Manual transmission - time-tested reliability. How a manual transmission (manual transmission) works

mechanical box(switching) gear(Manual transmission or manual transmission) - a type of gearbox, a mechanism designed for a stepwise change in gear ratio, in which the choice of gear is carried out by the operator (driver) manually. It is named so because all of its main functionality is implemented solely by mechanical devices, without the use of hydraulic or electrical elements (as opposed to hydromechanical or electromechanical transmissions, which contain in their design, respectively, hydraulic and electrical elements).

Stepped simple gearboxes are widely used in vehicle transmissions, as they are simple in design and reliable in operation. The following requirements are imposed on gearboxes of this type:

• high traction and dynamic qualities of the vehicle
• high strength, rigidity, reliability and durability
• high efficiency, especially in the most used gears
• ease of control and quiet operation
• reliable fixation of the engaged and disengaged gears, preventing the simultaneous engagement of two gears
• small size and weight

These requirements determine the rational design of the gearbox and its individual parts.

Most of the wheeled vehicles studied are fitted with five-speed three-way simple gearboxes (five forward and one reverse). The number of “moves” of the gearbox corresponds to the number of moving elements with which the inclusion of certain gears is carried out.

The five-speed gearbox has 3 shafts:

• leading 7, connected by means of a clutch to the crankshaft of the engine
• driven 5, mounted coaxially with the drive shaft 7 and connected to the driveline
• intermediate shaft 6 with gears attached to it

The shafts are mounted on rolling bearings in the crankcase, which simultaneously serves as an oil reservoir, with filling, control and drain holes, as well as a ventilation device. An axle is fixed in the crankcase with a block of 7 gears ZX installed on it on bearings. The gear 17 is made integral with the drive shaft and is in constant engagement with the corresponding gear 16 of the intermediate shaft, as a result of which the intermediate shaft receives rotation from the drive shaft with a constant gear ratio, which is determined by the ratio of the number of teeth of the driven gear to the number of teeth of the drive. The gears of the driven shaft (except for the gears of the 1st gear and ZX) are in constant engagement with the corresponding gears of the intermediate shaft, but are freely installed on the driven shaft (they can rotate relative to the shaft, but not move along it). Therefore, although the intermediate shaft will rotate when the engine is running and the clutch is engaged, rotation will not be transmitted to the driven shaft, and therefore to the driving wheels of the propulsion unit (neutral position).

Rice. Diagram of a five-speed gearbox

The gears are switched on by two synchronizers - 2 and 3 and gear 4 of the 1st gear and ZX, which are mounted on the driven shaft on splines and can move along the shaft. The gear change mechanism comprises a control lever, rollers (rods) with forks moving synchronizers and carriage 4, latches and a safety locking device installed in the gearbox cover. Synchronizers have gear rims, which, when the gears are engaged, engage with the corresponding gear rims of constant mesh gears, which ensures the transmission of torque to the driven shaft and further to the driving wheels of the propulsion unit. The gear ratio between the intermediate and driven shafts is determined by the ratio of the number of teeth of the driven shaft gear to the number of teeth of the intermediate shaft gear. The gear ratio between the drive and driven shafts, i.e., the total gear ratio of the gearbox is the product of two gear ratios, one of which is between the drive and intermediate shafts, and the other between the intermediate and driven shafts.

The greater the gear ratio of the gearbox, the greater, with the same engine torque, the torque transmitted to the drive wheels, and the speed of the vehicle is correspondingly lower. In 1st gear, when the gear ratio is the largest, the vehicle is usually pulled off and the initial acceleration is carried out, as well as movement in particularly difficult conditions. The inclusion of 1st gear is ensured by moving gear 4 forward and engaging it with gear 8 of the intermediate shaft. As driving conditions improve, higher gears with smaller gear ratios are switched on, when a significant increase in traction force on the drive wheels is not required, and the speed of the vehicle increases.

