What is more reliable – a CVT or an automatic? What is the difference? Advantages and disadvantages
Driving a car with a manual transmission requires attention, and a modern person is always in a hurry to get somewhere. An automatic transmission is much simpler in this regard. The electronics will think for the driver and perform all the necessary actions - you can not be distracted from the road.
But the design of automatic transmissions is much more complicated than manual transmissions. And the more complex the design, the lower its reliability. In the history of the automotive industry there are a lot of unsuccessful torque converter boxes; CVT systems have still been little studied.
Let's try to find out what is more reliable - a variator or an automatic transmission.
Automatic transmission: history
The first automatic transmission appeared in 1903, but it was used not in cars, but in the shipbuilding industry. The inventor of the design is the German professor Fettinger.
It was this man who first showed and proposed a hydrodynamic transmission that could decouple the propeller and power unit of ships.
This is how the hydraulic coupling was born, which is a very important component for any automatic transmission.
Later, already in 1940, Americans began to use the Hydromatic automatic transmission on Oldsmobile cars. It must be said that the design of the automatic transmission has remained virtually unchanged since that time. The automatic transmission consists of two main components.
This is a torque converter and gearbox. The first one performs the function of a clutch, and the purpose of its operation is smooth switching without jerking. The gearbox consists of pairs of gears in mesh.
This makes it possible to obtain a solid, fairly compact mechanism that has several stages at once.
Automatic transmission: technical part
Let's see how the automatic transmission works. This system has been worked out far and wide. Over the years, this design has been perfected. In general, the technical part is quite durable and reliable.
In torque converter boxes, the torque from the power unit is transmitted to the drive wheels through a “donut”.
It lacks rigid engagement. This system works thanks to oil that circulates under pressure. When there is no rigid engagement, then there is nothing special to break. But the design also includes shafts with planetary-type gears and friction discs. Clutch packs in automatic transmissions replace the clutch. When they are compressed or decompressed, the clutches corresponding to the specific gear are connected.
The automatic transmission has components such as a high-pressure pump and a valve body. This is the basis of any automatic transmission.
What usually breaks in an automatic transmission?
If you look at the statistics of automatic transmission breakdowns, you can see that most of them happen due to untimely maintenance. Not all owners change the operating oil even after long runs.
As a result, the valve body and automatic transmission radiator become clogged, and the filters become clogged. All this leads to the fact that the pump cannot create the required operating pressure. Because of this, the clutches spin and gears stop engaging.
Twitching and tremors appear.
Automatic transmission resource
It's hard to say which is more reliable - a CVT or an automatic transmission. At first glance it seems that it is a variator, since it has a slightly different device, without hydraulic equipment. But with high-quality and timely maintenance, the service life of a classic automatic transmission can be very long.
There have been cases when, if the oil is changed every 40 thousand kilometers, the box works for more than 400 thousand without breakdowns. Experts believe that the most reliable automatic transmissions are old Japanese four-speed gearboxes.
To increase the life of an automatic transmission, you must follow certain rules:
- It is required to change the oil according to regulations. If the manufacturer recommends changing the oil every 60 thousand, you should not ignore this period. This also applies to so-called maintenance-free “automatic machines”, where the liquid filled by the manufacturer is designed for the entire service life. This does not happen - the oil needs to be changed. The best option is a complete replacement with washing on a bench. This will ensure reliable and long-lasting operation of the transmission.
- Along with the ATP fluid, the oil filter is also changed. Its timely replacement can extend the life of the box by 20 percent.
- It is also necessary to periodically remove the radiator. It is purged and washed. Then they clean the bottom of the housing from debris - there may be chips, carbon deposits and much more.
By the way, the chips accumulate on special magnets. You can see what this phenomenon looks like in the photo below.
If you follow these rules, the service life of the automatic transmission will increase significantly. The box can go from 300 thousand or more. Because of this, many people choose this transmission.
Automatic transmission: advantages and disadvantages
Let's look at the main advantages of automatic transmission:
- The process of driving a car with an automatic transmission is greatly simplified - you no longer need to think about how to move the car, how slowly to release the clutch, what gear is best to engage. The computer will do everything itself.
- Automatic transmissions are also chosen for reliability. With proper care, automatic transmissions can travel more than 300,000 km. Another advantage is high maintainability. The design has been well studied, and a large number of specialists can repair automatic transmissions.
- Oil is also a plus for an automatic transmission. Automatic transmissions require a special fluid, but the requirements for it are much lower than for a CVT. And its price is less.
