The scheme of the manual transmission. The principle of operation of a manual transmission

The gearbox, or in other words the transmission, transfers 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 the torque in full or in part.

A vehicle going uphill should be in a lower gear than a vehicle traveling on a level highway. In a lower gear, more torque is transmitted to the wheels. And this is required when the car is moving slowly, because it is hard for it. More high gears suitable for faster vehicle movement.

There are gearboxes with manual control, but there are also automatic ones. To change gear in a manual transmission, the driver first depresses the clutch pedal (picture on the left). This disconnects the engine from the gearbox. The driver then shifts the control lever to another gear and releases the clutch pedal. The engine is reconnected to the gearbox and can transfer its energy back to the wheels. AT automatic box gears, the position of the gas pedal (accelerator) is related to the speed of the vehicle, and the gear is automatically changed if necessary.

Manual transmission control

The diagrams alongside show how the control 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) are applied to the wheels. Engine power is not transferred to the wheels.

Neutral transmission. Engine power is not transferred to the wheels.

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

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

Third gear. The third pair of gears works together with a clutch mechanism. The vehicle speed is even higher and the torque on the wheels is less.

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

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

Accelerator operation

Engine RPM depends on how much fuel is pumped from the carburetor to the cylinders. Fuel movement is controlled by the carburetor throttle valve, and 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 his foot, throttle opens and more fuel flows into the engine. If the driver releases the accelerator pedal, the flap is closed and the amount of fuel supplied is reduced. At the same time, both the engine speed and the vehicle speed decrease.

Automatic transmission

When applied automatic transmission, the driver does not have a clutch pedal under his foot. Instead, a torque converter paired with planetary gear (picture on the right and below) automatically disconnect the engine from the drive shaft when, according to driving conditions, it is necessary to change gear.

And after the gear has changed, the drive shaft is reconnected. Should the driver put the control lever in working position, and the automatic transmission mechanism itself will choose the right gear in accordance with the current driving conditions.

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

mechanical;

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

Mechanism

Before starting to study the device of a manual transmission (manual transmission) and the principles of its operation, you should describe in detail this mechanism. Mechanical box gears are an integral part of any vehicle equipped with an engine internal combustion... Its mandatory presence is due to the specifics of the operation of modern motors, which have a fairly small speed range, within which the maximum values \u200b\u200bof power and torque are achieved. In addition, any engine has a critical speed value, exceeding which invariably leads to premature wear of the unit, up to and including its failure. Before the transmission of torque to the secondary shaft and to the wheel drive of the vehicle, the manual transmission changes the direction of this vector physical quantity and transforms it. The transition to each new stage in the manual transmission is carried out by mechanically moving the lever to one position or another.

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

Components of the manual transmission:

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

Operating principle

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

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

Locking mechanisms prevent the possibility of spontaneous disengagement of gears, while locks prevent the simultaneous engagement of several gears.

Number of steps and shafts

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

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

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

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

The location of the shafts. In a two-shaft gearbox, the shafts are parallel to each other;
The transfer process. In a gearbox with three shafts, the transmission is created due to the work of one pair of gears, in a three-shaft gearbox - due to the interaction of two pairs;
Direct transmission. The two-shaft gearbox has no direct transmission.

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

Video

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

What car unit comes to mind right after the engine? What inspires horror and awe to the students of driving schools, but causes a satisfied smile on the faces of experienced drivers? What mechanism do many of us work with for several hours a day, sometimes without even knowing about the principle of its internal structure? Yes, the answer lies on the surface: it's a manual transmission. Having told about the main problems that arise with, having dealt with the myths and rumors about, we decided: it is enough to undeservedly deprive the attention of the most important, simple and, in spite of everything, popular variation of the mechanism that turns the engine from a boiler for burning fuel into the heart of the car.

Visual material

Especially for this material, the company"PacPac" provided us with a FischerTechnik kit that schematically shows the principle of operation of a manual transmission, and we were even able to assemble it. Let us pay special attention to the fact that it conveys only the most basic properties, completely disregarding a number of phenomena occurring in a real automobile gearbox: it has neither clutches, nor forks, nor synchronizers, and the choice of gear is realized by moving the input shaft itself. If it were a real metal "mechanics", it would not live long, scattering after several dozen switchings. Nevertheless, looking at this fearless little "gearbox", dashingly poking them into a fixed output shaft without synchronization, one can see and understand the main purpose of the unit: to make it possible to change the gear ratio using gears of different sizes. And this is already something.