The highest gear in the above diagram is the V gear, which is obtained by connecting the drive 1 and driven 5 shafts using the gear rims of the drive shaft and synchronizer 2; the gear ratio in this case is equal to one (direct transmission).

When the vehicle is moving in direct gear, the intermediate shaft of the gearbox rotates idly.

Reverse is provided by moving gear 4 back and engaging it with one gear of block 7 3X. The other gear of the block is in constant engagement with the gear 11, rigidly connected (fixed with a key) with the intermediate shaft.

Torque is transmitted from the drive shaft to the driven shaft through the following parts:

• when turning on the 1st gear - through gears 16, 17, 8 and 4
• II - through gears 16, 17, 9, 10 and synchronizer 3
• III - through gears 16,17, 12, 13 and synchronizer 3
• VI - through gears 16,17,14, 15 and synchronizer 2
• V - through gear 16 and synchronizer 2
• ZX - through gears 16, 17, 11, gear block 7 and gear 4

For smoother engagement and quieter operation, constant mesh gears are usually made helical. The angles and direction of inclination of the teeth on different pairs of gears are selected so that the axial forces on the shafts are the smallest. These axial forces are usually taken up by a deep groove ball bearing mounted at one end of the shaft. The other end of the shaft rests on a cylindrical roller bearing. This prevents the occurrence of additional stresses in the bearings as a result of thermal elongation of the shafts. The bearing seats are closed with covers with sealing gaskets. In the event that the end of the shaft comes out, seals are installed in the covers to prevent leakage of lubricant. This is also facilitated by oil-squeezing grooves on the shafts.

Lubrication of parts in the gearbox is carried out by spraying when the gears rotate or using an oil pump. Special gear oils are used for lubrication.

The gearbox is usually attached to the clutch housing and mounted with the engine on elastic mounts on the frame.

For example, the figure shows a longitudinal section of the gearbox of a KamAZ car.

Recently, there has been a tendency to install heavy-duty vehicles designed for difficult working conditions with an additional gearbox - reducing or accelerating (in some cases both at the same time). The presence of a reduction additional gearbox, usually installed behind the main one in the same crankcase, allows you to increase the total gear ratio between the engine and the drive wheels when driving in all gears in the main gearbox. An accelerating additional gearbox, usually installed in front of the main one in the same crankcase, allows you to increase the speed of the vehicle and reduce the torque on the shafts of the main gearbox. In addition, 2 intermediate shafts are installed in the main gearbox, and the gears of constant meshing are made spur, which makes it possible to reduce the size and weight of the gearbox.

Rice. Gearbox (longitudinal section) of a KamAZ car:
1 - drive shaft; 2 - cover of the rear bearing of the drive shaft; 3 - adjusting gasket; 4 - lever rod; 5 - rod support; 6 - spring; 7 - gear lever support; 8 - axis of the gear block ZX; 9 - gear block ZX; 10 - roller bearing; 11 - top cover; 12 - cover of the rear bearing of the driven shaft; 13 - rear ball bearing of the driven shaft; 14 - bushing; 15 - flange for fastening the cardan shaft; 16 - bearing cover; 17- spherical roller bearing; 18 - intermediate shaft; 19 - gearbox housing; 20 - driven shaft; 21 - cover of the front bearing of the intermediate shaft; 22 - clutch housing; 23 - clutch release fork; 24 - clutch release fork shaft; 25 - clutch release clutch

Due to the widespread use of automatic transmissions, more and more novice drivers prefer to learn on such cars. But a real driver must be able to handle a vehicle with any transmission, so
learn better on a car with a manual transmission. In addition, a manual gearbox has a number of advantages over an “automatic” one - it allows you to gain more control over the machine, spend less fuel in operation, and thanks to a simpler
design, it is cheaper both to purchase and to maintain. The only negative is that shifting gears on a manual gearbox may seem difficult for a beginner, but this will certainly pass with experience.