- Jerks and number of passes are also a plus. Today, multi-stage boxes are already found. There are even 12-speed models. They have a higher maximum speed threshold - the engine will not roar in fourth gear. Speeds are switched smoothly and unnoticed by the driver.
- Another significant advantage is the small amount of electronics. This relates to the question of what is more reliable – a CVT or an automatic transmission. Yes, the automatic transmission works together with the ECU, but the design contains no more than 30% electronics.
Now let's move on to the disadvantages:
- An automatic transmission cannot boast of such dynamics as a CVT or a manual transmission. The box also has lower efficiency. In an automatic transmission, the engine and transmission do not have a rigid clutch - everything is taken over by the torque converter. Therefore, part of the energy is spent on transmitting torque. When switching, there are noticeable shocks, which cannot be said about the variator. We'll look at the pros and cons below.
- Also, more oil must be poured into the automatic transmission - approximately 8-9 liters. At the same time, the variator requires no more than 6 liters. Another disadvantage is increased fuel consumption. On cars with a CVT variator it is the same as on a manual transmission.
To summarize, high reliability covers all the disadvantages of these units. With proper operation and regular fluid changes, the box can easily last more than 300 thousand km, which cannot be said about its opponent.
Many people believe that the CVT transmission was invented later than the automatic transmission. But that's not true. The operating principle was invented by Leonardo Da Vinci in 1490. But he could not introduce the unit, since there was no internal combustion engine at that time.
Then they forgot about the system and remembered only at the beginning of the 19th century on industrial machines. CVTs began to be used in cars in 1958, when Hubert van Doorn created the Variomatic.
It was then installed on DAF vehicles.
Device and principle of operation
This is one of the types of automatic transmission. CVT and automatic transmission - what's the difference? It consists in the absence of gears on the CVT transmission. The design consists of two pulleys on which the belt is tensioned (now, of course, it is metal).
The cones are not a solid structure, as before, but are made of sliding halves. If the drive pulley is not connected, the belt rotates along the small diameter of the cone.
When the pulley is moved, a low gear ratio is formed, which corresponds to the lower gears of the automatic transmission.
By moving the pulleys, you can very smoothly reduce gear ratios, that is, change gears (even though there are none). These numbers fully correspond to the stages in the automatic transmission. If you choose an automatic transmission or a CVT, the latter is more efficient. Here there is maximum efficiency, since torque transmission is rigid.
What breaks?
The design is very fond of quality service. The oil should be changed every 60-80 thousand km. Always change the fluid. If you don't replace it, problems will arise and restoring the box will be very expensive.
Problems include clogged hydraulic units and oil pumps. Because of this, the shafts cannot clamp or release the belt. As a result, it slips. This negatively affects its resource. The material wears out faster, and at one point the belt simply breaks.
And then literally everything inside will collapse. The working surfaces of the shafts also become lifted, which does not have the best effect on the condition of the belt.
CVT and automatic transmission - what's the difference? In a large, simply huge amount of electronics, which can make up up to 50% of the design.
CVT resource
Here, just like with an automatic transmission, it is necessary to change the oil strictly according to the regulations. If this is not done, the box will fail after 100 thousand. Also, every 120 thousand you need to change the belt. What is more reliable – a CVT or an automatic? It turns out that it’s “automatic”. You won't be able to drive 300 thousand with a CVT, even if you change the oil regularly.
Advantages and disadvantages
Here we are pleased with more dynamic acceleration and reduced fuel consumption. There are no jerks, efficiency is 10% higher than that of an automatic transmission. The car is easy to drive. But that's where all the advantages end.
We continue to consider the variator, the pros and cons of the design. Repairing such boxes is very difficult - the design is poorly understood, and there are still few specialists in this industry.
Periodic replacement of the belt is necessary. This is expensive, and not every service station undertakes such work. The design contains complex electronics. And finally, another significant disadvantage is oil.
It's expensive and hard to find.
What's better?
So, we looked at both transmissions. It's time to decide which gearbox is better - automatic or CVT. The CVT is better than the automatic transmission in terms of dynamics and consumption.
But in the event of a breakdown, repairs will be very expensive, and not everywhere this gearbox can be restored or at least serviced. The belt also requires regular replacement, and the structure itself requires high-quality oil.
The automatic transmission wins here more than completely.
Conclusion
We looked at the variator, its pros and cons. The verdict is this: if you are purchasing a new car that will have a warranty, then you can buy a CVT. If this is a car with a mileage of more than 100 thousand kilometers, then it is better to pay attention to the “automatic”.
