Manual gearbox: operating principle. Purpose, principle of operation and design of the gearbox. Design of a manual gearbox What is the operation of a gearbox based on?

A car's manual transmission is designed to change torque and transmit it from the engine to the wheels. It disconnects the engine from the drive wheels of the car. Let's explain what a manual gearbox consists of - how it works.

• crankcase;
• primary, secondary and intermediate shafts with gears;
• additional shaft and gear reverse;
• synchronizers;
• gear shift mechanism with locking and locking devices;
• shift lever.

Scheme of work: 1 - input shaft; 2 - shift lever; 3 - switching mechanism; 4 - secondary shaft; 5 - drain plug; 6 - intermediate shaft; 7 - crankcase.
The crankcase contains the main components of the transmission. It is attached to the clutch housing, which is mounted on the engine. Because During operation, the gears experience heavy loads; they must be well lubricated. Therefore, the crankcase is filled with half its volume with transmission oil.

The shafts rotate in bearings installed in the crankcase. They have sets of gears with different numbers of teeth.

Synchronizers are necessary for smooth, silent and shock-free gear shifting by equalizing the angular speeds of rotating gears.

Switching mechanism serves to change gears in the box and is controlled by the driver using a lever from inside the car. In this case, the locking device does not allow two gears to engage simultaneously, and the locking device keeps them from turning off spontaneously.

Gearbox Requirements

• Ensuring the best traction and fuel-economic properties
• high efficiency
• ease of control
• shock-free switching and quiet operation
• inability to engage two gears or reverse at the same time when moving forward
• reliable retention of gears in the engaged position
• simplicity of design and low cost, small size and weight
• ease of maintenance and repair

Ease of control depends on the gear shift method and the type of drive. Gears are switched using movable gears, gear couplings, synchronizers, friction or electromagnetic devices. For shockless shifting, synchronizers are installed, which complicate the design and also increase the size and weight of the transmission. Therefore, the most widespread are those in which higher gears are switched by synchronizers, and lower ones by gear couplings.

How do gears work?

a) Gear ratio of one pair of gears
Let's take two gears and count the number of teeth. The first gear has 20 teeth, and the second 40. This means that with two revolutions of the first gear, the second will make only one revolution (gear ratio is 2).

b) Gear ratio of two gears
In the picture b) The first gear (“A”) has 20 teeth, the second (“B”) has 40, the third (“C”) has 20, and the fourth (“D”) has 40. The rest is simple arithmetic. The input shaft and gear “A” rotate at 2000 rpm. Gear “B” rotates 2 times slower, i.e. it has 1000 rpm, and because gears “B” and “C” are fixed on the same shaft, then the third gear makes 1000 rpm. Then gear “G” will rotate 2 times slower - 500 rpm. From the engine, 2000 rpm comes to the input shaft, and 500 rpm comes out. On the intermediate shaft at this time - 1000 rpm.

In this example, the gear ratio of the first pair of gears is two, and the second pair of gears is also two. The total gear ratio of this scheme is 2x2=4. That is, the number of revolutions on the secondary shaft decreases by 4 times compared to the primary one. Please note that if we disengage gears “B” and “G”, the secondary shaft will not rotate. At the same time, the transmission of torque to the drive wheels of the car stops, which corresponds to neutral gear.

Reverse gear, i.e. rotation of the secondary shaft in the other direction, is provided by an additional fourth shaft with a reverse gear. An additional shaft is needed to get an odd number of pairs of gears, then the torque changes direction:

Torque transmission diagram when reverse gear is engaged: 1 - input shaft; 2 - input shaft gear; 3 - intermediate shaft; 4 - gear and reverse gear shaft; 5 - secondary shaft.

Gear ratios

First and reverse gears are the “strongest”. It is not difficult for the engine to turn the wheels, but in this case the car moves slowly. And when driving uphill in the “nimble” fifth and fourth gears, the engine does not have enough strength. Therefore, you have to switch to lower, but “strong” gears.

First gear is required to start moving so that the engine can move a heavy machine. Next, having increased the speed and made some reserve of inertia, you can switch to second gear, weaker but faster, then to third and so on. The usual driving mode is fourth (in the city) or fifth (on the highway) - they are the fastest and most economical.

What types of malfunctions occur?