Before starting the practice, it is necessary to have some knowledge about the mechanical box. Most manual transmissions have 4 or 5 gears and one reverse, there is still neutral, when turned on, torque will not be transmitted to the wheels. From the neutral position, you can shift to any gear, including reverse. Be sure to learn the location of the gears so that you do not have to look at the gearshift lever while driving. 1st gear is used to a greater extent for starting off or when parking the car. You need to be careful with the rear - it has a greater speed range than the first, and with prolonged use it can damage the box.

And so, to start moving, you need to fully depress the clutch pedal and turn on the 1st gear, then, slowly releasing the clutch pedal, also gently press the gas pedal. At some point, you will feel how the car starts to move, hold the clutch in place for a while, then slowly release it completely. Having dispersed the car to a speed of 20-25 km / h, you need to switch to the second one, then release the gas pedal, depress the clutch all the way, turn on the second one and release the clutch. The transition to the third and higher speeds is carried out according to the same scheme. Do not jump gears: if the speed is insufficient, then the engine may not be able to cope - stall or simply start to slow down. The change to the next gear is made approximately every 25 km / h, but it costs
keep in mind that shift ranges for different cars may be different - they depend on engine power and gear ratios. Having gained a little experience, it will be possible to learn how to shift gears in time, focusing on
engine sound.

To switch to a lower speed - release the gas pedal and press the brake until the car slows down to the desired speed, then depress the clutch and switch to the desired one, release the clutch and press the gas pedal.
When lowering, always reduce the speed of the car - if you turn on a low gear at high speed, the car will brake sharply and may go into a skid. Also, when shifting gears, be sure to fully squeeze
clutch - otherwise you will hear a characteristic rattle in the box, and over time it will completely fail.

Knowing how to switch gears on a mechanical box, you can begin to practice. You need to understand that at first you may not succeed in many things, for example, smoothly release the clutch and switch to the right gear in time.
The most difficult thing at first will be a smooth start, so it's worth spending enough time training somewhere in a free area.

Gear shifting is a device that every car with an internal combustion engine needs. The need for this mechanism is due to the fact that any engine has a rather narrow speed range, where torque and power reach their maximum. And, in addition, each engine has a so-called “red zone” - a speed limit that must not be exceeded in order to avoid engine breakdowns.

This article will be completely devoted to the subject of the checkpoint, namely, its mechanical variety (manual transmission). After all, both an “experienced” driver and a novice motorist need to know the device of a manual gearbox and its principle of operation. Also, the article will present the graphic diagrams of the manual transmission, consider its main malfunctions and give advice on the proper operation of this vital mechanism for the car.

Types of gearboxes

In addition to mechanical, there are other types of gearboxes - CVT, and automatic.

The CVT gearbox is stepless. The most important parts of the variator are the sliding pulleys (there are two of them) and the belt that connects them. The connecting belt in a section has the form of a trapezoid. The main advantage of the variator is the constant operation of the car engine in optimal mode. There are also additional benefits, which include dynamism of acceleration, smoothness of movement and economy. In comparison with the "automatic" (, automatic transmission), the variator has a very simple design. But if we compare it with a manual gearbox, then the variator is still inferior to it in terms of dynamics and efficiency.

In addition, a CVT gearbox is almost impossible to combine with a powerful motor, since the fragility of the belt will not allow this. Maintaining and repairing the variator is quite an expensive pleasure, it will be easier and cheaper to replace the gearbox. And one more minus is the need for additional mechanisms for reversing and starting off.

A robotic gearbox is almost no different from a mechanical one - the torque is also transmitted from the engine to the transmission using the classic “dry” single-plate clutch. But still there is such a nuance: in the robotic box, the processes of gear shifting and on / off are automated. clutch. Therefore, the "robot" is able to greatly simplify the process of driving a vehicle - there is no need to manually and, losing precious time, think about which gear to turn on at a given moment. Also, to the advantages of the “robot” box, you can add its relative cheapness, efficiency and low weight.