FischerTehnik constructor demonstrating the principle of manual transmission

Inventing the bicycle

Starting the story about the gearbox, it is worthwhile to briefly understand - why is it needed at all? After all, everyone knows that the main thing in a car is the engine, so is it really impossible to directly transfer the work it does to the wheels without inventing complicated schemes with a bunch of gears, a third pedal in the cabin and a lever that must be constantly turned over? Unfortunately not.

The best way to answer this obvious question is to look at the bicycle, or rather, its evolution. The simplest version is two sprockets connected by a chain drive. Rotating one - leading - sprocket with the help of pedals, the rider sets in motion the second - driven, connected directly to the wheel, thus rotating it. The bike is moving forward, everyone is happy and satisfied. At least, they were up to a certain point - as long as the bicycle was used to move on relatively flat and horizontal surfaces. Suddenly finding out that sometimes there are upsides, loose soils and other inconveniences on the way, people started thinking about improving the design. The result is what can be called the prototype of a manual transmission - sets of sprockets at the front and rear, allowing you to change the gear ratio.

The gear ratio is a quotient, obtained by dividing the speed of the driving star by the speed of the driven one, that is, the number of their revolutions. It is inverse to the gear ratio, which is calculated as the ratio of the number of teeth on the driven sprocket to their number on the driving sprocket. Simply put, the smaller the leading star and the larger the driven, the easier it will be to rotate and the slower it will move. Thinking back to old bicycles: in the front, the pedals had to rotate a large sprocket, while the sprocket on the rear hub was small. As a result, trying to get under way in some "Ural" in childhood, I had to put all my weight on the pedals in order to crank rear wheel... Well, now stores abound with a scattering of two-wheelers, even the most budgetary of which have several stars in the back and front. This makes it possible, for example, to change the set: the driving sprocket will be small and the driven sprocket large. Then the pedals will rotate very easily, but you won't be able to accelerate too much. But it will be possible to go up the hill, not drag.

From bike to car

What did all this detailed cycling information refer to? This is exactly why a gearbox is needed at all: after all, the characteristics of the energy source, be it a cyclist or an internal combustion engine, are constant. The first develops a certain muscle strength, limited by physical capabilities, and for the second, opportunities are expressed by the number of revolutions developed. The fact is that in their operating range it is simply impossible to pick up such a gear ratio that will allow you to confidently get under way and accelerate to 150 or more kilometers per hour. The situation is aggravated by the fact that if the cyclist has the maximum available practically idle speed”, Then the situation with the internal combustion engine is different: to achieve it, the revolutions must be quite high. Yes and maximum power, also important for movement, appears in their upper range.

What is the conclusion from this? You will have to resort to the same technique as on a bicycle: change the gear ratio. Between what and what? Let's figure it out now.

And now - to the gearbox itself

Basically from a bicycle drivetrain car box gear differs in the type of drive: if the first uses a chain, then the second is based on a gear mechanism. In general, they have the same essence: both there and there the gears (stars) have different sizes, providing a different gear ratio. By the way, initially, in the early gearboxes, they were simple spur-toothed, and later became helical, since in this case their quieter operation is ensured.

In general, a manual transmission is a set of parallel shafts on which gears are "strung". Their task is to transfer torque from the engine flywheel to the wheels. In the classic case, either two or three shafts are used for this. Consider a three-shaft option, from which it will be easier to switch to a two-shaft one.

So, in the three-shaft version, the gearbox has a primary, secondary and intermediate shafts. At the same time, the first two are located on the same axis, as if being a continuation of each other, but independent and rotating separately, and the third is physically located under them. The input shaft is short: at one end it is connected through a clutch to the engine flywheel, that is, it receives torque from it, and at the other end there is a single gear that transfers this moment further to the intermediate shaft. It, as we remember, is below the leading one and is already a long rod with gears on it. Their number coincides with the number of transmissions, plus one for connection with primary shaft.

The gears are rigidly fixed to the intermediate shaft, often they are turned from a single metal workpiece. They can be called leading (although they are driven through the input shaft). Constantly rotating, they transmit torque to the driven gears of the secondary shaft (by the way, there are exactly the same number of gears here, by the way). This third shaft is similar to the intermediate shaft, but the main difference is that the gears on it are a moving element: they are not rigidly connected to the shaft, but threaded onto it and rotate on bearings. In this case, their longitudinal movement is excluded, they are located strictly opposite the gears of the intermediate shaft and rotate with them (although there is another option when the gears can move along the shaft). One end of the secondary shaft, as we remember, is facing the primary, and the second serves directly to transmit torque to the wheels - for example, through the cardan and the rear axle gearbox.

