Transmission is an important unit in the device of the car and is designed to transfer engine power to the drive wheels. In the process of power transfer, in the form of torque, it is transformed (increase or decrease), change direction, etc. The second purpose of the gearbox is to turn off the torque from the transmission, with the exception of a manual gearbox. In this type of boxes, the torque is turned off using a separate unit - the clutch.
Consider below all the concepts of gearboxes, their main pros and cons, prospects.
There are main types of gearboxes:
Mechanical box (manual transmission)
Automatic transmission (automatic transmission)
Robotic box (RKPP)
Variable box (Variator)
The manual is controlled manually, this is an older type, but it has proven itself very well, especially for drivers who like to feel the full power of their iron horse. The natural disadvantage of such gearboxes is low efficiency, due to the friction of the gear teeth, the resistance of the gear oil.
On passenger cars, two main types of gearboxes are used: mechanical and automatic (hydromechanical). The manual transmission is controlled by the driver, including the desired gear of his choice (depending on the vehicle's driving mode). In a hydromechanical gearbox, the gears are switched automatically depending on the load on the engine (crankshaft speed).
Any operating principle transmission is based on a change in the speed of the driven gear when the number of teeth of the drive gear changes. With a decrease in the number of teeth of the drive gear, the driven gear will rotate at a lower frequency, with an increase, at a higher frequency. At the same time, when the number of teeth of the drive gear decreases, the torque on the driven gear increases.
Typically, passenger car transmissions have four or five pairs of gears with different gear ratios. Depending on their number, the gearbox is called a four- or five-speed. (Reverse gear is not included in this number, although it is mandatory in any gearbox.) The gear ratio from the lowest (first) gear to the highest (fourth or fifth) is gradually reduced. The gear ratio of the fourth gear in all boxes, as a rule, is equal to one. Such transmission is called direct.
First gear is designed for starting off and moving the car at the lowest speed. When accelerating to 10 ... 15 km / h, you can switch to second gear, then at a speed of 30 ... 40 km / h - to third and, finally, at a speed of 60 ... 70 km / h - to fourth gear. The Owner's Manual for a specific vehicle must indicate the maximum speed in each gear.
Upshifting (from lower to higher) should only be done sequentially. When decelerating and downshifting, some steps can be skipped if the speed of the vehicle allows. For example, after driving in a straight line at 60 km/h and decelerating to 20 km/h before turning, you can shift from fourth to second gear.
Recently, five-speed gearboxes have become increasingly common. The fifth gear in them is an overdrive gear (the gear ratio is less than one, for example, 0.8, i.e. the number of teeth of the driven gear is slightly less than the number of teeth of the drive gear). This transmission allows you to drive at a steady speed of over 80 km / h at a lower engine speed, for example, on a flat, straight highway, and the engine consumes less fuel.
In the gearboxes of modern passenger cars, all pairs of gears are in constant engagement, and for durable and quiet operation, the gear teeth are made with helical teeth. The synchronizer allows the driver to silently engage the desired gear.
The synchronizer includes a hub rigidly mounted on the secondary shaft, on the surface of which the teeth are made. A toothed clutch sliding along it is placed on the teeth of the hub. The device of the clutch allows, when it is turned on, to smoothly equalize the frequency of the switched gear with the speed of rotation of the driven shaft. An annular groove on the surface of the coupling serves for the fork, which is connected to the parts of the gear shift mechanism. The gears are freely placed on the secondary (driven) shaft. All of them are made as a single unit with gear rims having straight teeth.
To turn on the 1st gear, move the rear clutch back until it is connected to the ring gear of the largest gear on the driven shaft. In this case, the rotational force from the engine is transmitted to the output shaft through the gears.
To turn on the reverse gear, an intermediate gear is used. When reversing, the rotation from the input shaft to the secondary is transmitted through the intermediate shaft gear and the gear to the mobile gear, which is moved back to failure along the splines of the shaft. In this case, the secondary shaft reverses the direction of rotation.