However, there are also disadvantages. The robotic gearbox does not work too smoothly, and gear shifting occurs with a significant delay. In addition, at high speeds, the “robot” can react to switching with jerks and jerks. Manual mode will not help here, since the same electronics “commands” the clutch. If we compare a robotic box even with a simple automatic transmission, then the clarity of the “robot” switching is much inferior to the “automatic”. It should also be remembered that when starting to move, a car with a robotic box makes a small rollback. Based on all these disadvantages, manual transmission is traditionally put on the most "budget" car models.

Manual transmission device

Now let's move on to our "hero of the occasion", to whom this material is dedicated - to. As you know, a manual transmission is a mechanism that transmits, converts and changes the direction of torque from the engine flywheel. In the "mechanics" the steps are switched mechanically, respectively - by moving the gear lever. Torque is first transmitted to the output shaft, and then to the wheel drive.

What is meant by the term "step transmission"? Traditionally, it determines a stable transmission coefficient (the so-called gear ratio) between the interacting gears of the shafts - the driving and the driven. This "mechanic" differs from, for example, a variator, where the mentioned coefficient is not tied to the gear ratio and is floating. In other words, the ratio of the number of teeth on the driven gear to the number of teeth on the drive gear gives the gear ratio. These numbers differ at different stages of the checkpoint. The largest gear ratio is obtained at the lowest stage, and the smallest, on the contrary, at the highest.

In general, the principle of operation of a manual transmission is quite simple, and the set of its parts is small.

A manual transmission can be called relatively uncomplicated. The manual transmission package includes:

• shafts with gears (primary, intermediate and secondary);
• additional shaft with reverse gears;
• crankcase;
• synchronizers;
• directly the gearshift mechanism, equipped with devices for blocking and locks;
• shift lever.

Bearings are installed in the crankcase, in which the gearbox shafts rotate. The shafts are equipped with sets of gears with different numbers of teeth. For noiselessness and smooth gear shifting, synchronizers are used - they equalize the angular speeds of the gears during their rotation. The operation of the gear shift mechanism is to change gears - it is controlled by the driver using a lever. The locking device allows you to keep the transmission from unwanted self-shutdown. The locking device is designed to avoid switching on two gears at the same time.

Stages and shafts manual transmission

As mentioned above, the gear ratio is determined through the ratio of the number of gear teeth that are in interaction. For example: first gear = lower gear = highest gear ratio. All manual transmissions are divided into types according to the number of steps. There are four-, five- and six-speed manual transmissions. Nowadays, the most common “five-step” is a 5-speed gearbox, but a 4-speed one can be found very rarely.

In addition to the number of steps, manual transmissions are also divided into types according to the number of shafts. There are three-shaft and two-shaft boxes. Three-shaft gearboxes are equipped with rear-wheel drive vehicles (including heavy trucks), and two-shaft gearboxes are most often installed mainly on passenger cars with front-wheel drive.

Three-shaft gearbox device

The package of the three-shaft gearbox includes:

• drive shaft, also called primary and its gear;
• intermediate shaft with a block of gears;
• secondary shaft (driven), also with a gear block;
• the gearbox housing, called the crankcase;
• synchronizer clutches;
• direct gearshift.

In three-shaft gearboxes, as their name implies, three shafts work - the drive (primary), intermediate and driven (secondary). The drive shaft provides the transmission of torque to the intermediate shaft, with which it is connected using a gear. The intermediate shaft is also equipped with a gear block. The secondary (driven) shaft rotates independently of the primary, although it is located on the same axis with it and also has a block of its gears.

The body of the manual transmission is made of light metal. The entire gearbox mechanism is attached inside the case, and lubricant is poured there (most often, gear oil, although nigrol was used in old Soviet-style models).

The location of the shift lever can be different: sometimes the lever is located directly in the box, and sometimes it is mounted on the body. The mechanism responsible for remote gear shifting is colloquially called the "scene".