Source: http://fb.ru/article/311017/chto-nadejnee—variator-ili-avtomat-v-chem-raznitsa-preimuschestva-i-nedostatki
Which is better: automatic or CVT? Let's figure it out together!
The good old manual transmission is gradually disappearing from the market. Modern car enthusiasts prefer comfort and a certain feeling of “freedom” behind the wheel, which became available to everyone with the advent of automatic transmissions.
But technological progress tirelessly rushes forward, bringing new automobile units to the market. We are talking about CVTs - a transmission that is the result of a symbiosis of mechanics and automatic transmission. Many modern car models are equipped with this type of box.
Like everything new, CVTs undergo experimental testing in practice, are refined, updated and improved.
So, until all automakers have equipped their cars with self-driving capabilities, drivers are faced with a dilemma: which gearbox to choose.
And the more cars are equipped with CVTs, the more questions arise: what is the operating principle of the CVT based on? Is this box secure? What is the difference between a CVT and an automatic if the car also has 2 pedals? Finally, which is better: automatic or CVT? These and some other questions will be answered in this article.
What is the difference between an automatic and a CVT?
Buying a car is an act that cannot be called spontaneous. One way or another, car enthusiasts prepare in advance for this event, find information about design features, power, operation, “sores,” etc.
If you miss this moment, you can quickly become disappointed in any car. To avoid negative emotions, you need to buy a car that meets your own requirements.
For example, it is worth clearly understanding what the fundamental difference is between an automatic transmission and a CVT, since some equate these units.
How does automatic transmission work?
The operation of the “automatic machine” is based on the principle of interaction between two main components: the torque converter and the gearbox. The torque converter builds up pressure, causing gears to shift smoothly and automatically. In fact, it was this unit that replaced the mechanical clutch.
The second automatic transmission unit - the gearbox - is responsible for the mechanical part of the transmission and consists of several stages, designated by pairs of gears that are in constant mesh.
How does a variator work?
The peculiarity of CVT gearboxes is continuously variable gear shifting. A pair of cone pulleys are responsible for a continuous increase in speed, one of which is driving, the second is driven. The pulleys interact with each other through a metal trapezoidal belt or chain.
What happens inside the variator during operation?
Cone-shaped pulleys are not monolithic parts. Each pulley is a series of sliding elements.
The lowest gear (initial or first) occurs at the moment when the drive pulley is in its maximum extended state and the chain runs along a small diameter.
Accordingly, when the drive pulley is extended to a minimum distance, the chain running diameter increases to a maximum, which is typical for fifth, sixth and higher gears.
This is the whole point of how a variator works: the movement of the pulleys changes the gear ratios, which leads to a decrease or increase in the speed of the car.
Automatic transmission VS CVT. Advantages and disadvantages
To put an end to the question “which is better: automatic or CVT?”, it is necessary to evaluate all the advantages and identify all the disadvantages of these types of transmission:
Advantages of automatic transmission
- An automatic transmission gives an undeniable feeling of comfort behind the wheel, especially when driving a car in city conditions, due to the absence of the need to constantly pull the gear shift lever. Owners of cars with an automatic transmission receive more confidence, ease of control and freedom behind the wheel. In addition, the car’s engine does not experience overload, and therefore is not subject to premature wear, due to the fact that gears are switched automatically and not forcefully.
Disadvantages of automatic transmission
- The automatic transmission has a relatively low efficiency due to the design features of the torque converter. As a result, cars with automatic transmission cannot be called economical in terms of fuel consumption.
- Weak acceleration dynamics, “dullness” and “dips” when accelerating are another significant drawback of the automatic transmission in comparison with the CVT.
Advantages of a CVT gearbox
- The CVT provides smoother acceleration and movement of the car.
- Low noise level of the box during acceleration.
- The throttle response and dynamics of the variator are much higher than automatic transmissions and manual transmissions, since no time is wasted on shifting gears.
- A car with a CVT will not stall at the wrong moment.
- The variator holds the car while stopping on an incline, preventing it from rolling down.
- The operation of the variator is controlled by a computer. The box is electronically adjusted to the operating mode of the internal combustion engine, the so-called “adaptation”, which allows you to operate the car in optimal mode, save fuel and avoid unnecessary loads leading to wear of the units.
Disadvantages of a CVT
- CVTs appeared relatively recently and are constantly being improved. Therefore, statistics on them have not yet been developed, and therefore, maintenance, and especially repair of these boxes, are very expensive procedures.
- CVT gearboxes require regular maintenance using specific oils, which differ fundamentally depending on the manufacturer and design features.