So, we got a design where the primary shaft, when the clutch is closed, rotates the intermediate shaft, and that one simultaneously rotates all the gears on the secondary shaft. However, the output shaft itself is still stationary. What should be done? Switch on transmission.

We turn on the transfer

Engaging a gear means connecting one of the gears of the output shaft to itself so that they begin to rotate together. This is done as follows: between the gears there are special couplings that can move along the shaft, but rotate with it. They play the role of "locks", with the help of toothed rims at their contacting ends, rigidly connecting the shaft to the gear, to which the coupling is adjacent. It is set in motion by a fork - a kind of "slingshot", which, in turn, is connected to the gearshift lever - the same one that is wielded by the driver. The gearbox drive can be different: lever (using a metal shaft), cable and even hydraulic (this is used on trucks).

Video: FischerTechnik gearbox - First gear

Now the picture is more or less formed: by moving the clutch to one of the gears of the secondary shaft and closing them, we achieve rotation of the shaft and, accordingly, the transmission of torque to the wheels. But there are a few more "chips" that need to be mentioned.

Synchronizers

First, let's imagine a gear change while the car is moving. The clutch, moving away from the gear, unlocks it and goes to the neighboring one (or another clutch will come into play, between the other gears). It would seem that there are no problems here ... However, everything is not so smooth: after all, the clutch (and, accordingly, the output shaft) now has one rotation speed set by the previous driven gear, and the gear of the next gear — another. If you just sharply combine them, a blow will occur, which, although it will instantly equalize the speeds, will not bring anything good: firstly, the gears and their teeth can be corny damaged, and secondly, changing gears in this way is generally not the best idea. How to be? The answer is simple: before engaging the transmission, the speed of the gear and the clutch must be synchronized.

For these purposes, parts are used, called - suddenly - synchronizers. The principle of their operation is as simple as their name. The simplest solution is used to synchronize the speeds of two rotating units: friction force. Before engaging the gear, the clutch comes close to it. The contact part of the gear has a conical shape, and a counter cone is located on the coupling, on which a bronze ring is installed (or several rings, since these parts, as you can understand, are subject to the main wear). Pressing against the gear wheel through this "spacer", the clutch accelerates or decelerates it to its own speed. Then everything goes like clockwork: since now the two parts are stationary relative to each other, the clutch easily, smoothly, without jerks and jerks, engages with the gears by means of gear rims located in the mating zone, and they continue to move together.

Direct and overdrive

Let's move on to the next point. Let's imagine that, gradually accelerating, we have reached such a speed of movement of the car, at which the engine is able to provide what we talked about at the very beginning - the direct rotation of the wheels without the help of additional gears. What is the easiest solution to this problem? Remembering that the primary and secondary shafts in a three-shaft gearbox are located on the same axis, we come to a simple conclusion: you need to connect them directly. Thus, we achieve the desired result: the rotation speed of the engine flywheel coincides with the rotation speed of the secondary shaft, which directly transmits torque to the wheels. Ideally! In this case, the gear ratio is obviously 1: 1, so this is called direct.

Video: FischerTechnik gearbox - Second gear

Direct transmission is very convenient and profitable: firstly, energy losses due to rotation of intermediate gear wheels, and secondly, the wheels themselves wear out much less, since no effort is transferred to them. However, we remember that the gears of the intermediate and secondary shafts are always in mesh, and it does not disappear anywhere, so they continue to rotate, but already "idle", not transmitting torque.

But what if we go even further and make the gear ratio less than one? No problem: this has been practiced for a long time. In fact, this means that the driven gear will be smaller than the driving gear, and, therefore, the engine at the same speed as in direct gear will operate at lower revs. Benefits? Reduced fuel consumption, noise and engine wear. However, the torque in such conditions will be far from the highest, and for movement you need to maintain great speed... An overdrive gear (also called overdrive) is mainly used to maintain this speed in constant motion, and when overtaking you will most likely have to downshift.

Twin shaft gearboxes

As we promised, we will move from a three-shaft gearbox to a two-shaft one. In fact, the differences in their structure and operation are minimal. The main thing is that there is no intermediate shaft, and its role in in full takes over the primary. There are stationary gears on it, and it also directly transmits torque to the output shaft.

Also, from the misalignment of the secondary shaft relative to the primary, the second difference of the two-shaft gearbox follows: the absence of a direct transmission due to the banal physical impossibility of rigidly connecting these two shafts directly. This, of course, does not interfere with choosing the gear ratio of overdrive gears so that it tends to a value of 1: 1, but the drive in any case will be carried out through the gears with all the attendant losses.

