of hydraulics or electronics (unlike hydraulic or electric transmissions). The popular, but technically reliable principle of operation of a manual transmission is covered in this publication.

Why did automakers need to introduce gearboxes? Because any internal combustion engine of any car is capable of operating only in a certain limited, and rather small, speed range. And the frequency of rotation of the wheels - from starting off to driving high speeds– occurs over a much wider range. And it is not possible to select any one universal gear ratio that would provide this entire range, while at the same time making reasonable use of the engine speed range.

To start from a standstill and progressively accelerate a car, as well as when driving off-road, it is necessary to expend more significant work in the physical sense, that is, apply pressure to its wheels more power. That is, at low speeds you need high engine speeds.

On the contrary, when uniform motion a car accelerating on a flat road, its speed is high, and its power and high speed an engine is no longer required - to maintain desired speed, low power is sufficient, and low revs. As the speed increases, the aerodynamic drag engine movement, which requires high speeds and more significant power consumption. The same thing - when moving uphill, you need to increase the traction force.

Hence the need arises to transfer rotation from the engine to the wheels with a certain gear ratio, which could be changed depending on driving conditions. This is one of the pioneers of the global automotive industry - a German engineer Karl Benz I was convinced on the first long (80 km) trip in a car of my own design.

This road trip took place in 1887. Karl Benz and his wife Bertha and their sons were traveling to the inventor’s mother-in-law. The 80-kilometer journey turned out to be very difficult due to imperfections in the design of the first car. On some seemingly small climbs it had to be pushed manually: there was not enough traction force. After this trip, Benz improved the car by providing it with an additional auxiliary gear, a “lower gear,” to increase traction.

This idea is used in gearboxes to this day: the gear ratio must be variable, allowing the use of different ratios between the rotation speeds of the engine crankshaft and the drive wheels.

Of course, Karl Benz's first manual transmission was at first a very primitive device. These were pulleys of different diameters attached to the drive axle. They were connected to the motor by a belt, and with the help of levers the belt could be thrown from one pulley to another. Subsequently, the leather belt and pulley were replaced by a metal chain and sprocket, as on modern “advanced” bicycles.

Wilhelm Maybach first installed gears and a gearbox on a car. In parallel with German auto engineers, around the same years, French ones were also engaged in similar research. The manual gearbox created by Emile Levassor and Louis Panard already used a whole set of gears with different gear ratios for moving forward and one gear for moving backward. As in our time, the front gears were mounted on a secondary shaft, which moved along its axis. This allowed gears of different diameters to mesh with a stationary gear on the input shaft.

The official inventor of a manual gearbox, similar to the modern one, was Louis Renault: in 1899, this young aspiring automaker patented the world's first gearbox based on a system of movable gears and shafts. It was three-speed.

The first person to patent a manual transmission was Louis Renault in his “laboratory”.

The overseas pioneer of the automobile industry, Henry Ford, did not copy the achievements of German and French engineers, but followed his own path. Its manual transmission consisted of several planetary gears (satellites), which rotated around a central (“sun”) gear and were fixed using a carrier. It was precisely this kind of planetary gearbox that was equipped with the first mass-produced production cars"Ford A".

No less important technical solution The invention of the synchronizer, which was made in 1928 by Charles Kettering of General Motors, was more than the invention of a box on gears of various diameters. It made manual transmissions easier to operate, gave them a new impetus for development and “technical longevity.”

More than 120 years have passed since the invention of Louis Renault, but the main principle of the stepped gearbox remains the same. Modern manual transmissions, of course, are much more advanced: they have helical rather than straight gears, and they are more convenient, silent and durable. In general, manual cars are more economical than manual cars. automatic transmission transmission

A manual transmission consists of a set of helical gears of different sizes, which are meshed to create different gear ratios between the engine crankshaft and the drive wheels. The gear ratio becomes a different way of moving both the gears themselves and a special device - the synchronizer. Its task is to equalize (synchronize) the peripheral speeds of the gears engaged in meshing.

The principle is that the higher the gear ratio, the lower the gear. The first gear is called low, and its gear ratio is the largest. On it, the transmission of rotation is carried out from the small gear to the large one and, when high frequency rotation of the crankshaft, the vehicle speed remains low and the traction force remains high. In top gear, accordingly, it’s the other way around. In the neutral position, torque from the engine is not transmitted to the drive wheels, and the car rolls by inertia or stands still.

