What is CVT box, and how does it differ from a traditional transmission? This question may interest both existing car owners with this type of torque transmission and future ones. This type of gearbox assumes no fixed gear ratios. This gives a smooth ride and also allows the engine to be used in optimal conditions. Another name for such a box is a variator. Next, we will consider the pros and cons of the CVT gearbox, the nuances of its use, as well as reviews of motorists who already own cars with a continuously variable transmission.
- The principle of the variator
- Advantages and disadvantages of cvt
- Possible problems in the operation of the variator box
- Cautions when using a CVT box
- Owner reviews
The abbreviation CVT (Continuously Variable Transmission – English) translates as “continuously variable transmission”. That is, its design implies the possibility smooth change the transmission ratio between the driving and driven pulleys. In fact, this means that the CVT box has a variety of gear ratios in a certain range (the limits of the ranges set the minimum and maximum diameters of the pulleys). Operation of a variator is in many ways similar to using an automatic transmission. You can read about their differences separately..
Today there are the following types of variators:
- disc ball;
The CVT box (variator) is used not only as a transmission for passenger cars, but also for other vehicles – for example, scooters, snowmobiles, ATVs and so on.
The most common type of CVT transmission is a friction V-belt variator. This is due to the relative simplicity and reliability of its design, as well as the convenience and possibility of using it in an automobile transmission. Today the overwhelming majority of automakers producing cars with a CVT gearbox use V-belt variators (with the exception of some Nissan models with a toroidal CVT gearbox). Next, consider the design and principle of operation of the V-belt variator.
CVT box operation
The V-belt variator consists of two main parts:
- Trapezoidal toothed belt. Some automakers use a metal chain or a metal plate belt instead..
- Two pulleys formed by cones, pointed towards each other.
As the coaxial cones are closer to each other, the diameter of the circle that the belt describes decreases or increases. The listed parts are CVT actuators. And electronics controls everything based on information from numerous sensors..
The principle of operation of the variator
Continuously variable CVT transmission device
So, if the diameter of the drive pulley is maximum (its cones will be located as close to each other as possible), and the driven pulley is minimum (its cones will diverge as much as possible), then this means that the “highest gear” is engaged (corresponding to the 4th or 5th transmission in a traditional transmission). Conversely, if the diameter of the driven pulley is minimal (its cones will disperse), and the driven pulley is maximal (its cones will close), then this corresponds to the “lowest gear” (the first in a traditional transmission).
For driving in reverse, additional solutions are used in the variator, usually a planetary gearbox, since the traditional approach cannot be used in this case.
Due to the design features of the design, the variator can be used only on relatively small machines (with engine power up to 220 hp). This is due to the high forces that the belt experiences during operation. The process of operating a car with a CVT transmission imposes some restrictions on the driver. So, you cannot start abruptly from a place, drive for a long time at maximum or minimum speed, tow a trailer, drive off-road.
Pros and cons of CVT boxes
Like any technical device, variators have their own advantages and disadvantages. But in fairness, it is necessary to take into account that at present, automakers are constantly improving this transmission, so over time the picture will certainly change, and the CVTs will have fewer drawbacks. However, today the CVT transmission has the following pros and cons:
|The variator ensures smooth acceleration without jerking, typical for manual transmission or automatic transmission.||The variator is now installed on cars with an engine power of up to 220 hp. This is due to the fact that very powerful motors exert excessive influence on the drive belt (chain) of the variator..|
|Higher efficiency. This saves fuel and transfers engine power faster to the actuators.||The variator is very sensitive to the quality of the gear oil. As a rule, it is necessary to buy only original quality oils, which are much more expensive than their budget counterparts. In addition, it is necessary to change the oil more often than in a traditional transmission (approximately every 30 thousand kilometers).|
|Significant fuel savings. It is the result of high efficiency and a smooth increase in engine speed and speed (in a traditional transmission, a significant overrun occurs during gear changes).||The complexity of the variator device (the presence of “smart” electronics and a large number of sensors) leads to the fact that at the slightest breakdown of one of the numerous nodes, the variator will be automatically transferred to emergency mode or disabled (forced or emergency).|
|High environmental friendliness resulting from lower fuel consumption. This means that machines equipped with a variator meet the modern high European requirements for environmental friendliness..||The complexity of the repair. Often, even minor problems with the operation or repair of the variator can lead to a situation where it is difficult to find a workshop and repair specialists for this unit (this is especially true for small towns and villages). And the cost of repairing a variator is much higher than a traditional manual transmission or automatic transmission.|
|The electronics that controls the variator always selects the optimum operating mode. That is, the transmission always works in the most gentle mode. Accordingly, this has a positive effect on the wear and life of the unit..||A trailer or other vehicle must not be towed on a machine with a variator.|
A trailer or other vehicle cannot be towed on a machine with a CVT. Also, you cannot tow the car itself if the engine is turned off. An exception is the case if you hang the drive axle on the tow truck.
Possible operational problems
In practice, owners of vehicles equipped with a CVT are faced with three main problems.