Conclusions. Which is better: automatic or CVT?
Having information about the features and operating principles of various types of transmissions, knowing their advantages and disadvantages, every car owner will find his own answer to the question “which is better: an automatic or a CVT?” When purchasing a car, car enthusiasts should rely on individual needs and inner driving instincts.
Perhaps for some, the proven reliability of an automatic transmission is a step higher than an innovative CVT. Someone, on the contrary, will choose advanced technologies, wanting to test their strength.
Everything in this world is improving, something new is always replacing the old.
In any case, the decision about which transmission – automatic or CVT – your next car will have is up to you!
Source: https://proautoprom.ru/chto-luchshe-avtomat-ili-variator/
CVT, robot or regular automatic – what to choose? – magazine Behind the Wheel
We recently expressed general thoughts about the pros and cons of the “handle” and the machine gun. However, they immediately promised to continue the topic: after all, automatic machines are not limited to hydromechanics alone. We understand robots, CVTs and other DSGs.
It is obvious that today there is nothing simpler, more reliable and cheaper than mechanics. Therefore, any step away from the usual “handle” will entail a certain set of problems - from technical to financial and even organizational: to take the same towing of a faulty car. As compensation for the absence of a third pedal, we get comfort and... But we’ll tell you about “and”.
Single clutch robot
Examples of use: Smart fortwo, Lada Vesta, Lada Xray.
Editorial Vesta with an auto-mechanical transmission (AMT).
Editorial Vesta with an auto-mechanical transmission (AMT).
The primitive “under-automatic” has supporters: many claim that driving with such a gearbox is convenient and comfortable. At the same time, the reliability of a simple unit is considered higher than that of hydromechanics and, even more so, a variator. Such a robot is based on conventional mechanics, but its clutch life is higher - according to factory data, by about 40 percent.
| The VAZ AMT is based on a conventional manual gearbox VAZ-2180 with a cable shift mechanism. The VAZ AMT is based on a conventional manual gearbox VAZ-2180 with a cable shift mechanism. | The AMT selector of the editorial Lada Vesta moves freely, regardless of whether the ignition is turned on and whether the brake pedal is pressed. You have to carefully monitor the display on the instrument panel. The AMT selector of the editorial Lada Vesta moves freely, regardless of whether the ignition is turned on and the brake pedal is pressed. You have to carefully monitor the display on the instrument panel. |
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I first encountered this type of gearbox when I rented a Fiat Grande Punto with a 90-horsepower turbodiesel and a single-disc robot in Italy in the mid-2000s.
On such a slope, the Fiatik gave me several gray hairs.
On such a slope, the Fiatik gave me several gray hairs.
Related materials
The car once treacherously rolled backwards so quickly that it almost damaged the wall of the castle that had stood there since the 14th century. Other memories include ugly acceleration, inappropriate behavior in traffic jams. Editorial Vesta and Xray with AMT also did not perform well when traveling around the city.
Jerky and unpleasant cars to drive. And the clutch life, according to a colleague who constantly drives Vesta, turned out to be very low.
In short, my opinion: a single-disc robot is a no-no.
It’s better to dance a jig on the pedals of a service Largus with a manual transmission in wild Moscow traffic jams, when it sometimes takes an hour to travel tens of kilometers, than such automatic machines.
Robot with two clutches
Examples of use: some models of Mercedes-Benz, BMW, Mini, Ford, most Volkswagen cars, including Audi, Skoda, Seat.
The essence of the idea is that separate input shafts and, accordingly, separate clutch discs are responsible for even and odd gears. If you are moving in first gear, then the second shaft is already rotating in second! Due to this, switching occurs very quickly - in milliseconds. Man is incapable of such agility.
At the same time, no jerks are felt during gear changes. Both “wet” clutch discs operating in oil are used - then this is a six-speed DSG 6 gearbox, and “dry” ones - a 7-speed DSG.
The service life of “dry” clutches is very limited and almost never reaches 100,000 km, and sometimes does not exceed 30,000 km during aggressive driving.
DSG gearbox with wet clutch for vehicles with transverse engine.
DSG gearbox with wet clutch for vehicles with transverse engine.
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Skoda with DSG robotic gearbox. A dream for the first 30–80 thousand kilometers.
Skoda with DSG robotic gearbox. A dream for the first 30–80 thousand kilometers.
Personal impressions are limited to trips in cars that Russian representative offices of various brands provide our publishing house for testing.
These machines are practically new, with low mileage, on which the characteristic problems of double-disc robots have not yet had time to manifest themselves. Everything looks great: fast, powerful, quiet - some advantages.