Two-shaft gearbox device

The package of a two-shaft gearbox includes:

• drive (primary) shaft, equipped with a block of gears;
• driven (secondary) shaft, also with a gear block;
• gear shift mechanism;
• main gear;
• synchronizer clutches;
• differential;
• gearbox housing.

So, this type of manual transmission has only two shafts. In general, the location and purpose of the parts of a two-shaft box is similar to a three-shaft one. The difference is only in the arrangement of the shafts (they stand in parallel) and in the principle of creating a transmission - if in a three-shaft it is created by two pairs of gears, then in a two-shaft one pair works. The two-shaft manual transmission does not have a direct transmission. Also, in two-shaft boxes, not one, but several driven shafts can be used at once.

For reverse gear in both two- and three-shaft boxes, an additional shaft and an intermediate gear are used. To keep the gear engaged (also for all types of gearboxes), clamps are used. To prevent two gears from being engaged at the same time, a blocking device is provided.

Synchronizers in gearboxes are used to silently engage the gear by equalizing the angular velocity of the gear and shaft. The standard package of the synchronizer includes two blocking rings, a coupling, crackers and wire rings. Using a synchronizer, you can alternately turn on the two gears of the secondary (driven) shaft.

The main breakdowns of the gearbox and their causes

1. Oil leakage. Most often it can be associated with damage to seals and seals. Also, the cause may be a loose fastening of the housing cover (crankcase). To get rid of leakage, it is necessary to change the seals and gaskets to new ones and / or tighten the covers.
2. The checkpoint is noisy. Most likely, the noise of the box is associated with a malfunction of the synchronizer. It can also be caused by worn gears, splines and/or bearings. In this case, wear parts should be identified and replaced.
3. The gearbox is hard to turn on. This may be due to a breakdown of some of the parts of the switching mechanism. Wear of gears and/or synchronizers is also possible. Check these parts and replace if necessary.
4. Transfers turn off by themselves. Most often this occurs due to a malfunction of the locking device, as well as severe wear of the synchronizers and / or gears. The method of troubleshooting is still the same - replacing the blocking device, gears, synchronizers - depending on which of them the breakdown is associated with.

In order for the checkpoint to serve you faithfully for a long time, treat it accordingly. The main advice when using the shift lever is to be literate in this process. Also, do not forget to change the oil in the crankcase from time to time. If you follow these simple points, the gearbox can last as long as the car itself, without reminding yourself of any malfunctions.

The main part of gearbox breakdowns is connected precisely with incorrect handling of the control lever. Do not pull the lever with quick and sharp movements - such tough operation may eventually lead to a major overhaul of the entire box, since the switching mechanism and synchronizers will fail very quickly (in fact, the same applies to shafts with gears).

Move the lever smoothly, take mini-pauses in the neutral position - then the synchronizers will work, which will protect the gear from breaking.

Do not forget to periodically check the oil level in the crankcase! Top it up if the need arises. Also, in due time, a complete oil change will be required - its terms are indicated in the operating instructions for the machine.

Video - The principle of operation of a manual transmission manual transmission

Conclusion!

And, of course - the classic, always relevant advice: listen to your car! A good driver always feels his iron friend and treats him with care. With this approach, you will not have to repair either the gearbox or other devices in your car.

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Today we will consider the device of a manual transmission, its positive and negative sides, as well as the most common malfunctions. Despite the very wide choice of cars equipped with automatic transmission, vehicles with manual transmission are still relevant. This is due to the fact that the reliability and resource reserve of mechanics is significantly higher than that of automatic analogues. In addition, cars with mechanics are much more frisky, and their control requires more activity from the driver when driving.

In the photo - the handle of the 7-speed gearbox

The transmission is designed to change the frequency of the torque transmitted from the internal combustion engine. In a manual unit, the driver himself decides which gear ratio should be included in a particular situation.

Modern passenger cars are usually equipped with five speed transmissions: four base and one overdrive. This is perhaps the best option for most drivers. These models include domestic and many imported vehicles, such as. However, there are models with a large number of steps. Manual transmissions with six or seven gears usually have five base stages and two or one overdrive.