Automatic transmission is also known and used for a long time in the automotive industry. Switching speed steps occurs in automatic mode, but the command to start moving or reversing requires a driver's command. Like the manual transmission, the machine has a low efficiency for the same reasons and due to the presence of planetary mechanisms in the box device.
Lovers of such boxes are, of course, our ladies. Many simply do not know that there used to be a third pedal - the clutch. The ladies can also be attributed to the American consumer, Americans very rarely buy cars with mechanics.
As mentioned above, manual transmission is the best option for a gearbox, and even a robotic gearbox is made on its basis, but with automatic control. Robot control can even adjust to your driving style. The disadvantages are the same as those of the mechanics, but there are much more pluses. By using two shafts, it was possible to increase the efficiency, reduce the overall dimensions, and increase the reliability of the box.
Automatic transmissions (ACP) are found mainly on foreign (especially American) cars, and from domestic ones - on some Volga cars. The main difference between an automatic transmission and a mechanical one is the transmission of torque from the engine to the transmission through the pressure of the fluid flow in the torque converter (there is no clutch mechanism).
The torque converter is one of the varieties of hydrodynamic transmission. It consists of pump and turbine wheels and a liquid-filled reactor placed between them. The pump wheel is rigidly connected to the flywheel and the drive shaft, and when the engine is running, it creates a powerful fluid flow that rotates the turbine wheel. From the blades of the turbine wheel, the liquid enters the reactor blades, resulting in a reactive force directed towards the rotation of the turbine wheel. Depending on the frequency of rotation of the engine crankshaft, the reactive force increases or decreases, and in the stepped mechanism (gearbox) connected to the torque converter by the driven shaft, automatic gear shifting is carried out - respectively, up or down (up or down).
The use of a torque converter allows you to start smoothly and smoothly accelerate under load, steplessly changing the speed of the car.
An automatic transmission car is definitely easier to drive than a manual car. However, such cars are usually more expensive, and automatic transmission repair in case of breakdown is more difficult.
Gear oil is used to lubricate the parts of a mechanical gearbox, a certain amount of which is poured into the gearbox and final drive housing. Gear oil reduces energy costs to overcome friction, reduces wear of parts, prevents overheating and corrosion. Passenger cars use gear oils of groups GL-4 and GL-5 (according to the international API classification).
They correspond to domestic oils of the TM-4 and TM-5 groups. Gear oils are divided into viscosity grades: 75W, 85W, 90 and 140 (according to SAE classification depending on the season) or 9; 12; 18 and 34 (according to the domestic classification). The higher the number, the higher the viscosity. These figures are included in the designation of the brand of oil. Imported all-weather oil 85W-90 of the GL-5 group corresponds to all-weather oil TM-5-18. For some vehicles, the manufacturer recommends using engine oil of a certain viscosity in the transmission units. A special fluid is used in the torque converters of automatic transmissions. In addition to its quantity (level) and quality (compliance with this automatic transmission model), the driver must also monitor its temperature during operation. The automatic transmission fluid cooling system is structurally integrated with the engine cooling system, so a car with an automatic transmission cannot be towed with the engine not running for longer than a certain time: the fluid, not receiving sufficient cooling, will overheat, and the automatic transmission parts may fail.
The transmission of any car is a system that performs the functions of converting, distributing and bringing torque from the engine to the drive wheels. The gearbox is the most important element of this system.
Gearbox: functions and main types
The gearbox of the car is designed to convert and distribute the engine torque for subsequent bringing it to the driving wheels, as well as to change the amount of tractive effort under various driving conditions of the vehicle. In addition, it is designed to ensure the disconnected operation of the drive wheels and the engine (for example, when the engine is warming up or running in neutral).
At the moment there are four main types of box:
- mechanical;
- robotic;
- automatic;
- variable speed drive.