The shift lever is moved with a calm, smooth movement, with micro-pauses in the neutral position so that the synchronizers are activated, protecting the gears from damage. If you handle it correctly and periodically change the oil in the “box,” it will not break until the end of its service life.

Operating noise, which depends mainly on the type of gears installed, is significantly reduced when straight-cut gears are replaced with helical ones. Proper work also depends on service on time.

Until recently, cars with a manual transmission, abbreviated as manual transmission, made up the absolute majority among other vehicles with various types.

Moreover, a mechanical (manual) gearbox remains a fairly common device today for changing and transmitting engine torque. Next, we will talk about how the “mechanics” are structured and work, what the design of a gearbox of this type looks like, as well as what advantages and disadvantages this solution has.

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Manual transmission diagram and features

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

Let's move on. The manual transmission is stepped, that is, the torque changes in steps. Many car enthusiasts know that a gearbox actually has gears and shafts, but not everyone understands how the unit works.

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

The gear ratio is the ratio of the number of teeth on the driven gear to the number of teeth on the drive gear. In this case, different gearbox stages receive different gear ratios. Lowest level ( low gear) has the largest gear ratio, and the highest gear (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, etc.) Note that the vast majority of cars today are equipped with five-speed gearbox gears, manual transmissions with 6 or more steps are less common, and the previously quite common 4-speed manual transmissions have gradually faded into the background.

Mechanical transmission device

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

• three-shaft gearboxes;
• double shaft boxes;

For cars with rear wheel drive Usually a three-shaft manual transmission is installed, while a two-shaft gearbox is installed on front-wheel drive passenger cars. In this case, the design of manual transmissions of both the first and second types may differ markedly.

Let's start with a three-shaft manual transmission. This box consists of:

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

Gears with synchronizers are installed on the shafts. Also included in the gearbox device is a gear shift mechanism. These components are located in the gearbox housing, which is also called the gearbox housing.

The job of the drive shaft is to create a connection with the clutch. The drive shaft has splines for the clutch driven disc. As for the torque, the specified moment from the drive shaft is transmitted through the gear, which is in rigid mesh with it.

Regarding the operation of the intermediate shaft, this shaft is located parallel to the input shaft of the gearbox, and a group of gears is installed on it, which is in rigid mesh. In turn, the driven shaft is mounted on the same axis with the drive shaft.

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

Synchronizers (synchronizer clutches) are installed between the driven shaft gears. Their task is to align the angular speeds of the driven shaft gears with the angular speed of the shaft itself through friction.

The 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 presence of a spline connection. Modern gearboxes have synchronizer clutches in all gears.

If we consider the gear shift mechanism on three-shaft gearboxes, this mechanism is often installed on the unit housing. The design includes a control lever, sliders and forks.

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

• To understand how a three-shaft type mechanical (manual) gearbox works, let's take a general look at the principle of its operation. When the gearshift lever is in neutral, no torque is transmitted from the engine to the vehicle's drive wheels.

After the driver moves the lever, the fork moves the synchronizer clutch of a particular gear. The synchronizer will then equalize the angular speeds of the desired gear and the driven shaft. The clutch ring gear will then engage with a similar gear ring, locking the gear onto the driven shaft.

Let us also add that the reverse gear of the vehicle is ensured by the reverse gear of the gearbox. In this case, the reverse idler gear, mounted on a separate axle, allows you to change the direction of rotation.

Twin-shaft manual gearbox: design and principle of operation

Having figured out what a gearbox with three shafts consists of, let's move on to two-shaft gearboxes. This type of gearbox has two shafts: primary and secondary. The primary shaft is driving, the secondary shaft is driven. Gears and synchronizers are attached to the shafts. Also in the gearbox housing is the main gear and differential.

The drive shaft is responsible for connecting to the clutch, and there is also a gear block on the shaft in rigid engagement with the shaft. The driven shaft is located parallel to the drive shaft, while the gears of the driven shaft are in constant mesh with the gears of the drive 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 driven shaft gears themselves. Let us add that in order to reduce the size of the gearbox, as well as increase the number of gears, in modern gearboxes, instead of one driven shaft, 2 or even 3 shafts can often be installed.

A main gear gear is rigidly fixed to each such shaft, and such a gear is rigidly engaged 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, transmits torque from the secondary shaft to the drive wheels. At the same time, the differential can also provide such wheel rotation when the drive wheels rotate at different angular speeds.