Overdrive, or overdrive, has a gear ratio less than one. In other words, when overdrive is engaged, the driven shaft rotates faster than the drive shaft.

More expensive vehicles are equipped with six or seven speed manuals. For example, a gearbox or has six gear positions, and the latest generation Porsche 911 is equipped with a seven-speed manual.

It is worth noting that budget models, for example, Kia Rio or Hyundai Solaris 2016-2017, are already equipped with a 6-speed gearbox.

Advantages of a six-speed transmission

Naturally, a six or seven-speed gearbox compares favorably with five-speed units. First of all, it is worth noting that the switching process exhausts the internal combustion engine resource much less, since the transition from one speed mode to another is smoother. In addition, the fuel consumption of six-speed manual transmissions is somewhat lower, especially in the extra-urban driving cycle. Acceleration dynamics are much higher due to the fact that the gears are short.

In every modern car equipped with a six-speed manual, there is electronic equipment that notifies the driver of the need to shift. There is a similar thing in cars with a five-speed gearbox, but not always.

Manual transmission device

The transmission of a car is a multi-stage gearbox, the principle of operation of which is to alternately mesh individual gear pairs.

Clutch

The smoothness of switching from one gear to another in mechanics occurs due to the presence of a clutch assembly. It allows you to interrupt the connection of the transmission with the power unit for the time of switching. Its mechanism is an intermediate link between the car engine and gearbox. In addition to ensuring smooth shifting, the clutch assembly reduces vibrations transmitted from the internal combustion engine.

The clutch is divided according to the type of design and three types: friction, hydraulic, and electromagnetic.

The friction type is the most popular and can be single-disk, double-disk, multi-disk.

Today's vehicles are usually equipped with single disc models.

The principle of operation of the node is quite simple. The flywheel mounted on the crankshaft of the internal combustion engine acts as a drive disk. The driven disk is pressed against it with the help of a pressure plate, and pressing the clutch weakens this connection. The diaphragm spring provides optimal compression of the driven disc with the flywheel.

The pressure plate with the diaphragm is a one-piece design - the clutch basket. Baskets are both push and pull, but the first type is the most common.

With the help of splines, the driven disk is joined to the primary axis of the manual transmission. The smoothness of the transmission is due to the damper springs located on the disc hub. In addition, the slave is equipped with friction linings that are able to withstand high temperatures for a short time, when the clutch is engaged.

Gear shift

In each gearbox, shafts are located in parallel, on which gears are located. There are three-shaft and two-shaft transmissions. The shafts are called driving (primary), driven (secondary), also in the three-shaft type there is also an intermediate one.

Three-shaft type

The input shaft receives from the internal combustion engine, and from its axis, with the help of a rigid engagement with the drive shaft gear, the rotation is transmitted to the intermediate shaft. The secondary and primary axles are in the same plane and are joined together by a bearing. Due to this, their rotation occurs either completely independently or through an intermediate shaft. The gears on the secondary shaft do not have a rigid fixation, and are separated from each other by synchronizers that fit tightly on the shaft, but can walk along its axis with the help of splines. The end face of the synchronizer has gear rims that allow it to engage with similar rims on the gear wheel.

In the neutral position, the wheels rotate freely on the shaft, and the synchronizers are open. When the gear is engaged, the fork displaces the clutch and engages it with a certain gear.

From the secondary axis, the rotation goes to, or and in front-wheel drive cars. To enable reverse gear, an intermediate wheel is installed in the gearbox, which changes the rotation from the intermediate axle to the opposite.

Three-axle units are the most popular and are installed in almost every modern car.

Twin shaft type

The input shaft of a two-axle unit has many gears, not just one. Since there is no intermediate axle, its place is taken by the driven one with synchronizer couplings and gears installed on it. By and large, the difference lies in the presence of only one pair of engagements between the axles for each stage, and not two.