If you choose a car for personal use, and you have a lot of mileage to cover, then it is better to choose a traditional hydromechanical automatic or the good old mechanics as a gearbox.
CVTs
The cool thing about such a box is that there are no usual step-by-step switching here at all! Cone-shaped disks are attached to the input and output shafts, which together form a kind of pulley with a variable diameter.
The shafts are connected by a transmission - V-belt, chain, etc. By shifting the cones relative to each other, you can smoothly change the gear ratio. The toy is not cheap.
Operation requires a special transmission fluid, the level of which must be carefully monitored.
There are quite a few types of CVTs - the main ones are listed below.
V-belt variator
Examples of use: Nissan Qashqai, Nissan X-Trail, Renault Kaptur, Mitsubishi Outlander, etc.
Continuously variable transmissions are often installed on popular crossovers. The logic is simple: a box that is more comfortable to operate has not yet been invented for a family car.
Continuously variable transmissions are often installed on popular crossovers. The logic is simple: a box that is more comfortable to operate has not yet been invented for a family car.
The V-belt variator is by far the most common type of continuously variable transmission. The torque is transmitted by a metal push belt. The ends of the trapezoidal elements placed on the tape, in contact with the cones, cause them to rotate.
At the same time, a conventional torque converter with locking is used, as on hydromechanical automatic machines. When starting off, the torque converter increases engine torque by up to four times greater.
The use of this unit ensures a smooth start to movement when moving in city traffic jams.
A CVT can be even more compact than a manual transmission.
A CVT can be even more compact than a manual transmission.
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V-chain variator
Examples of use: Audi A6, Subaru Forester.
The device is similar to a V-belt variator, but instead of a belt, a metal chain consisting of plates connected by wedge-shaped axles is used as transmission. It is the ends of these axles that transmit torque. Another difference is that Audi gearboxes use a clutch pack and a dual-mass flywheel instead of a torque converter.
The CVT installed on Audi is designed for a longitudinal engine arrangement.
The CVT installed on Audi is designed for a longitudinal engine arrangement.
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Both types of continuously variable transmissions have recently been made with virtual steps. Supposedly, drivers like this better because the engine doesn't howl at the same note.
Typically, the variator quickly overheats when driving on serious off-road conditions. It's enough to skid a little. But there are also exceptions. For example, the Subaru Forester, equipped with a CVT, is capable of much beyond the asphalt.
Typically, the variator quickly overheats when driving on serious off-road conditions. It's enough to skid a little. But there are also exceptions. For example, the Subaru Forester, equipped with a CVT, is capable of much beyond the asphalt.
In terms of consumer properties, a variator is the best type of gearbox. It provides fast acceleration, and as for the monotonous sound... I remember Hottabych removed the sound of the engines of a flying plane, but what did that lead to? Participants in the events barely escaped...
On a flat highway, at a car speed of just over a hundred, the engine speed does not reach 2000. There is engine braking. Personally, I’m afraid about the service life of the belt and in winter it’s not even the engine that warms up, but the variator.
And so - the perfect gearbox (ugh, not gears)!
And, yes, I forgot: CVTs do not roll back on a slope!
Good old hydromechanical gearbox
Examples of use: almost the entire range of Korean and American brands, as well as relatively powerful cars from other manufacturers.
It is a stepped planetary gearbox connected to the engine through a torque converter. The selection and switching of planetary gears used to be carried out hydromechanically, but now ubiquitous electronics, together with the engine management system, determines which gear the power unit should operate in at the moment.
The number of stages is constantly increasing, reaching nine on the most expensive cars.
One of the most advanced hydromechanical transmissions is the Daimler 9G-TRONIC automatic transmission, which is used on models with a longitudinally mounted power unit.
One of the most advanced hydromechanical transmissions is the Daimler 9G-TRONIC automatic transmission, which is used on models with a longitudinally mounted power unit.
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Related materials
Four-speed hydromechanical gearboxes satisfy modern requirements less and less. During acceleration and when operating in the city, the shifts are felt quite noticeably. At highway speeds, fuel consumption is high due to the inability to provide optimal engine speed.
Even a slight increase in fuel supply leads to a transition to third gear, and the engine revs up even more.
What stands out here is the all-French four-speed DP0 gearbox. This box and its numerous reincarnations are still installed on a huge number of relatively low-power Peugeot, Citroen and Renault cars.