- Taper bearing wear. The reason for this phenomenon is trivial – contact with wear products (metal shavings) or debris on the working surfaces. A rumble that comes from the variator will tell the car owner about the problem. This can happen on different runs – from 40 to 150 thousand kilometers. According to statistics, this is a very bad thing for Nissan Qashqai. To avoid such a problem, it is necessary to regularly change the transmission oil (in accordance with the recommendations of most car manufacturers, this should be done every 30 … 50 thousand kilometers).
Reducing pump and valve
- Failure of the oil pump pressure relief valve. You will be informed of this by jerking and jerking of the car both during starting and braking, and during a calm, even ride. The cause of the breakdown, most likely, will lie in the same wear products. Due to their appearance, the valve is stuck in intermediate positions. Consequently, the pressure in the system begins to jump, the diameters of the drive and driven pulleys become out of sync, because of this, the belt begins to slip. During repairs, the oil and belt are usually changed, and the pulleys are ground. Prevention of malfunction is the same – change the transmission oil and filters on time, and also use high-quality oils. Remember that the CVT must be filled with gear oil of the CVT type (it provides the necessary viscosity and “stickiness”). Variable speed oil is characterized by ensuring stable operation of the “wet” clutch. In addition, it is more sticky, which provides the right grip between the pulleys and the drive belt..
- Operating temperature problems. The fact is that the variator is very sensitive to the operating temperature range, in particular to overheating. The temperature sensor is responsible for this, which, if the critical value is exceeded, switches the variator into emergency mode (sets the belt to the middle position on both pulleys). For forced cooling of the variator, an additional radiator is often used. In order not to overheat the variator, try do not drive at maximum or minimum speed for a long time. Also, do not forget to clean the variator cooling radiator (if your car has one).
Additional information about the variator
Many experts believe that the CVT (variator) transmission is the most advanced type of transmission today. Therefore, there are all the prerequisites for the fact that the variator will gradually replace the automatic transmission, as the latter confidently displaces the manual transmission over time. However, if you decide to buy a car equipped with a variator, then you need to remember the following important facts:
- the variator is not designed for aggressive driving style (sharp acceleration and deceleration);
- on a machine equipped with a variator, it is strictly not recommended to go for a long time at extremely low and extremely high speeds (this leads to significant wear of the unit);
- the variator belt is afraid of significant shock loads, therefore it is recommended to drive only on a flat surface, avoiding country roads and off-road;
- in the variator, it is imperative to change the transmission oil in a timely manner (and use only high-quality original oil).
Before buying a car with a CVT box, you need to be ready for its operating conditions. It will cost you more, but it is worth the pleasure and comfort that the variator provides. Thousands of motorists today use CVT transmissions, and their number is only growing..
CVT gearbox reviews
Finally, we have collected for you real reviews of the owners of motorists, whose cars are equipped with a variator. We present them to your attention so that you have the most clear picture of the advisability of choosing.
|Positive reviews||Negative reviews|
|You need to get used to the variator. I had the subjective impression that as soon as you release the gas, the car stops much faster than on the machine (most likely, the engine braking occurs). This was unusual for me, I like to go to the traffic light. And of the advantages – on the engine 1.5, the dynamics are freaky (not compared to the Supra, but compared to conventional cars with 1.5) and the fuel consumption is small.||All who praise the variator, no one can reasonably explain why it is better than modern, also smooth 6-7-step real hydromechanics, that is, the answer is simple, nothing, even worse (written above in the article). It’s just that these people bought a CVT not because it is better than an automatic machine, but because the car they decided to buy did not come with a real automatic.|
|The variator is more economical than an automatic machine (I compare it not with a Celica, but with any other car with a 1.3 engine||The variator is not encouraging. An interesting development, of course. But, given that the entire global auto industry is moving away from improving reliability in modern units, then nothing can be expected from variks (however, as well as from robots). Unless to switch to a consumer attitude towards cars: I bought it, drove for 2 years under warranty, leaked it, bought a new one. To which they lead us, in fact.|
|Pros – faster and more confident acceleration compared to automatic machines and mechanics (if mechanics are not a master of sports in auto racing). Efficiency. (Fit-5.5 L, Integra-7 L, both on the highway)||Why do you need a variator, when a “classic” automatic machine – smooth and super reliable – was invented long ago? Only one option suggests itself – in order to reduce the reliability and get enough on the sale of spare parts. And so the type, 100 thousand. the car has passed – everything, it’s time to go to the trash.|
|Last winter I went to a Civic with a variator, there were no problems on the ice. The variator is really more economical and dynamic than the machine. The main thing is that you get it in good condition. Well, a slightly more expensive service is a payment for driving pleasure.||In short, CVT = hemorrhoids, a marketing cartoon for disposable cars.|
|Seventh year on the CVT – excellent flight!||The old machine is as reliable as ak47, nafik these variki|
As you can see, most people who have tried to drive a variator at least once do not give up this pleasure if possible. However, only you can draw conclusions..
Although the variator is more complicated and expensive to maintain, it is still the best transmission for cars with an internal combustion engine. And over time, the price of cars equipped with it will only decrease, and the reliability of such a system will grow. Therefore, the described restrictions will be removed. But today, do not forget about them, and use the car in accordance with the manufacturer’s recommendations, and then the SVT box will serve for a long time as faithfully as the car itself.
Ask in the comments. We will answer necessarily!