As for the gear shift mechanism, on twin-shaft gearboxes it is located separately, that is, outside the housing. The box is connected to the switching mechanism by cables or special rods. The most common connection is using cables.

The shift mechanism of the 2-shaft box itself has a lever that is connected by cables to the selection lever and the gear shift 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 gearbox, it is similar to the principle of a three-shaft gearbox. The differences lie in how the gear shift mechanism works. In a nutshell, the lever can carry out both longitudinal and transverse movements relative to the axis of the car. During lateral movement, a gear is selected, since the force is applied to the gear selection cable, which affects the gear selection lever.

Next, the lever moves longitudinally, and the force goes to the gear shift cable. The corresponding lever horizontally moves the rod with the 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 locking devices that prevent two gears from being engaged at the same time or a gear being switched off unexpectedly.

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

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 engine internal combustion of any car is capable of operating only in some limited, and rather small, rev range. And the frequency of rotation of the wheels - from starting from a standstill to driving at 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, to apply more power to its wheels. That is, at low speeds you need high engine speeds.

On the contrary, when an accelerating car moves uniformly on a flat road, its speed is high, and high power and high speed an engine is no longer required - to maintain the desired speed, both low power and low revs. As the speed increases, the aerodynamic resistance to engine movement also increases, 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. One of the pioneers of the world automobile industry, the German engineer Karl Benz, was convinced of this on his first long (80 km) trip in a car of his 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 engage 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 type of planetary gearbox that was equipped with the first mass production Ford A cars.

No less important a technical solution than the invention of the box on gears of various diameters was the invention of the synchronizer, which was made in 1928 by Charles Ketering from General Motors. 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 automatic cars.

A manual transmission consists of a set of helical gears 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.

From a technical point of view, a manual transmission is an enclosed gearbox. The working elements of its design are gears - gears that alternately come into engagement, changing the revolutions of the input and output shafts, as well as their frequency. Switching 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 for the production of gearboxes require the presence of such synchronizers in all gears for forward movement.

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 twin-shaft layout of the 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 rare cases, on modern cars Four-shaft gearboxes can also be used. But according to the principle of their operation, they also correspond to two-shaft ones - without an intermediate shaft, with rotation transmitted from the primary shaft directly to the secondary ones. Most often, this manual gearboxes with 6 forward gears. In them, torque is transmitted from the input shaft to the main gear through the first, second and third secondary shafts, the end gears of which are constantly meshed with the main 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 reverse side. 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 low gears even with high speed engine, 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 drive at low speeds. But it can move at high speeds, up to the maximum provided, at medium engine speeds.

The vast majority of modern manual transmissions have gears with helical teeth, 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, in order to engage a higher gear without shock, 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 switch to a lower gear, it was necessary to revise the throttle 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, modern passenger car these “skills from the past” can also come in handy. 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 fails.

The gearbox, or transmission in other words, transmits the rotational force - the so-called torque - from the car engine to the wheels. Moreover, depending on the driving conditions of the vehicle, it can transmit torque completely or partially.

A car going uphill should be in a lower gear than a car going down a flat highway. With a lower gear, more torque is transmitted to the wheels. And this is required when the car is moving slowly because it is hard. Higher gears are suitable for driving the car faster.

There are gearboxes with manual control, but there are also automatic ones. To change gear in a manual transmission, the driver first presses the clutch pedal (picture on the left). In this case, the engine is disconnected from the gearbox. Then the driver moves the control lever to another gear and releases the clutch pedal. The engine is reconnected to the gearbox and can once again transfer its energy to the wheels. In an automatic transmission, the position of the gas (accelerator) pedal is correlated with the speed of the vehicle, and the gear is automatically changed if necessary.

Manual transmission control

The adjacent diagrams show how the control lever can be used to change from one gear to another. Depending on the gear installed, different shares of torque, passing through the gearbox (red lines with arrows), reach the wheels. Neutral gear. Engine energy is not transferred to the wheels.

Neutral gear. Engine energy is not transferred to the wheels.

First transfer. The largest gear on the drive shaft is connected to its pair on the driven shaft. The car moves slowly, but can overcome difficult sections of the road.