Manual transmission ("mechanics", manual transmission) has the simplest principle of operation. It is a cylindrical gearbox, for which a manual gear shifting method is provided.
The main types of manual transmission
We focus on the "mechanics". This will be the most optimal, if only because knowledge of the manual transmission will allow, with certain skills and abilities, to carry out its ongoing maintenance and even repairs.
"Mechanics" is a manual gearbox. In other words, the principle of operation of mechanics is as follows: the engine torque changes in steps - pairs of gears interacting with each other. Each stage has a certain gear ratio that converts the rotation speed of the engine crankshaft and provides rotation with the required angular velocity.
The number of steps that a gearbox is equipped with is the basis for the classification of manual transmissions. So, allocate:
- four-stage;
- five-speed;
- six or more.
The most optimal option among specialists is a five-speed gearbox, which is the most common among “mechanics”. 
The second criterion for classifying a mechanical box is the number of shafts used in the conversion and distribution of engine torque. There are three-shaft gearboxes (used mainly on rear-wheel drive vehicles) and two-shaft gearboxes (used on front-wheel drive vehicles).
The device of a two-shaft gearbox and the principle of its operation
We confine ourselves to the analysis of the most common type of mechanical gearbox - two-shaft. The mechanical transmission device includes the following parts and assemblies:
- primary (or driving) shaft;
- input shaft gear block;
- secondary (or driven) shaft;
- block gears of the secondary shaft;
- gear shift mechanism;
- synchronizer clutches;
- crankcase;
- main gear;
- differential.
The functions of the input shaft are reduced to the transmission of engine torque (by connecting to the clutch). The block of gears of the primary shaft is rigidly fixed on the shaft.
The secondary shaft is parallel to the primary. Its gears, freely rotating on the shaft, are engaged with the gears of the input shaft. In addition, a gear is in a rigidly fixed state on the driven shaft - an element of the main gear.
The purpose of the main gear and differential is to transmit torque to the drive wheels of the vehicle. The shift mechanism provides the choice of the necessary gear in specific driving conditions of the car.
Despite the fact that the device of the box (two - and three-shaft) are different, the principle of their operation is the same. 
Neutral excludes the supply of torque from the engine to the wheels. Moving the lever (shifting) means moving the synchronizer clutch with a special fork. The clutch synchronizes the angular speeds of the output shaft and the corresponding gear. The clutch ring gear then engages the gear ring gear, which locks the output shaft gear on the shaft itself. As a result, the box transmits torque with a certain gear ratio from the car engine to the drive wheels.
The principle of operation of a manual gearbox when shifting gears is absolutely identical.
The main malfunctions of the manual transmission
Manual transmission malfunctions are determined by the features of its design and operation. The most common mechanical transmission technical problems are as follows.
1. Difficulty shifting (or engaging) gears.
The indicated malfunction is due to the failure of the gear shift mechanism, wear and tear of synchronizers or gears, insufficient level or low quality of gear oil in the crankcase.
2. Unintentional disengagement of gears.
This circumstance (colloquially referred to as “speed flies”) is determined by malfunctions of the locking device (for example, locking balls) and critical wear of synchronizers and gears.
3. Stable background noise during operation.
This error needs to be specified. Experts distinguish three of its manifestations:
- noise during operation of the box;
- noise during operation of only one particular gear;
- box noise in the neutral position of the control lever.
The general noise of the box is caused by wear or damage to bearings, gears, synchronizers, spline connections, as well as a low level of gear oil in the crankcase. Noise during operation of one of the gears is an indicator of wear or damage to specific gears and synchronizers. But the noise background in the "neutral" position most often indicates wear on the bearing of the drive (primary) shaft.
4. Gear oil leakage.
This gearbox problem is associated with an excess of lubricant in the gearbox or a general leak in the crankcase caused by damage to oil seals, seals, and loose covers.