Most often in our country, owners of such cars as Peugeot 307, Citroen C4, Renault Logan (with the whole family) and Megane encountered this box. The nature of the box is quite obstinate; there are some glitches with switching. Reliability is also not outstanding: a rare gearbox of this type survives up to 80 thousand km without repair.
Moreover, sometimes it is possible to get by by replacing the valves, and sometimes you have to change half of the “filling”.
But the “all-Japanese” manufacturer of automatic machines Jatco managed to make a relatively problem-free “four-stage”. One of the versions is even installed on the sedan and hatchback, produced in our country under the Japanese brand Datsun.
And yet, for a modern car with a hydromechanical automatic transmission, the number of stages should be at least six. The extremely popular Rio and Solaris in the latest generation fully confirm this.
Multi-speed automatic transmissions are much more economical, especially when driving on the highway. On powerful business sedans, heavy crossovers and SUVs, there is no alternative to hydromechanical transmissions and is not yet in sight.
Most likely, they will become hybrid, and then the entire transmission will be configured completely differently. But that is another story.
conclusions
For severe operating conditions, for powerful engines, or in a situation where the car you like is not available with another type of automatic transmission, you can take a hydromechanical gearbox . But with the number of steps not less than six.
The CVT is good in small and medium-sized cars (no larger than a mid-size crossover).
a car with a robotic gearbox and two clutches only if you are going to drive it no longer than the warranty period.
Further, all the benefits will be offset by expensive repairs.
Cars with a single-disc robot , in my opinion, have not achieved perfection in the field of ease of traction control and are not highly reliable in difficult conditions.
In conclusion, as always, I look forward to your comments. What type of gearbox do you like, drive, and dream about?
Source: https://www.zr.ru/content/articles/907460-peresazhivaemsya-s-mekhaniki-na-a/
CVT or automatic, which is better to choose? What is the difference and what are the advantages of transmissions
Which is better - a CVT or an automatic ? This question is often asked by people planning to buy a new car with one transmission or another. There is a huge amount of conflicting information on the Internet, in which it is very easy to get confused.
We offer you comparative characteristics, advantages and disadvantages in design and maintenance, information about which is collected from reviews of real owners of cars with these two transmissions, as well as information on the design and operation of both the CVT and automatic transmission.
https://www.youtube.com/watch?v=vGEkhIGTPKw
We'll consider:
CVT design and operation
Before we move on to the comparative characteristics of the variator and automatic transmission, it will be useful for you to know the structure and operating principle of the first and second units. This information will help you draw the right conclusions at the end of the story. So, let's start with the variator.
Belt variator
The main difference between a variator (Continuosly Variable Transmission, CVT) and any gearbox (both automatic and manual) is the absence of fixed gears .
Each such unit has a certain range in which the transmission force (number) is located under certain conditions at a specific point in time.
This becomes possible due to the fact that the operation of the variator is based on a different operating principle than that of the gearbox.
How does a variator work? Its principle of operation is to use a belt drive (most often in modern cars a metal belt or chain is used), which transmits forces between the drive shaft (from the engine) and the driven shaft (which goes further to the wheels).
In this case, the gear ratio changes smoothly due to the smooth change in the diameter of both the drive and driven shafts. For this, special techniques are used. Each modern automaker has its own developments in this area.
However, all variators can be divided into two main types:
CVT operation
The basis of the V-belt drive is a trapezoidal toothed belt (some automakers use a chain or belt made of metal plates). The second component is two pulleys, which are formed by conical disks. They can change their diameter, making it possible to change the speed and value of the transmitted torque.
The work occurs according to the following algorithm. When the driver presses the accelerator pedal, the drive pulley transmits rotation from the engine to the driven shaft.
However, its design is created in such a way that under the action of centrifugal forces, due to an increase in revolutions, the cheeks of the disks are compressed and push the drive belt from the center of the pulley to its edge. And on the driven shaft the reverse process occurs.
That is, his cheeks unclench and the belt moves to the center of the pulley. This is how the gear ratio and effort change smoothly. When the accelerator pedal is released the reverse process occurs.
Scheme of operation of a toroidal variator
The toroidal variator has a different operating principle. Instead of shafts, it has two wheels with a spherical surface. The rollers are sandwiched between. One of the wheels is driving, the second is driven.
A change in the value of the transmitted torque and gear ratio occurs due to a change in the friction force between the wheels and rollers. Changing the position of the rollers in the transverse plane allows you to change the gear ratio.
When the roller is horizontal, the drive and driven wheels rotate at the same angular speed. When the rollers change their position, the gear ratio also changes.