Second gear. The second pair of gears works together with the clutch mechanism. In this case, the vehicle speed is usually from 15 to 25 miles per hour.

Third gear. The third pair of gears works together with the clutch mechanism. The speed of the car is even greater, and the torque on the wheels is less.

Fourth gear. The input and output shafts are connected directly (direct transmission) - the vehicle speed is maximum and the torque is the lowest.

Reverse (5th gear in the picture) When reverse gear is engaged, its drive gear rotates the output (drive) shaft in the opposite direction.

Accelerator operation

The engine speed per minute depends on how much fuel flows from the carburetor into the cylinders. The movement of fuel is regulated by the carburetor throttle valve, and the operation of the throttle valve is controlled using the accelerator pedal, which is located on the floor in front of the driver.

When the driver presses the accelerator pedal with his foot, throttle valve opens and more fuel enters the engine. If the driver releases the accelerator pedal, the throttle closes and the amount of incoming fuel decreases. At the same time, both engine speed and vehicle speed decrease.

Automatic transmission

When to use automatic transmission, the driver does not have a clutch pedal under his foot. Instead, a torque converter paired with a planetary gear (picture on the right and below) automatically disconnects the engine from the drive shaft when driving conditions require changing to another gear.

And after the gear has changed, the drive shaft is reconnected. Once the driver places the control lever in working position, and mechanism automatic transmission gears will select the desired gear in accordance with the vehicle's driving conditions at the moment.

Most internal combustion engines have one big drawback. This is a discrepancy between the speed of rotation of the flywheel and the speed of rotation of the wheels. Often the majority power units rotates at speeds up to 6000, spinning the wheels at such speeds is simply unacceptable. For those who know the structure of a car, the gearbox is a familiar mechanism. For those who don't know, this article will clear things up.

In addition, the maximum torque in most units is possible only in a small range of revolutions. This is somewhere in the middle of the minimum number of revolutions and the maximum. Highest power can only be developed at maximum flywheel speed.

For example, the VAZ-2106 engine produces performance indicators of 800-5400 rpm. But the maximum level of torque appears at medium speeds. In order for the engine to operate in optimal modes under various conditions, transmission systems are used. In cars, a manual transmission is used as a transmission system. Let's look at the purpose and design of the gearbox.

How does this work?

If we briefly talk about the principles of operation, here several gears in the box body can engage and disengage at the will of the driver. In this case, gears with different gear ratios are formed.

A manual transmission is always used and works together with the clutch system. This is a shutdown of the internal combustion engine and transmission. You need to turn off the engine when changing gears. The design of a manual transmission does not provide for the possibility of a large torque passing through the transmission system at the moment of changing gears.

Shafts and gears

Traditional manual transmissions are a specific set of shafts that are mounted in a housing or crankcase. These shafts rotate around their axes through bearings. The gears are mounted directly on the shafts. The design of the gearbox may be different, depending on the number of shafts. Thus, a distinction is made between a two-shaft system and a three-shaft system.

Three-shaft systems

These gearboxes are used as part of car transmissions equipped with rear-wheel drive. Here we can highlight the presence of synchronization devices, as well as special wheels that are rigid in normal gears. There is also a reversible gear for reversing.

The gearbox design requires special shafts. These are the primary and secondary shafts, as well as a special shaft between them.

So, the main, or primary, shaft works directly with the engine through the clutch system. The driven shaft works in tandem with the cardan. But the intermediate one is designed to transfer rotational energy from the drive shaft to the driven one.

Transmission design features

In most box designs, both the primary and secondary shafts are mounted one behind the other. In this case, the driven one has a support based on a bearing, which, in turn, is mounted in the tail part of the drive shaft. The design of a manual transmission does not provide for any rigid connection between these shafts. They can work freely independently of each other.

As for the intermediate shaft, it is located in most designs between the drive and driven. All these shafts are equipped with a gear block. In order to reduce noise and vibration during operation of this system, the teeth on the wheels are made oblique.

There is only one gear on the drive shaft. It is mounted rigidly. It is responsible for transmitting torque to the intermediate shaft. The secondary, or driven, shaft is equipped with a block of gears that can rotate freely, but they are not capable of moving along the longitudinal axis. In order to engage the transmission, they can be blocked using a locking device. In this state, they will be able to receive rotational energy from the shaft.