Most often, the malfunctions described above associated with wear and damage to parts and assemblies are eliminated exclusively by their replacement. Moreover, the most preferable in this case is to contact a specialized car service.
Basics of operation and maintenance of manual transmission
Subject to the rules of operation, proper maintenance and service, the driver should not have problems with the car's gearbox. In this case, it works until the end of the life of the vehicle. 
During the operation of the box, it is necessary to constantly monitor the level of lubrication - gear oil - and maintain the required indicator, not allowing it to be exceeded or underestimated. In the first case, excessive pressure will be concentrated in the gearbox, in the second, proper lubrication of rubbing components and parts will not be provided, which will lead to a decrease in their life. In addition, an important preventive measure is periodic complete replacement of lubricant, which is carried out in accordance with the technical documentation of the vehicle. This principle of operation of the gearbox can be controlled by the driver independently, without the involvement of a specialist.
There are very frequent cases of mechanical failures of the box as a result of unreasonably aggressive and rough work of the driver with the gear lever. It is important to remember that switching gears is a change in the operating modes of the box (changing steps). A sharp and quick gear change can lead to a quick failure of the shift mechanism, synchronizers, and gear shafts.
And one more thing: it is important to control how the gearbox works. No one will ever replace the human factor: a driver who feels the non-standard operation of the checkpoint must either independently find and eliminate the cause of the malfunction, or (preferably) contact a service man at the service station.
The gearbox, or otherwise the transmission, transmits the rotational force - the so-called torque - from the car's engine to the wheels. At the same time, depending on the driving conditions of the car, it can transmit torque in whole or in part.
A car going uphill should use a lower gear than a car going down a flat freeway. A lower gear sends more torque to the wheels. And this is required when the car is moving slowly, because it is hard for her. Higher gears are suitable for faster vehicle movement.
There are manual transmissions, 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 again transfer its energy to the wheels. In an automatic transmission, the position of the gas pedal (accelerator) is correlated with the speed of the car, and the gear changes automatically if necessary.
Manual transmission control
The adjacent diagrams show how the shift lever can be used to shift from one gear to another. Depending on the gear set, different proportions of the torque passing through the gearbox (red lines with arrows) get to the wheels. Neutral gear. Engine power is not transferred to the wheels.
Neutral gear. Engine power is not transferred to the wheels.
First transfer. The largest gear of the drive shaft is connected to its pair on the driven shaft. The machine moves slowly, but can overcome difficult sections of the road.
Second transfer. The second pair of gears work together with the clutch mechanism. In this case, the speed of the car 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 at the wheels is less.
Fourth gear. The input and output shafts are connected directly (direct transmission) - the speed of the car is maximum, and the torque is the lowest.
Reverse.(5th gear in the picture) When the reverse gear is engaged, its drive gear "rotates the output (drive) shaft in the opposite direction.
Accelerator operation
The number of engine revolutions per minute depends on how much fuel flows from the carburetor into the cylinders. The movement of fuel is controlled by the carburetor throttle, and the operation of the throttle is controlled by the accelerator pedal, which is located on the floor in front of the driver.
When the driver presses the accelerator pedal with their foot, the throttle opens and more fuel enters the engine. If the driver releases the accelerator pedal, the damper is closed and the amount of incoming fuel is reduced. At the same time, both engine speed and vehicle speed decrease.
Automatic transmission
When an automatic transmission is used, the driver does not have a clutch pedal under his foot. Instead, a torque converter paired with a planetary gear (figure on the right and bottom) automatically disconnects the engine from the input shaft when, according to driving conditions, it is necessary to change gear.
And after the gear has changed, the drive shaft is connected again. As soon as the driver puts the control lever in the working position, the automatic transmission mechanism itself will select the desired gear in accordance with the driving conditions of the car at the moment.