Most modern mass-produced cars equipped with a manual gearbox have 5 “speeds,” or forward speeds. A few decades ago, most automobile manual transmissions were four-speed. Manual transmissions with six or more speeds are usually equipped with “charged” ones. sports cars or jeeps.

WITH technical point In general, a manual transmission is a closed-stage gearbox. The working elements of its design are gears - gears that alternately come into engagement, changing the speed of the input and output shaft, as well as their frequency. Switching of connections and gear combinations occurs manually.

A manual gearbox can only function in conjunction with a clutch. This unit is designed to temporarily disconnect the engine and transmission. This operation is necessary for a painless and safe transition of gearing from one gear to another, without turning off the engine speed, and while maintaining it completely.

The layouts of mechanical gearboxes that have become widespread have become two- and three-shaft. They are named after the number of parallel shafts on which helical gears are located.

A three-shaft manual transmission has three shafts: drive, intermediate and driven. The first one is connected to the clutch; there are splines on its surface. The clutch driven disc moves along them. From this shaft, rotational energy is transferred to an intermediate shaft rigidly connected to it by a gear.

The driven shaft is coaxial with the driving shaft, connected to it through a bearing, which is located inside the first shaft. Therefore, these axes are provided with independent rotation. Blocks of “different caliber” gears of the driven shaft do not have a rigid fixation with it, and are also delimited by special synchronizer couplings. Here they are rigidly fixed to the driven shaft, but can move along the shaft along the splines.

At the ends of the couplings there are gear rims that can be connected to similar rims at the ends of the driven shaft gears. Modern standards Gearbox production requires the presence of such synchronizers in all forward gears.

In a two-shaft manual transmission, the drive shaft is also connected to the clutch unit. Unlike a three-axis design, the drive axle has a set of gears, rather than just one. There is no intermediate shaft, and the driven shaft is parallel to the drive one. The gears of both shafts rotate freely and are always in mesh.

The driven shaft has a rigidly fixed main gear drive gear. Between the remaining gears there are synchronization clutches. In terms of the operation of the synchronizers, this type of manual transmission is similar to a three-shaft arrangement. The difference is that there is no direct transmission, and each stage has only one pair of connected gears, and not two pairs.

At one end of the driven shaft, the main gear is in rigid engagement. The differential operates in the final drive housing.

The two-shaft layout of a manual transmission has greater efficiency than a three-shaft one, but it has limitations on increasing the gear ratio. Due to this feature, the two-shaft manual transmission design is used exclusively in passenger cars.

IN in rare cases Modern cars can also use four-shaft gearboxes. But according to the principle of their operation, they also correspond to two-shaft ones - without intermediate shaft, with transmission of rotation from the primary shaft directly to the secondary ones. Most often, these are manual transmissions with 6 gears. forward travel. In them, torque is transmitted from the input shaft to final drive through the first, second and third secondary shafts, the end gears of which are constantly meshed with the final drive gear.

Reversing the car is ensured by an additional shaft with its own special gear. When it comes into engagement, the driven shaft begins to rotate in the opposite direction. There is no synchronizer in reverse gear, since reverse gear is only engaged when the car comes to a complete stop. In any case, this is how it should be done. Therefore, on the manual transmission of cars from many manufacturers there is protection against accidental engagement of reverse while driving (you need to lift a special ring on the lever to move it to the reverse position).

When the neutral mode is turned on, the gears rotate freely, and all synchronizer clutches are located in the open position. When the driver depresses the clutch and shifts the lever to one of the stages, a special fork in the gearbox moves the clutch into engagement with the corresponding pair at the end of the gear. And the gear is rigidly fixed to the shaft and does not rotate on it, but ensures the transmission of rotation and force energy.

While driving, the gear shift mechanism is activated from the driver's seat of the vehicle using the gear lever. This lever moves the sliders with forks, which, in turn, move the synchronizers and engage the desired speed.

The pairs of gears of the two lowest gears have the largest gear ratios (at passenger cars– usually from 5:1 to 3.5:1), and are used for starting and progressive acceleration, as well as when it is necessary to constantly move at low speeds, or off-road. When driving in lower gears, even at high engine speeds, the car will drive quite slowly, but its power and torque will be fully used. On the contrary, the higher the gear, the higher the speed of the car at the same level of engine speed, and the less its traction force. In higher gears, the car will not be able to move away or move forward. low speeds. But it can move at high speeds, up to the maximum provided, at medium engine speeds.