Opposite each wheel of the primary and secondary shafts are gears that are rigidly mounted on the intermediate shaft. They are in mesh with other gears constantly. The drive shaft is equipped with only one gear; torque is always transmitted from the input shaft to the intermediate shaft. The inclusion of one or another gear occurs due to the connection of a specific gear mounted on the driven shaft.

How are gears changed?

The gearbox design is not just a set of shafts and gears. These are also special couplings. They are not like gears and have a different design. They are each firmly attached to its own shaft and rotate with it. They can move along the longitudinal axis.

On the side of the driven shaft gears, which are directed towards the couplings, special rings or forks are installed. Other crowns are located directly on the couplings.

When the driver moves the lever and wants to select another gear, the forks are activated through a special drive using sliders, which move the clutches longitudinally. A special locking system does not allow you to engage several gears at once. This is quite possible if the lever included two sliders. The locking mechanism locks the sliders in a neutral position at the moment when the third slider moves. This prevents the operation of two gears at the same time.

The clutch is then directed to the desired gear. Their crowns meet. All this time the coupling rotates together with its shaft. It connects to the gear, thereby blocking it. Then they begin to rotate together, and the gearbox transmits the rotation to the wheel drive.

Synchronizers

The gearbox design also includes special devices. With the operating principle described above, the gearbox will operate with noise, vibration and shock. Also, the driver will have to guess when the clutch and gear will operate at the same speed. Otherwise, the desired gear simply will not turn on.

Modern boxes do not use the usual and simplest couplings. In such models, so-called synchronizers are used. They are designed to equalize the rotation speed of the gear and clutch. They also prevent the clutch from locking the wheel.

Design and principle of operation of a two-shaft type gearbox

There are the same, already familiar, driven and drive shafts, but the intermediate one is missing. These boxes are installed on front-wheel drive cars. The shafts rotate in parallel axes, and they are mounted one after another. The rotational moment is transmitted from one of the gears to the driven gear fixed on the driven shaft using a synchronizer. There is no possibility of direct transmission, and the operating principle is the same as in the three-shaft system.

Advantages

Among the advantages are compact dimensions and high efficiency. This is achieved thanks to fewer gears. The disadvantage is the inability to use direct transmission. And such a box can only be used with passenger cars due to difficulties with large gear ratios.

VAZ gearbox device

VAZ cars use five-speed manual transmissions. Often the design is a two-shaft system. This system is also equipped with a differential. Drive gears from 1st to 4th gears are installed on the input shaft, and the 5th gear is removable. They are connected to the driven gears.

The design of the shift system consists of a lever, a ball joint, a rod system, and a mechanism for selecting the required gear.

In general, most models are equipped with just such a box. It is a modernized version of the 4-speed model, and the parts from there are as unified as possible.

From manual to automatic

When the structure and operation of the gearbox are more or less clear, we can consider the operation of an automatic transmission. This is much more interesting. Many beginners are sure that an automatic machine is just a box and a torque converter.

The torque converter is a separate system. It consists of two machines with blades. This is a centrifugal pump and also a turbine. Between these two machines there is a reactor. This is a special guiding device. The pump wheel is rigidly attached to the crankshaft of the internal combustion engine. The turbine wheel is in rigid connection with the gearbox shaft. Depending on the mode in which the engine operates, the reactor can either rotate or be blocked by the overrunning clutch.

The automatic transmission is a little more complicated. Energy is spent pumping oil. A decent amount of it is eaten here. In addition, a lot of useful energy is consumed by the operation of the pump, which creates pressure in the oil channels. In these boxes the efficiency is lower than in mechanics.

The rotational energy is transmitted using oil flows. They are thrown onto the turbine by a pump. There are gaps between the pump and the turbine, and the blades have a special geometry that improves fluid circulation. Since there is no rigid connection with the engine and gearbox, you can stop the engine even with the gear engaged.

Planetary gears

If you rotate some elements, but at the same time fix others, then you can change the gear ratios. Planetary systems receive rotation from the torque converter shaft.

The design of an automatic transmission differs from a standard “mechanics” in that any gear can be engaged without any interruption in the power flow. If one gear is switched off, the other is immediately switched on. At the same time, the driver does not feel jerks. But this is not about sports boxes.