However, due to the complexity of design solutions and manufacturing technologies for individual parts, toroidal variators are rarely used. Therefore, in the future we will talk about V-belt devices , as the most popular in the automotive industry.
CVT oils are different from other transmission fluids. They have the corresponding designation - CVT. The fact is that these oils not only lubricate, but also prevent slippage .
It is thanks to this property that it becomes possible to use the belt to transmit torque between shafts. In this regard, “oil starvation” should not be allowed.
Otherwise, the belt or chain will begin to slip along the working surfaces of the shafts, thereby significantly wearing them out.
Automatic transmission operation
Automatic transmission torque converter
The main elements of an automatic transmission are a torque converter and a mechanical gearbox. In this case, the torque converter acts as an automatic clutch, and the gearbox transmits mechanical force between the gears.
Torque from the engine shaft is transmitted through a torque converter, which operates based on the available oil pressure. The automatic transmission design also includes steel discs with friction clutches, as well as clutches.
They perform the mechanical function of the clutch, that is, when they are compressed and decompressed, the necessary couplings are engaged, which in this case act as gears in the box.
Automatic transmission has its advantages and disadvantages, which we will discuss later. They will allow us to see how a CVT differs from an automatic and what is better in certain conditions.
CVT operation
Automatic transmission operation
Advantages and disadvantages of a variator
For clarity, we present the pros and cons of the variator in the form of a table.
| Advantages | Flaws |
| Smooth movement. The car accelerates without jerking, which is typical for a gearbox. The movement is reminiscent of riding an electric car (such as a Tesla) or an electric lift. | The CVT cannot be installed on cars with powerful engines (from 220 hp and above). This is due to the fact that powerful engines exert significant force on the drive belt or variator pulley. |
| High efficiency. Thanks to it, the time required to transfer useful power from the engine to the transmission is significantly reduced. Because of this, the car becomes more dynamic when accelerating. This is especially felt at speeds of 50-60 km/h and above. | High cost of gear oil. In addition, the variator is very demanding on its quality. Therefore, as a rule, it is necessary to buy only original oil, which costs much more than budget analogues. |
| Significant fuel savings. It becomes possible thanks to smooth acceleration and braking and higher efficiency than that of an automatic transmission. | The presence of a large number of electronics and sensors increases the likelihood of failure of the electronic variator control system. As a result, as a result of even a minor electronic failure, the variator can be switched to emergency mode or simply turned off. |
| A car with a CVT is more environmentally friendly due to lower fuel consumption (less CO2 emissions). | Difficulty of repair. Often, when malfunctions occur, the problem arises of finding car services that repair CVTs (this is especially true for small towns). In addition, the cost of repairs will be higher than for an automatic transmission. |
| Gentle operating mode. The choice of operating conditions is largely carried out by electronics, which selects optimal operating modes in order to reduce wear of parts and extend their service life. | A car with a CVT cannot tow a trailer or other vehicles, or tow the car itself with the engine turned off. |
Remember that a car with a CVT cannot tow a trailer or other vehicles. Also, you cannot tow the car itself with the engine turned off. The exception is when the drive axle is suspended.
Now, to complete the picture, let's move on to describing the advantages and disadvantages of an automatic transmission. This will give us the opportunity to decide which is better - an automatic transmission or a CVT.
Advantages and disadvantages of automatic transmission
We will also provide information about them in the form of a table.
| Advantages | Flaws |
| High reliability of the unit. Modern automatic transmissions are designed for operation with a mileage of several hundred thousand kilometers (more than 300 thousand kilometers are guaranteed, usually more with proper care). In this case, any operating conditions are possible. The same applies to the automatic clutch, whose functions are performed by the automatic transmission. | Low efficiency caused by significant losses in the torque converter. Therefore, not all the useful engine power is used, |
| Relatively easy to repair. Unlike a CVT, repairing an automatic transmission does not present any particular problems. Most service stations do this. In addition, the cost of automatic transmission repair is much lower. | High fuel consumption. This is a consequence of the previous point. Cars with automatic transmission consume more fuel than cars with a CVT. |
| Automatic transmissions are not so demanding on the quality of gear oil. It is not necessary (although it is advisable) to use the original oil; you can get by with a cheaper analogue. | Worst dynamic characteristics. In particular, the acceleration of a car with an automatic transmission is slower than that of an analogue with a CVT or manual transmission. |
| Gentle treatment of the engine. Gear shifting occurs without the need to set high engine speeds. | The car jerks when automatically changing gears (although modern multi-speed gearboxes are less susceptible to this drawback, since they have a larger number of gears). |
| Larger amount of transmission oil used (8-10 liters versus 5-8 for a CVT and 2-3 for a manual transmission). |
In a word, automatic transmission today is a more reliable system, especially with a mileage of over 100 thousand kilometers. The only condition, as with any automobile unit, is timely and sufficient care.