Switching is carried out in a similar way - a fork, controlled by a shift knob using a rod, shifts the clutch along the secondary shaft to the appropriate position.

The two-shaft type is characterized by high efficiency, but is limited in increasing the gear ratio, which is why this type of design is used extremely rarely. Due to the possibility of combining the gearbox, clutch assembly, and the internal combustion engine itself into a single unit, almost all small cars are equipped with this particular type of transmission. An example of the use of two-axle mechanics in a car with a front-mounted power unit can be considered the Citroen C3.

Important to remember!

Due to the fact that the intermediate gear that provides reverse rotation of the reverse output shaft does not have a synchronizer, the reverse gear should only be engaged after the vehicle has come to a complete stop. Otherwise, the gearbox will fail after such a switch.

Synchronizer clutch

Every modern transmission has synchronizer clutches. Their presence is important to simplify the switching mode. Without synchronizers, shifting would have to do a double clutch release in order to equalize the speed of the axles. On some types of special equipment, where gearboxes have a large number of steps, couplings are not used, since this is impossible.

On the inner circumference of the hub are splined grooves that allow the synchronizer to move along its own axis. When switching, the fork shifts the synchronizer along the splines until it mates with its pair at the end of a certain gear. When switching a stage, a significant force is applied to one of the blocking rings. Ultimately, the locking ring turns all the way.

In the photo - removing the synchronizer clutch

Further displacement of the synchronizer clutch without switching the stage is not possible. When the synchronizer engages with the gear ring, the elements are securely fixed.

Pros and cons of mechanics

The manual unit has both its advantages and disadvantages.

Pros:

Less costly transmission maintenance.

High efficiency.

Does not require separate cooling.

Cars with manual transmission are less voracious and have better dynamics.

The simplicity of the mechanics significantly increases the reliability of the unit.

Wider range of driving mode selection.

The vehicle is allowed to be towed.

Minuses:

Smooth starting and shifting require driving skills that only come with time.

A small resource of the clutch assembly.

During long trips, the driver of a vehicle with mechanics is much more tired than the driver of a car with automatic transmission.

The limited steps do not allow you to smoothly change the gear ratio.

Possible problems

Despite the simplicity of the design, the unit can break. If abnormal operation of the gearbox is detected, it is recommended to contact a car service as soon as possible. You can try to solve the problem yourself, but this will require both appropriate tools and certain skills.

The first thing worth stopping at is the occurrence of extraneous noise when the neutral gear is turned on. This can happen if the oil in the box has long exhausted its resource or it is not left at all. Usually, drivers change it extremely rarely, but if the transmission does not work correctly, the first thing you should pay attention to is the condition of the oil.

It can also leak due to the poor condition of the seals and gaskets. In this case, when changing the oil, other defective elements should also be changed. However, worn out bearings, gears, misalignment of the shaft axes can also be the cause of this problem. In this case, the box should be dismantled and completely sorted out, replacing worn-out structural elements.

There are situations when the driver has to make more effort to change gear than usual. This may be due to the failure of the switching mechanism itself or the incomplete disengagement of the clutch. However, damage to the stem lever may have caused the problem. To eliminate it, it is necessary to adjust the shifting or clutch mechanism, and it may also be necessary to replace damaged elements.

Some drivers have experienced transmission problems. This is often associated with wear of gears, forks, rods, bearings of the driven or intermediate shafts, as well as weakening their fixation. Since there can be quite a few reasons, in order to get rid of a manual transmission malfunction, it is necessary to completely sort out with the replacement of all defective structural elements.

Incompletely depressing the clutch pedal or driving the car with the clutch partially depressed is fraught with damage to the assembly parts. There is rapid wear of the clutch disc, and the petals of the diaphragm spring can simply break off. In addition, incomplete disengagement of the clutch when switching will soon necessarily lead to licking of the gears.

It is also worth mentioning that the strong vibration of the transmission when the internal combustion engine is running indicates that the docking of the two units is unreliable. Most likely, in this case, the weakening of the bolted connections is to blame; in this case, it will be enough to tighten them only more strongly. However, it is possible that the vibration is associated with the destruction of the supports, and then a very time-consuming repair will be required.