24. Purpose, types, general arrangement and principle of operation of the gearbox
The concept of gear ratio.
gearbox is called a transmission mechanism that changes the ratio between the speeds of rotation of the crankshaft of the engine and the drive wheels when the car is moving. The gearbox is used to change the torque on the driving wheels of the car, long-term separation of the engine and transmission and reverse gear.
Changing the torque on the drive wheels and the speed of the vehicle is carried out by increasing or decreasing the gear ratio of the gearbox, which is the ratio of the speed of rotation of the input shaft to the speed of rotation of the driven shaft. The presence of a gearbox in the transmission allows you to increase the traction and speed properties, fuel efficiency and vehicle cross-country ability.
In step gearboxes, the gear ratio changes in steps and the traction force on the driving wheels of the car also changes in steps. In continuously variable gearboxes, the gear ratio and traction force on the drive wheels change smoothly, and with hydromechanical gearboxes, both smoothly and stepwise. In non-automatic transmissions, gear shifting is carried out manually by the driver using a shift lever located on the gearbox or on the steering column. In semi-automatic transmissions, the choice of the required gear is carried out by the driver, and the gear is engaged automatically. In automatic transmissions, gear shifting occurs automatically without the participation of the driver and depending on driving conditions. Most cars and trucks use stepped gearboxes, and hydromechanical gearboxes, consisting of a torque converter and a stepped manual gearbox, are becoming more common in cars and buses.
Gearbox requirements. In addition to the general requirements for the design of the car, the gearbox is subject to special requirements, according to which it must provide:
Optimum traction and speed properties and fuel efficiency of the car;
Quiet operation and gear shifting;
Ease and convenience of management;
High efficiency;
Possibility of power take-off to drive additional equipment.
A speed gearbox is a gear (gear) mechanism in which the gear ratio changes in steps. gear ratio called the ratio of the number of teeth of the wheel (the larger of the pair) to the number of teeth of the gear (the smaller of the pair), or the inverse ratio of their rotational frequencies. If several pairs of teeth are involved in the transmission, then the total gear ratio is equal to the product of their gear ratios. The gear ratios of the speed gearbox in all gears, except for the highest one, are greater than one. When these gears are engaged, the speed of rotation of the driven (secondary) shaft of the gearbox decreases and the transmitted engine torque increases by almost the same amount.
There are various types of manual gearboxes used in automobiles. Three-shaft gearboxes are most widely used in cars, trucks and buses. These gearboxes have three shafts - primary (drive), secondary (driven) and intermediate, on which gears of various gears are installed.
The design of a three-shaft gearbox and the number of its gears largely depend on the type of vehicle. However, four- and five-speed gearboxes have been widely used in cars, trucks and buses.
Mechanical, four-speed, three-way, constant mesh, synchromesh, and non-automatic (manual) transmission has four forward gears and one reverse gear. The gears of all gears (except reverse) are helical, which reduces noise during operation of the gearbox, and have constant meshing. Reverse gears are spur gears. Gears for forward movement are switched on with the help of synchronizers, and for movement in reverse - by moving the intermediate reverse gear. The gears are shifted using a lever that has three strokes forward and backward for shifting gears.
In cast aluminum crankcase 22 gearboxes on bearings installed primary (leading) 7, secondary (slave) 8 and intermediate 21 shafts. The input shaft is made as one piece with the gear 3, in constant engagement with the gear 23 intermediate shaft, which is a block of gears. Gears are freely mounted on the secondary shaft 5, 6 And 9 respectively III, II and I gears, which are in constant engagement with the corresponding gears of the intermediate shaft. Synchronizer hubs are also rigidly fixed on the secondary shaft. 4 and 7 and gear 10 reverse. Intermediate gear 7 reverse freely mounted on the axle 18. When you turn on I and II gears, the synchronizer 7 connects the gears, respectively 6 And 9 s gearbox output shaft. When 3rd and 4th gears are engaged, the synchronizer 4 connects respectively gear 5 and input shaft 1 with secondary shaft. Reverse is turned on with a fork 15 by engaging the gear 16 with gears 1 7 and 10. The gearbox housing is closed with covers 2, 14 And 19. Under the bottom 19 and back 14 cover gaskets installed.
