Every driver, even those who just got behind the wheel, heard the acronym. P.C.But not everyone is concerned about the complexity of the processes behind these three letters. The gearbox is the only transmission unit that allows the internal combustion engine to operate in the optimal rev range at any speed of the car. Without this mechanism, a modern car would be either extremely slow or would have a monstrous fuel consumption and engine life of several thousand kilometers.
The principle of operation of this unit is based on a change in the gear ratio, which allows you to convert the torque coming from the engine into traction force on the wheels. When you move from a place, you need a huge force, but low speed, and when driving on the track – on the contrary, high speed with less effort. Exactly. transmission It takes on the task of balancing these parameters, ensuring comfort and economy.
In modern realities, the choice of the type of transmission becomes one of the key factors when buying a car. Understanding how your car works will not only help you avoid costly repairs, but also to operate the machinery properly in a variety of conditions. Let’s find out what types of nodes are, how they are arranged and why. mechanics It is still popular despite the dominance of automatic systems.
The main purpose and principle of transmission
The main function of any transmission is to change the magnitude and direction of torque transmitted from the engine to the driving wheels. The internal combustion engine is able to develop maximum power and torque only in a narrow range of turns of the crankshaft. If the torque was transmitted to the wheels directly, the car simply could not move from a place or accelerate to high speeds without overloading the power unit.
Inside the housing of the device are shafts and gears, which, entering into engagement with each other in different combinations, create different gear ratios. Transfer ratio This is the ratio of the number of teeth of the driven gear to the number of teeth of the leading gear. In the first gear, this number is maximum, which gives a huge effort on the wheels to move the heavy machine from a place, but the speed of rotation of the output shaft is minimal.
As the acceleration occurs, the driver or electronics switch gears to higher gears, where the gear ratio decreases. This allows you to increase the speed of movement while reducing traction, since the inertia of an already accelerated car helps to maintain movement. Also an important element is the possibility of reversing, which is realized by introducing an additional gear into the transmission chain, changing the direction of rotation of the output shaft.
⚠️ Attention: Never try to switch gears on a manual box without squeezing the clutch pedal to the end. This leads to rapid wear of synchronizers and the appearance of a characteristic crunch, which signals the destruction of the gear teeth.
In addition to changing speed and thrust, the box also allows you to disconnect the engine from the wheels while the engine continues to work. This is necessary to stop the car at a traffic light without jamming the engine. In automatic systems, this function is performed by a hydrotransformer or a friction packet, and in mechanical systems, dry or wet clutch.
Mechanical transmission: device and features
A mechanical transmission, often referred to as a “handle” or ICPP, is a classic and the most studied type of units. Its design is characterized by high reliability and repairability. The main elements here are the primary (leading) shaft, the secondary (sled) shaft and the intermediate shaft, on which gears of different sizes are located.
The key node that ensures smooth switching is synchronizers. These parts align the rotation speed of the gear and shaft before they are joined, preventing teeth from hitting. It is the presence of synchronizers that allows you to switch gears without double clutch, which was a mandatory procedure on older cars.
The steering process is controlled by the driver manually through a lever associated with the gear selection mechanism by cables or rods. This gives you complete control over the behavior of the car, which is especially appreciated in difficult road conditions or when driving sports. However, such a system requires the driver to have certain skills and constant attention.
Among the advantages of mechanics, one can distinguish high efficiency, since the loss of energy for friction is minimal, and the possibility of towing the car or starting the engine "from the pusher" without restrictions. In addition, the cost of maintenance and oil replacement in such units is usually lower than that of complex hydromechanical analogues.
Automatic transmissions: hydrotransformer and planetary series
A classic machine, or DISTRIBUTIONIt saves the driver from the need to constantly work with the lever and clutch pedals. The basis of this system is a hydrotransformer, which replaces dry clutch. It transfers torque from the engine to the box by flowing fluid (oil) from the pump wheel to the turbine wheel, ensuring smoothness and no hard connection at low revs.
The gearshift itself takes place inside a planetary series - a complex system of gears, satellites and drivers. Unlike mechanics, where the gears move physically, here they are in constant engagement. The transmission of torque to the desired planetark element is blocked or released by friction disk packets that are compressed by the oil pressure.
All this economy is managed by an electronic control unit (ECU), which reads data on the speed, position of the throttle and engine speeds. Modern machines can have from 6 to 10 stages, which allows you to keep the engine in the most economical mode of operation. However, this complexity makes the node sensitive to the quality of service.
| Type of PPC | Resource (km) | Oil-change interval | Cost of service |
|---|---|---|---|
| Mechanics (IPT) | 300 000+ | 60 000 - 90 000 | Low. |
| Classic automatic (ACT) | 200 000 - 300 000 | 40 000 - 60 000 | Tall. |
| Robot (RCPP/DSG) | 150 000 - 200 000 | 40 000 - 60 000 | Medium/High |
| CVT (CVT) | 150 000 - 250 000 | 30 000 - 50 000 | Medium |
It is important to understand that the classic machine does not like sharp starts from a place ("loon control") and prolonged slippage. The hydrotransformer in such modes strongly heats the oil, which can lead to loss of its properties and overheating of frictions. For winter operation, such boxes often require warming up before starting the movement.