In the absolute majority modern manual transmissions gears with oblique teeth are located, which can withstand greater forces than straight teeth, and they are also less noisy in operation. Helical gears are made from high-alloy steel, and at the final stage of production, high-frequency hardening and normalization are performed to relieve stress, ensuring the durability of the parts.

Before the advent of synchronizers for shockless inclusion of more high gear drivers had to perform a double squeeze, with mandatory work for several seconds in neutral gear, to equalize the peripheral speeds of the gears. And to move to more low gear it was necessary to re-gear in order to equalize the speed of the drive and driven shafts. After the introduction of synchronizers, the need for these manipulations disappeared. And the gears became protected from shock loads and premature wear.

However, these “skills from the past” can also be useful for a modern passenger car. For example, they will help you change gear if the clutch fails, or if there is a need for sudden engine braking when the service brake system has failed.

Internal combustion engines, both gasoline and diesel, have a fairly narrow operating range. A manual transmission is required to ensure optimal performance power unit.

Changing the gear ratio is done manually, usually by moving the lever from one position to another. To ensure switching, the power flow is broken using a mechanical clutch.

Excursion into history

The first cars did not have the usual gearbox with gears, the force was transmitted to the drive wheels by a belt. This device was used by Karl Benz - to increase speed, the driver needed to throw a ring from one pair of pulleys to another. Wilhelm Maybach was the first to use gears in transmissions; cars of his design had mechanical gearboxes.

The transmission of torque from it to the drive wheels was carried out using a steel chain. At the beginning of the 20th century, the coaxial box appeared on cars by Louis Renault, who was also the inventor of the driveshaft.

At first, the automotive industry was dominated by a spaced arrangement of units, in which the gearbox was located separately from the power unit. Torque was transmitted through a special shaft, as was the case on the BMW 501 model.

The manual transmissions of the first releases were very complex; operating them required considerable effort and good skills. In 1928, American engineer Charles Kettering from General Motors suggested a device for synchronization. First lucky box, equipped with such a mechanism, was installed on the Corvette car. On the European continent, ZF has become a leader in the development of transmissions.

The firmly established name of manual transmission has the following abbreviation - mechanical gearbox. Previously, the first letter P in the name meant the word change, but over time it was replaced with a more suitable meaning. Abbreviated name for manual transmission technical descriptions often appears with a number indicating the number of steps.

A modern manual transmission has a fairly advanced device that, in addition to shifting gears while moving, performs a number of functions:

• ensuring the vehicle moves in reverse;
• separation of the transmission and the running engine of the car during short stops;
• Availability neutral position box allows you to start the engine.

Cars equipped with this type of transmission, all other things being equal more economical than cars with automatic transmission.

Operating principle of manual transmission

The car starts moving, driving slowly along bad road causes great resistance. A car with a manual transmission in this mode requires the highest possible torque.

At the same time, the gearbox performs the functions of a reduction gear, even at high speeds vehicle moves at a relatively low speed. After acceleration stops, the driver switches the mode, and the crankshaft speed returns to the optimal range.

Uniform movement along the plane requires less effort, which is ensured by higher gears.

The operating principle of a manual transmission is to create connections between the drive (input) shaft and the driven (output) shaft through combinations of gears with different numbers of teeth. This allows the transmission to be adjusted to changing vehicle driving conditions.

For dummies, as non-specialists are commonly called, the principle of operation of a manual gearbox can be explained in just a few words. The device ensures normal engine operation by changing the speed, increasing or decreasing the force on the drive wheels. This allows you to hold best mode operation of the power unit when starting, accelerating and decelerating.

This principle of manual transmission operation is preserved in all cars: with all-wheel drive, rear-wheel drive, and front-wheel drive. The transmission design in each case has its own characteristics, but the main design elements and their purpose are preserved. Changing the gear ratio occurs due to the introduction of a certain combination of gears with different numbers of teeth.

These ratios for each engine are selected individually during design work and full-scale testing. In this case, many factors are taken into account and, first of all, engine parameters. The physical principle of operation of the manual transmission remains unchanged; the driver controls the mode change manually by moving the lever from one position to another.

Video - manual gearbox, operating principle:

You can get a clear idea of ​​the operating principle of a manual transmission after watching a video clip. The schematic animated image perfectly demonstrates the interaction of parts with each other. Such materials provide an understanding of the processes taking place, especially when switching operating modes.

Device

The design of the manual transmission has changed little since its main elements were made and patented. The manual gearbox consists of the following parts and assemblies:

• crankcase;
• input, output and intermediate shafts;
• synchronizers;
• driving and driven gears;
• gear shift mechanism.