Of the obvious advantages of a two-shaft box, one can note its compactness compared to a three-shaft one, but due to the absence of an intermediate row of gears, the variability in the selection of gear ratios is reduced. Thus, it can be used where lighter weight and dimensions are more important than high torque and a wide gear ratio.

Instead of a conclusion

Of course, in this article, we left out some technical subtleties and nuances. The exact design of synchronizers with breadcrumbs, springs, balls and retaining rings, the features of operation of unsynchronized gearboxes, the differences and advantages of existing types of drive clutches for gear shifting - all this was deliberately left aside in order not to overload detailed information those who are just trying to understand the principles of "mechanics". Just for such an audience, this text was written - hardly a person familiar with internal device gearbox, learn something new from it. But for beginners who want to find out what is there, at the other end of the manual transmission salon lever, the article may be useful. After all, knowledge gives not only theoretical knowledge - now it will become clear to many how to properly operate your car: why it is not worth turning on gears that are not intended for driving at the selected speed, why you should not rush to switch or portray with a "sequencer" when operating a civilian car in ordinary urban conditions, why do you still need to change the oil not only in the engine, but also in the gearbox. And if someone thinks or makes new conclusions for themselves, it means that all this was not written in vain. And this, as you know, is the most important thing.

Well, is it now clear how the manual transmission works?

To begin with, the need to "dock" a car engine and gearbox usually arises after power unit filmed for. It is also quite often necessary to remove the box itself, since this unit in some cases requires a bulkhead or replacement (especially in the case of automatic transmission or manual transmission, better known as "automatic" and a robot box).

As a rule, after the repair of units, certain difficulties may arise at the stage reassembly, namely when trying to connect the engine to the box. In this article we will talk about how to attach a manual or automatic transmission to a car engine.

Read in this article

Connecting a gearbox to a motor: features and nuances

Immediately, we note that the connection of a manual transmission, as well as a robotic transmission, is somewhat different from a similar operation with another type of transmission, that is, an automatic torque converter automatic transmission. Otherwise, the usual mechanics and the "robot" (especially the one-disk one) are very similar in their structure.

So, let's start with the manual transmission using the example of the popular hyundai models Getz. Join given type boxes can be in any garage, even without inspection pit... It is important to take into account that a certain free space under the car is still necessary.

To solve the problem, it is necessary to raise the front axle of the car, substituting wooden blocks, etc. It is also advisable to invite an assistant before starting work, but in extreme cases you can do it yourself.

After raising the car, you must first remove the intermediate steering rod, since the element will complicate the process of connecting the engine and the gearbox, taking into account the installation at an angle relative to the body.

It is also necessary to remove the gear lever from the checkpoint, and the hole after removal should be closed with a rag, masking tape, etc. Please note that after installing the box, the specified lever will be mounted from the passenger compartment, so you should figure it out in advance on the removed transmission with how this element is installed back into the box.

Even before removing the lever, you need to engage the fourth gear. We add that in the case when the clutch unit was also removed from the motor, it is imperative to center the driven disc in relation to support bearing... This is done using a special mandrel or by removing the input shaft from the box.

If this is not done, the input shaft during installation will not enter the specified place, that is, it will not be possible to install the gearbox. Next, loosen the bolts on the engine mountings by loosening the nuts that secure the upper metal brackets. This is necessary in order for the engine to be able to stand at a certain angle, and without the risk of damaging the pillows themselves.

The front of the engine is then lifted slightly just before installing the box. As a result, the rear part (clutch installation area) is slightly lowered, and the gearbox is able to enter the tunnel when installed from below and connect with.

It is important to prepare everything in advance. necessary tools, fasteners, etc., and spread them out so that you get free access. We are talking about the head, spanners, bolts for fastening the box to the engine and other elements.
Now you can proceed to the installation phase. If you have not previously practiced this operation and do not know how to connect the engine to the box, carefully study the following recommendations:

You need to be prepared for the fact that you will have to lie on your back and hold the checkpoint, lifting the unit with your hands. The task comes down to getting the input shaft into the clutch disc.
Further, the gearbox housing will need to be "scrolled" a little so that, together with the output flange (or a rubber coupling), it is possible to realize the alignment of the splines on the input shaft with the splines of the driven disk.
After the splines are aligned, the box will move with relative ease towards the engine with little effort. The only caveat is that certain difficulties may arise with the guide bushings.
After installation, you need to tighten one or a couple of bolts so that the box does not detach. Next, tighten all the remaining fasteners with the required force and in the required order (information can be found in the manual).