Here are a few more interesting facts that will certainly help the future car owner, and he will be able to decide which gearbox is better - an automatic or a CVT.
Acceleration schedule for a car with a CVT and automatic transmission
- The volume of transmission oil in an automatic transmission is larger (albeit slightly, it depends on the specific model). But this often does not affect the cost, since the price of the original CVT fluid is usually higher.
- The oil and filters on the variator must be changed more often . And during operation, make sure that it does not turn black and lose its characteristics, since its quality is critically important for the unit.
- Typically, automakers recommend changing the oil in the variator every 60 thousand kilometers. However, according to reviews from many car owners of cars with a CVT, it is better to do this earlier, at approximately 50 thousand . Moreover, it is necessary to replace not only the oil itself, but also the filters, since they are inexpensive.
- With a CVT you cannot start abruptly from a standstill . The whole essence of its work comes down to optimizing speed and torque so that the mechanism works in a gentle mode. Therefore, if you like to “drive”, then this transmission option is clearly not suitable for you. Also, the CVT cannot be used to slip or pull trailers or other vehicles .
- Long driving at both the highest and lowest speeds is equally harmful for the variator . The fact is that under these two conditions the belt experiences significant mechanical stress, which causes it to wear out. In addition, the oil temperature increases. Additional cooling should be considered. Therefore, if you often stand or move slowly in city traffic jams, then think again about the advisability of buying a car with a CVT transmission.
- When operating a car with a CVT in severe frost, be sure to warm up the engine in order to reduce the viscosity of transmission and other oils. Otherwise, the variator belt will slip, further wearing out its surface and the surfaces of the pulleys.
- It is not advisable to buy a car with a CVT on the secondary market . There is a high probability that problems will arise primarily with this node. Checking the condition of the belt is quite simple. To do this, you need to drive a car on a flat road at low speed for a distance of about 1 kilometer. If you feel jerks while driving, you will definitely have to refuse to buy such a car.
- Monitor the status of the speed sensor . If it fails, the electronics switches the variator to emergency mode. If this happens while driving, then “engine braking” is performed, which can be harmful for the car.
- Timely change of oil for the variator is extremely important . The fact is that if the oil loses its performance properties, the variator valve body will gradually become clogged, and accordingly, the oil pump will not be able to pump up normal operating pressure. As a result, the shafts will not be able to compress and decompress the belt, it will begin to slip on them and wear out greatly. In the worst case, it will rupture and “tear” all the insides of the variator.
- The variator belt must be replaced every 120...150 thousand kilometers, regardless of its condition.
Let's summarize..
Despite all the existing shortcomings, today CVTs are the most advanced type of transmission . Their benefits have been appreciated by tens of thousands of drivers around the world.
As for the disadvantages mentioned, automakers are constantly working to improve the design of CVTs, so we can say with confidence that they will gradually push automatic and manual transmissions out of the market.
Finally, we will provide information in order to give a better understanding of who is most suitable for buying a car with a CVT transmission:
- the CVT does not like aggressive driving style;
- It is not recommended to drive with a CVT transmission for a long time at extremely low or high speeds;
- when operating the variator at very high or low temperatures, it is necessary to create special conditions;
- a car with a CVT cannot be towed with the engine turned off (it can be towed with the drive axle hanging out ), and also it cannot be used to tow other vehicles or trailers;
- It is advisable to drive only on smooth roads, since the variator drive belt is afraid of significant shock loads;
- Change the oil and drive belt in a timely manner.
Thus, before buying a car with a CVT, you need to prepare yourself for the conditions of its future operation. Especially if you have previously used exclusively a manual transmission. However, over time you will get used to it and will probably be satisfied with the choice. Just don’t forget to maintain the CVT transmission on time and follow the vehicle operating rules described above.
Conclusion
Taking into account all the information given above, we can say that there is no clear answer to the question of which is better - a CVT or an automatic transmission. After all, these two units are very different from each other, and each has its own characteristics.
Therefore, the choice must be made based on the operating conditions of the machine . In addition, remember that currently on the domestic car market there are CVTs that are far from perfect (“raw”).
Automakers are constantly working on their development, and there are all prerequisites that in the future they will take their place in the market.
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Source: https://etlib.ru/blog/555-variator-ili-avtomat-chto-luchshe
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