The parts assembled in a single housing interact with each other, ensuring the transmission of torque. The design of a manual transmission depends on the design features and the number of shafts - according to this criterion, they are divided into two- and three-shaft. The latter arrangement is called coaxial and in the technical literature it is usually called classical.

Shafts and gear blocks

In this design, the drive and driven shafts are placed in the box housing one after the other. A bearing is installed in the shank of the primary shaft, on which the end of the secondary shaft rests. The absence of a rigid connection allows them to rotate independently of each other at different frequencies and in different directions. Below them there is an intermediate shaft; force is transmitted through gear blocks installed on the specified parts.

In order to reduce the noise of the gearbox, the gears in it are helical. In the manufacture of these parts, a strict tolerance system is used, and much attention is paid to the quality of processing of mating surfaces.

Several gears of different diameters and, accordingly, with different numbers of teeth are rigidly fixed on the drive shaft of a classic manual transmission. In some cases, the knot is made integral, which provides it with maximum strength.

Gears on the secondary shaft can be installed in two ways:

• movable on splines;
• fixed on the hubs.

The connection with the drive shaft in the first embodiment occurs due to the longitudinal movement of the driven gear along the splines until it engages in the drive gear. This scheme is simple and reliable and has become quite widespread.

In another design, longitudinal movement of parts is eliminated and the connection occurs using a sliding coupling.

Video - how torque is transmitted in a manual transmission:

The angular velocities of the drive shaft and driven shaft are equalized using a special device called a synchronizer. In gearboxes sports cars or cars special purpose Instead of these units, claw couplings can be used.

Control mechanisms

Over the entire history of the development of motor transport, many original designs have been developed. The most widespread arrangement is that used in modern units.

The manual transmission is controlled by a special design consisting of the following elements:

• lever;
• drives;
• sliders;
• forks;
• castle;
• gear shift clutches.

Changes in the operating modes of the unit are made by the driver by moving the lever from one position to another. The sliders are activated through the drives. Protection against simultaneous activation is a special blocking mechanism - a lock. In three-way boxes, it makes it impossible to move two sliders while moving the third.

This assembly operates the shift fork, which causes the clutch to move. This item is a thick-walled ring with splines on inner surface. They are in constant engagement with the ring gear of the driven shaft, along which the coupling moves along it. There are similar splines on the side surface of the driven gear.

When changing gears, the lever is first moved to neutral, from which the desired mode is selected. During this time, the synchronizer aligns angular velocities, and the gear is locked by the clutch. Torque from the primary shaft is transmitted to the secondary shaft and then through the main gearbox to the drive wheels.

The synchronizer ensures shockless switching, while its response time does not exceed a few hundredths of a second.

Video - clutch and manual transmission device, a visual story from Toyota:

The smooth operation of a manual transmission largely depends on general condition parts and, in particular, this unit.

The synchronizer is a bronze ring with a gear ring on inside. When the clutch moves, it first presses the part against the conical surface on the sidewall of the driven gear, and the resulting frictional force is sufficient to equalize the rotation speed of the shafts. After synchronization, the gear wheel is locked by the shift clutch.

How to change gears on a manual transmission

The operation and control of cars with a manual transmission has a number of features that the driver needs to know. A natural question arises: how to use a manual transmission? Learning to do this begins in the beginning, from demonstration by an instructor to the development of automatic skill in shifting gears.

How to change gears on a manual transmission is usually indicated on a diagram printed on the outer surface of the lever handle. In general the process looks like this:

• the driver presses the clutch with his left foot;
• moves the lever from one position to another by hand;
• smoothly releases the clutch pedal and smoothly presses the accelerator.

Gear shifts for a manual transmission are carried out in accordance with the diagram indicated in technical documentation to the car. Experienced drivers recommend adhering to the rules below, which will increase the resource of the unit:

• the use of direct transmission (usually fourth) will significantly reduce fuel consumption;
• gear shifting on a manual transmission should be performed strictly in accordance with the instructions developed by the manufacturer;
• Engage reverse gear only after the vehicle has come to a complete stop;
• the clutch pedal is depressed quickly and all the way to the floor, but it should be released smoothly without a jerk;
• On icy or wet roads, coasting is not allowed;
• It is not recommended to change gears when cornering;
• effective on a free road is the technique of engine braking by sequentially lowering the gear to the minimum;
• periodic monitoring of the oil level in the box and timely replacement in progress Maintenance will ensure an increase in its resource.