The synchronizer consists of a hub 31, sliding clutch 32, blocking rings 30 and springs 29. The synchronizer hub is attached to the output shaft of the gearbox. It has external slots on which a sliding clutch is installed. 32 with internal conical surfaces. Blocking rings 30 have external conical surfaces and internal teeth with bevels. The blocking rings are constantly pressed by springs 29 to the sliding clutch 32. The operation of the synchronizer is based on the use of friction forces. Engaging the gear is possible only after preliminary equalization of the angular velocities of the secondary shaft and the gear of the gear being engaged due to friction between the conical surfaces of the sliding clutch 32 and blocking ring 30. After that, the teeth of the coupling engage with the ring gear of the synchronizer made on the gear; a freely rotating gear on the secondary shaft is connected to the secondary shaft by means of a synchronizer, and the gear is engaged. The gearshift mechanism includes a shift lever , sliders with forks, ball clamps and castle . Lever arm pressed by a spring to the spherical surface of the cover ball bearing. The figured end of the lever when shifting gears enters the grooves of the forks. The forks mounted on the sliders are included in the undercuts of the sliding sleeves of the synchronizers 4 and 7 and intermediate gear 16 reverse. ball detents hold the sliders in the neutral and on positions, and the lock eliminates the simultaneous inclusion of two gears. The lock consists of two blocking crackers and a pin between them. When moving the middle slider both crackers come out of its recesses and lock the extreme sliders , excluding their displacement. When moving one of the extreme sliders, the cracker comes out of its recess, blocks the middle slider and, acting through the pin on the other cracker, also locks the other extreme slider, which excludes the inclusion of two gears at the same time.
The gearbox is attached to the rear end of the clutch housing. Into it through a threaded hole with a plug pour transmission oil. The internal cavity of the gearbox through the breather communicates with the atmosphere. The gearbox oil is drained through a threaded hole with a plug located in the bottom cover .
Most internal combustion engines have one big drawback. This is a discrepancy between the speed of rotation of the flywheel with the speed of rotation of the wheels. Often, most power units rotate at speeds up to 6000, it is simply unacceptable to rotate the wheels at such speeds. For those who know the structure of the car, the gearbox is a familiar mechanism. For those who do not know, this article will clarify the situation.
In addition, the maximum torque in most units is possible only in a small interval of revolutions. It's somewhere in between the minimum RPM and the maximum RPM. The greatest power can be developed only 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 it works?
If we briefly talk about the principles of operation, then here several gears in the box housing can enter and leave engagement at the will of the driver. In this case, gears with different gear ratios are formed.
A manual transmission is always used and works in conjunction 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 device of a manual transmission does not provide for the possibility when a large torque passes through the transmission system at the time of a gear change.
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 by means of bearings. The gears are mounted directly on the shafts. The gearbox arrangement may be different, depending on the number of shafts. So, a two-shaft system and a three-shaft system are distinguished.
Three shaft systems
These gearboxes are used in the transmission of cars equipped with rear-wheel drive. Here you can highlight the presence of devices for synchronization, as well as special wheels that are tough on conventional gears. There is also a reverse gear for reversing.
The gearbox device implies the presence of special shafts. These are the primary, secondary shafts, as well as a special shaft between them.
So, the main, or primary, shaft through the clutch system works directly with the motor. The driven shaft works in tandem with the cardan. But the intermediate one is designed to transfer the rotational energy from the drive shaft to the driven one.
Transmission Design Features
In most box designs, both the input shaft and the secondary are mounted one behind the other. In this case, the driven one is supported on the basis of a bearing, which, in turn, is mounted in the tail section of the drive shaft. The mechanical transmission device 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 driving and driven. All these shafts are equipped with a block of gears. In order to reduce noise and vibration during the operation of this system, the teeth on the wheels are made oblique.