The occurrence of incorrect noise when shifting gears is most often associated with a clutch malfunction. The output shaft bearing may also be the culprit.

Careful use of any mechanism is a guarantee of its durability. The unpretentiousness of the mechanical unit attracts car owners. And yet, there are some recommendations regarding the use of manual transmission.

The first thing to remember is the importance of fully depressing the clutch pedal before changing gear. This is perhaps the most important moment in the use of mechanics. Also, the included gear must correspond to the driving mode. In addition, it is worth remembering that before switching to a lower gear, the speed must be reduced.

Despite the fact that, unlike the automatic machine, the mechanics can work without oil at all, this has a rather strong effect on its general condition. It is recommended to check the level and condition of the lubricant after passing 20,000 km. Despite the fact that most even experienced car owners never change the oil in mechanics at all, this is still completely wrong. It is advisable to change it at least after every 70,000 km of run.

The manual transmission is no longer the most common type of transmission used in cars today. However, it still remains quite in demand due to its reliability, simplicity of design and maintainability. The manual transmission gets its name from the "manual" (or mechanical) way of shifting gears. The transmission refers to stepped gearboxes in which the torque is changed by steps (gears). A manual transmission is considered the most reliable, but also the most difficult to manage, especially for a novice driver.

The principle of operation of a manual transmission

Manual Transmission

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

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

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

Types of manual gearboxes

According to the number of steps, a manual transmission is mainly divided into:

• 4-speed;
• 5-speed;
• 6-speed.

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

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

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

Manual transmission device

Manual transmission device

Structurally, a manual gearbox consists of the following elements:

• drive or input shaft;
• driven or output shaft;
• intermediate shaft (for 3-shaft manual transmission);
• gears of primary and secondary shafts;
• gear selection mechanism;
• synchronizer clutches (synchronizers);
• crankcase;
• main gear;
• differential.

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

Two-shaft gearbox: device and principle of operation

Scheme of a two-shaft manual transmission

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

The final drive gear is rigidly fixed to the driven shaft. Torque is transmitted from the secondary shaft to the wheels of the vehicle. The latter ensures the rotation of the wheels with different angular speeds.

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

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

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

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

Torque transmission schemes for each of the gears:

Three-shaft gearbox: device and principle of operation

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

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

Three-shaft manual transmission device

The intermediate shaft is parallel to the primary, all the gears on it are rigidly fixed.

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

Between the gears of the secondary shaft there are synchronizers, the work of which is to align the angular velocities of the gears of the secondary shaft with the angular velocity of the shaft itself due to friction forces.

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

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

It may also have a remote control. In this case, the remote switching mechanism is provided by a link or hinged cables.

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

A little about the manual transmission synchronizer

The synchronizer is used for shockless gear engagement due to the alignment of the angular velocities of the shaft and gear. Structurally, the synchronizer consists of a clutch, two locking rings, three crackers and two wire rings.

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

Advantages and disadvantages of manual transmission

For clarity, the positive and negative sides of a manual transmission are presented in the form of a comparative table.

Advantages	Flaws
The cost and weight of the box is lower compared to other types of gearboxes	Less driver comfort compared to other gearboxes
High acceleration dynamics, fuel economy and efficiency	Driver tiring shifting process
High reliability due to simple design	The need for periodic clutch replacement
Simple and inexpensive maintenance	Lower smoothness of the car in comparison with other types of gearboxes
Possibility of more efficient off-road driving
Ability to tow a car

Conclusion

Undoubtedly, the operation of a manual transmission is accompanied by many advantages. One economic side of using the box is worth it! And coupled with the reliability of the transmission and a more "driver's" driving experience, the manual transmission is an excellent solution for lovers of fast driving or off-road driving. If comfort is not paramount for you, then the choice in favor of manual transmission is obvious.