Video - tips on how to change gears on a manual transmission:

Mastering the techniques of driving a car requires constant practice. The instructor’s actions are shown in great detail; observing them will allow the novice driver to form the correct muscle reactions.

Manual transmission oil

Maintenance of transmission units is carried out in accordance with the service book. In most manual transmission boxes, replacement operating fluid carried out every 50-60 thousand kilometers. During this period, wear products accumulate in it and its lubricating properties are lost.

When performing maintenance, you should pour the fluid for a manual transmission specified in the operating manual. This is especially true for foreign-made machines; the use of inappropriate oil can lead to wear and even breakdown of the unit.

To answer the question which oil is in the manual transmission, you should read the entries in service book, where a note is made about the brand of technical fluid.

The transmission of a modern car sometimes has a more complex design than the engine. It makes the motor more flexible and adapts torque to driving conditions. Despite the emergence of various ultra-modern automatic and robotic transmissions with electronically controlled, the manual transmission has always been and will be the generalissimo of the transmission, and the key to understanding the operating principle of any complex gearbox.

Cog theory

First, it is worth defining the basic concepts and purpose of each gear in the simplest gearbox, then any complex design will not seem like higher mathematics. Everyone understands that a manual gearbox is needed in a car to change the gear ratio of the engine crankshaft revolutions to the number of revolutions of the drive wheels in the end. The gearbox also serves to change the direction of rotation of the output shaft.

Now some numbers to put everything into place. The operating speed range of an internal combustion engine is from 400 to 5-8 thousand revolutions per minute. Moreover, the maximum torque that it is capable of delivering is not achieved at every frequency, but on average, within 3-4 thousand revolutions. In other ranges, the engine is not capable of producing high torque.

The rotation speed of the driving wheel of the machine is approximately 1600-1900 rpm, therefore, to synchronize the operation of the engine with the driving wheels, a mechanism is needed that will most effectively adjust the speed of rotation of the wheels to the engine speed. In practice, it turns out the other way around, however, this mechanism has become a manual gearbox with step transmission torque.

Basics of three-shaft gearbox design

Any traditional gearbox with mechanical type control structurally consists of the following elements:

The gearbox can have a three-shaft or two-shaft design. The rotation of the crankshaft is transmitted to the gearbox using a clutch, which temporarily disconnects the engine and the gearbox input shaft. The primary and secondary shafts on a two-shaft design are located coaxially, but are not connected to each other. Rotation from the primary shaft is transmitted through the intermediate shaft; it engages with the secondary one.

Operating principle of the gearbox

The primary shaft has one gear, which is rigidly fixed to it and transmits torque to the intermediate shaft. The secondary shaft has a whole block of different gears; they can either rotate freely or be rigidly fixed to it using a special mechanism. On modern cars, only helical gears are used because they are less noisy than spur gears.

Switching and selecting the desired pair of gears to transmit the most suitable torque for specific driving conditions is carried out using shift forks, they are driven by a selector control mechanism. The gear shift mechanism moves along and in the transverse direction using the gearshift lever. It can be located directly on the gearbox housing, or it can be taken out separately and fixed on the car body or sometimes on the steering column.

In these cases, a rocker design is used to drive the switching mechanism. The entire principle of operation of the gearbox is based only on gearing with helical gears, and they are lubricated transmission oil, which is poured into the gearbox housing.

The operating principle of a two-shaft gearbox is similar to a three-shaft design, with only one difference. The design does not have an intermediate shaft, and the primary and secondary shafts are located in parallel. And one more fundamental difference - rotation is transmitted by only one pair of gears, while in a three-shaft design, rotation is transmitted using a third gear on the intermediate shaft. Another design difference is that a two-shaft gearbox cannot have direct transmission. That is, the gear ratio is 1:1.

Reverse gear. which rotates the secondary shaft in the direction opposite to the rotation of the crankshaft, is carried out using a separate gear on its own shaft. The same reverse gear scheme is implemented in the three-shaft gearbox. Gears in a two-shaft gearbox are shifted using a rod rather than a fork. The rod pushes the desired gear, it engages with the pair and is fixed on the shaft with a special lock. In twin-shaft gearboxes, as a rule, the differential is arranged in the same housing with the gearbox.

In general terms, this is how a two-shaft and three-shaft type manual transmission works. Don't crunch your gears, and good luck to everyone on the road.