Connecting the automatic transmission to the engine

Taking into account that the automatic transmission does not have a classic clutch and differs in its design from the manual transmission and manual transmission, the automatic transmission connection has its own characteristics.

First of all, a torque converter must be connected to the motor (they will perform the function of a clutch), and this detail should definitely stand on its own seat... To check this, after installation, it is necessary to separately measure the distance from the rear end of the cylinder block to the plane of the drive plate. It is with this plate that the torque converter is docked. (a)

It is also necessary to measure the reciprocal size along the gearbox to the plane of the torque converter (b). The specified plane connects to the drive plate. Calculations can be carried out using the formula, where dimension b is equal to dimension a + 2 + 4 mm.

Please note that the specified clearance is leveled after the torque converter is fully pulled to the drive plate, however, this clearance must be present during installation. If there is no clearance, then there is a risk of damage to the drive plate, as well as damage to the oil pump. The parts are expensive, so extra care must be taken.

Let's go further. At that moment, when the box is raised for installation, you need to pay attention to the fact that the torque converter does not fall out. Lift the box at an angle to prevent it from falling. Then the mounting holes on the torque converter (GT) are aligned with the counter holes that are made on the drive plate itself.

Further assembly is carried out by tightening all bolts with the required torque, which enter the centering sleeves. Then the drives, hoses, etc. are connected. At the end, you should check that the GT does not experience any difficulties during rotation (the part scrolls freely).

Also, in the process of installing manual transmission and automatic transmission on a car, you should adhere to some recommendations. In all cases, be sure to check the crankshaft rear oil seal for possible leaks. If problems are found, the oil seal must be changed immediately, since otherwise further leakage will require the gearbox to be removed again.

As for the automatic transmission, this unit usually has a separate cooling radiator. It is necessary to make sure that such a radiator is not dirty, all pipes must be free to blow through. The automatic transmission radiator itself is washed by supplying gasoline or a similar cleaner under pressure through a tube, allowing you to remove chips, deposits and other debris.

You also need to pay attention to the fact that there are two special guide bushings between the engine and the box. If there are fewer bushings or they are absent, then sooner or later the bushing oil pump the "automatic" box will turn, oil from the box will begin to flow at the junction of the gearbox and engine.

As a result, the box will need to be removed; there is also a high probability of the need to replace the oil pump. It is also recommended to always blow and clean all contacts and electrical connectors that were previously disconnected when the transmission was removed.

The box body should easily attach to the engine. In the case of automatic transmissions, this is especially important. Also, only after making sure that the connection is normal, you can tighten the parts with bolts. For example, if the automatic gearbox rests against the drive plate with the torque converter, and on the mechanical gearbox in, while the gearbox does not dock with the internal combustion engine, the bolts cannot be tightened. Otherwise, you can damage the oil pump on the automatic transmission, as well as other elements on different types transmissions.

Finally, we note that after installing the box, connecting and configuring, it is also necessary to separately check the oil level. With the "robot" and "mechanics" in this regard, it is a little easier, since it is enough to put the car on a flat area and unscrew the control plug. If oil leaks out, the level is normal. Some other cars with these types of gearboxes have a separate oil dipstick boxes.

As for the automatic transmission, the oil level should be checked only after the engine is warmed up to operating temperatures, and it is also important that the gearbox itself also warms up. As for checking the oil level in an automatic transmission, this is done only with the engine running.

Principle of operation and device

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

Clutch

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

The clutch unit is necessary, since a significant torque passes through the manual transmission.

Gears and shafts

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

In three-shaft there are three shafts:

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

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

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

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

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

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

For a two-shaft box, a drive shaft connection with a clutch block is also provided. In contrast to the three-axle design, a block of gears is located on the drive axle, and not one. Intermediate shaft no, but the driven shaft runs parallel to the drive shaft. The gears on both axles rotate freely and are always engaged.

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

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

Synchronizers

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

Synchronizer manual transmission

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

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

The synchronizer works this way. When the driver engages the gear, the clutch moves towards the desired gear. During movement, the force is transferred to one of the clutch lock rings. Due to the different speeds between the gear and the clutch, the tapered tooth surfaces interact with frictional force. She turns the locking ring onto the stop.

Synchronizers operation

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

Gear shift process

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

a simple structural solution;
ensuring the clarity of switching;
more durable design for operation.

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

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

floor between the driver's and front passenger seats;
on the steering column;
in the area of \u200b\u200bthe instrument panel.

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

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

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

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

Gearshift mechanism Lada Granta

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

Advantages and Disadvantages of Manual Transmissions

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

Advantages:

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

disadvantages:

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

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