There is only one gear wheel on the drive shaft. It is hardwired. 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 able to move along the longitudinal axis. In order to enable transmission, they can be blocked using a blocking device. In this state, they will be able to receive rotational energy from the shaft.
Gears are located against each wheel of the primary and secondary shafts, which are rigidly mounted on the intermediate shaft. They are constantly engaged with other gears. The drive shaft is equipped with only one gear, the moment from the input shaft to the intermediate is always transmitted. The inclusion of a particular gear is due to the connection of a certain gear mounted on the driven roller.
How are gears shifted?
The gearbox device is not only a set of shafts and gears. These are also special couplings. They do not look like gears and have a different design. They are firmly attached to each shaft and are in rotation with it. They can move along the longitudinal axis.
On the side of the gears of the driven shaft, which are directed to the couplings, special rims or forks are installed. Other crowns are located directly on the couplings.
When the driver moves the lever and wants to select another gear, then through a special drive with the help of sliders, the forks are activated, which move the clutches longitudinally. A special locking system does not allow switching on 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.
Then the clutch is sent to the desired gear. Their crowns meet. The clutch rotates with its shaft all this time. It connects to the gear, thereby blocking it. Then they begin to rotate together, and the gearbox transmits rotation to the wheel drive.
Synchronizers
The gearbox device also includes special devices. With the principle of operation described above, the gearbox will work with noise, vibration and shock. Also, the driver will have to guess when the clutch and gear will work at the same speed. Otherwise, the desired transmission simply will not turn on.
Modern boxes do not use the usual and most simple couplings. In such models, so-called synchronizers are used. They are designed to equalize the speed of rotation of the gear and the clutch. They also prevent the clutch from blocking the wheel.
The device and principle of operation of the two-shaft type gearbox
There are all the same, already familiar, driven and drive shafts, but there is no intermediate one. These boxes are installed on front-wheel drive cars. The shafts rotate in parallel axes, and they are mounted one after the other. The torque is given from one of the gears to the driven gear fixed on the driven shaft with the help of a synchronizer. There is no possibility of direct transmission, and the principle of operation is the same as in the three-shaft system.
Advantages
Among the advantages are compact dimensions and high efficiency. This is due to the smaller number of gears. As a disadvantage, we can single out the impossibility of using direct transmission. And yet such a box can only be used with passenger cars due to difficulties with large gear ratios.
VAZ gearbox device
VAZ vehicles use five-speed manual gearboxes. Often the design is a two-shaft system. This system is also equipped with a differential. Drive gears from 1 to 4 gears are installed on the input shaft, and the 5th gear is removable. They are connected to driven gears.
The design of the switching system consists of a lever, a ball bearing, a system of rods, 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 unified as much as possible.
From mechanics to automatic
When the device and operation of the gearbox is more or less clear, you can consider the operation of an automatic transmission. It's much more interesting. Many beginners are sure that the machine is directly a box and a torque converter.
The torque converter is a separate system. It consists of two machines with blades. It is a centrifugal pump as well as turbines. Between these two machines is a reactor. This is a special guide. The pump wheel is rigidly fastened to the engine crankshaft. The turbine wheel is in rigid connection with the gearbox shaft. Depending on the mode in which the engine is operating, the reactor can either rotate or be blocked by a freewheel.
The automatic transmission device is a little more complicated. Energy is used to pump oil. A decent amount of it is eaten here. In addition, a lot of useful energy is also 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 transferred using oil flows. They are thrown to 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, it is possible to 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 device of an automatic transmission differs from the standard "mechanics" in that any gear can be engaged, and there will be no interruption in power flows. If one gear is turned off, the other is immediately turned on. In this case, the driver does not feel jerks. But this is not about sports boxes.