Robotic boxes and preselectives
a robotic transmission, or RCMPThe mechanical part is a normal mechanics, but it is not controlled by the hands of the driver, but by electronic actuators (servo drives) or hydraulics. This solution was designed to combine the efficiency of mechanics with the comfort of the machine. Simple robots with a single clutch disc are often criticized for jerking and brooding when switching.
The revolution in this class was produced by preselective boxes, such as DSG from the VAG group or Powershift from Ford. Their design uses two shafts and two clutches: while the car is moving in the first gear, the second is already pre-on, but the clutch is open. The switching happens instantly by simply switching clutches, which takes a fraction of a second.
This design provides a high switching speed and excellent fuel efficiency. However, the complexity of the mechatronic unit (combined control and hydraulics unit) and the two-mass flywheels makes these units expensive to repair. The clutch resource in urban operation mode can be limited to 100-150 thousand kilometers.
Why do robots twitch in traffic?
The problem lies in the algorithms of the clutch. In the mode of constant touching and stopping frictions do not have time to fully close or open, being in the friction zone. Electronics try to compensate for this, but physical wear imposes its limitations, causing jerks.
Owners of such cars should be aware of the specifics of operation. In long traffic jams, it is recommended to transfer the box to neutral or use a special mode to not keep the clutch in a semi-squeezed state, which causes its overheating and accelerated wear.
CVT: No fixed transmissions
Variator, or CVT The continuously variable transmission (Continuously Variable Transmission) is fundamentally different from all previous types in that it does not have any fixed switching stages. Instead of gears, two sliding cones (shikva) and a belt or chain connecting them are used. By changing the diameter of the pulleys, the system smoothly changes the gear ratio.
This allows the engine to always run at the most efficient revs for the current load. When accelerating, you do not feel the tremors characteristic of gear shifting, and the engine speeds can monotonously hum at one level while the car is gaining speed. This ensures maximum smoothness and often better economy in the urban cycle.
However, the variators have their limitations. They don’t like high peak loads, so they’re rarely put on high-powered SUVs or sports cars (although technology is evolving). The chain or belt can stretch and the cones wear out, requiring timely oil and filter replacement.
⚠️ Attention: On the variator it is strictly forbidden to tow in snow or dirt. Attempting to “swing” the machine can lead to slipping of the belt and instant damage to the working surface of the cones, which will require expensive grinding or replacement of the unit.
Modern variators often simulate gear shifting software so that the driver feels the usual acceleration dynamics. This is done purely for comfort and has nothing to do with the actual mechanics of the process.
Typical malfunctions and extension of the PPC resource
Even the most reliable transmission is not eternal and requires proper handling. One of the main enemies of any unit is the late change of oil. In the process of work, metal shavings, wear products of frictions and moisture accumulate in the oil, which changes its properties and leads to bullying of surfaces.
A frequent problem of mechanical boxes is wear of the squeezable bearing and clutch basket, which manifests itself as noise when the pedal is squeezed or slipped. In machines and robots, speed sensors, solenoids or the mechatron itself often fail. Symptoms can be kicks when switching, going into emergency mode or the inability to turn on a certain gear.
To prolong the life of the transmission, you need to follow a few simple rules. First, always stop the car completely before switching between modes. D (drive) and R (reverse) Secondly, do not use neutral transmission at every short stop at traffic lights – this creates an extra load on the nodes. Third, let the box warm up in winter, smoothly starting the movement of the first couple of kilometers.
☑️ Checking the status of the PPC
Timely diagnosis can save from major repairs. If you notice a change in the behavior of the car, it is better to immediately contact the specialists. Ignoring minor problems, such as a slight hum or barely noticeable kicks, often leads to the fact that after a month you have to change the entire unit in the assembly.
When buying a used car, be sure to check the history of oil change at the checkpoint. If the seller claims that the oil is “forever” it is a worrying sign that the real life of any ATF liquid is limited.
FAQ: Frequently Asked Questions
How often should you change the oil in the gearbox?
For mechanics, the interval is usually 60-90 thousand km, but many experts recommend reducing it to 40-50 thousand in severe conditions. For automatic machines, robots and variators, the regulations are stricter - from 30 to 60 thousand km. The concept of “full life oil” is only applicable until the end of the warranty or the mileage of about 150 thousand. mile, after which the replacement is required.
Can I tow a car with an automatic transmission?
Towing a car with an automatic box is possible, but with serious restrictions. Usually this distance is not more than 30-50 km and speed is not higher than 40-50 km / h, since the pump supplying oil for lubrication and cooling does not work with the engine being silenced. It is best to use a tow truck.
Why is the box going into emergency mode?
Emergency mode (when the indicator lights up and the box is locked in one gear) is switched on by electronics when a critical error is detected. This can be low oil levels, sensor malfunction, overheating or problems with the electrical part. Operation in this mode is possible only for the journey to the service.
Which is better for the city: a robot or a variator?
For dense urban traffic, the variator is often more comfortable due to the lack of jerks. However, modern preselective robots (DSGs) also provide high comfort and accelerate faster. The choice depends on preferences: the CVT is smoothness, the robot is dynamics and clarity.
The main resource of any transmission is high-quality oil and timely updating. Don’t skimp on technical fluids, as transmission repairs are always more expensive than regular maintenance.