Where are the steps from the variator, what is the lifespan of these boxes and whether you need to change the oil? To these and other questions answered the expert “Behind the wheel”.Alexey Revin “driving”Expert
Truly a massive variable speed transmissions have become in the last decade. Therefore, even experienced drivers are not always well aware of what a CVT. And ignorance, as usual, generates a lot of misconceptions, misinterpretations and, as a result, bad advice.
Misconception 1. In the variator filled with oil for lifetime
In the same sentence contains two inaccuracies. First, the liquid is poured into the CVT should not be called butter. As well as in classical automatic gearbox uses ATF and CVT fluid is used with its own set of characteristics. Yes, the grease in this list is present, but it is not the main purpose of such liquid. For example, the working fluid to the variator pressure increases the friction coefficient in the contact area of a cone with a belt variator. Is conventional oil can do that? Of course not.
Classic slots are worn more non-metallic linings of the friction. And the CVT is a steel cones and a belt. Steel dust interferes with the operation of the valves, it can leave the system without fluid pressure, which is necessary for the operation of the entire automation box. Therefore, changing the fluid every 60 000 km are necessary. At the same time clean from debris trapping magnets and change the filter.
Misconception 2. The CVT includes a belt
In the majority of designs do you apply the strap drawn from a large number of steel plates held in by tape. But some manufacturers prefer to use chain. It looks almost the same as the timing chain of the engine. Only contacts with cones. Torque is transmitted to the ends of the rods connecting the plates. This variable is called a chain. Chain variators are used, for example, Subaru and Audi.
In zubrowska the applied CVT chain drive. Such a structure can withstand more torque than capable of convey belt.In zubrowska the applied CVT chain drive. Such a structure can withstand more torque than capable of convey belt.
Misconception 3. The CVT may not be the Converter. He’s the CVT!
On all cars with a CVT, which are sold in Russia, is also provided with a torque Converter. Always the first torque from the motor perceives it is the torque Converter on a classical machine. It slips when we are in traffic and the gear selector is in position D. the world has several models of variable-speed drives, where the torque Converter used a “wet” clutch. They had previously set on Japanese cars for the domestic market.
Misconception 4. If you go “on a cruise”, the CVT will operate with a constant gear ratio
This is incorrect. When driving on cruise control with a constant speed CVT even on a small lift will change the gear ratio, increasing the engine speed. Cruise control with hydromechanical automatic would add to the gas, i.e., opened throttle, and engine rpm in this case would remain unchanged.
Misconception 5. Cars with a CVT slow acceleration
The CVT delivers the fastest acceleration, which can give the engine. Only to obtain such a result we must not forget prozhat the gas pedal completely. In this mode (kick down) the engine quickly goes to the speed corresponding to maximum power, and further acceleration is due to the variable gear ratio in the CVT. This is the most efficient acceleration. Any other transmission paired with the same motor will be less efficient during acceleration.
Another thing is that the engine does howling almost on a single note. Monotonicity gives the impression too long acceleration, hence the confusion.
Misconception 6. With a CVT is not out of the mud or snow “vraskachku”
The CVT makes it relatively faster to switch from the drive range to the rear and back. And new models of CVTs, such as the Toyota RAV4, have a first mechanical transmission, which further facilitates the institutionalization, because switching back and forward occurs without the participation of the continuously variable transmission.
Misconception 7. Of the CVT there are no steps
Yes and no at the same time. This postulate is deny transmission including belt CVT, and two-stage reducer. Our motorists first saw it on the Nissan Juke, and now he got to Lada Vesta. It produces firm Jatco (Japan), index — JF015E. The point is that the CVT provides about half of the speed range for first gear, and then when you go to the second, again, implements a range. Thus, the transmission, in the classic sense, this CVT two. But most of these transmissions are trained to mimic a five or six-speed electronically. These programs are definitely not “real” and virtual.
On the latest tojtovska the variable-speed Direct Shift-CVT uses the first transmission gear engagement, and then connects the belt with the cones.On the latest tojtovska the variable-speed Direct Shift-CVT uses the first transmission gear engagement, and then connects the belt with the cones.
Misconception 8. The CVT is unreliable and not repairable
There is no more terrible and widespread myth of the variator. But in fact the years of operation and machines with large and very large runs proves otherwise. Most CVTs goes for 150 000 km or more. Problems arise or the lovers “to poggipolini”, or street racing. The CVT lives longer in the calm manner of driving, without extreme accelerations. And it is necessary to regularly change the fluid. Only under these conditions, the CVT can be put on a par with a hydromechanical machines in terms of reliability. Also don’t forget to monitor the cleanliness of the radiators, cooling the working fluid of the CVT. In the cold CVT, as the engine itself, it is desirable to warm up. In a place where touching the cones and the belt, the fluid starts to work properly only at temperatures close to working. When cold the liquid will be slippage, which will cause burrs on the surface of the cones and the belt.
Assume that the CVT started to submit first signs of wear. Came spurts at movement, the rattle at low speed, not very smooth acceleration, and the General behavior of the variator changed. If you start a repair early damage the main parts, then you can do a relatively inexpensive repair. Of course, the repair of the variator is not cheap, but usually turns out to meet the 50 000 — 70 000 rubles. This is the sum involves the replacement of the belt, grinding or replacement of the cones, replace the bearings and check valve of the pump. Simple hydromechanical machines are in most cases cheaper to repair.
And here’s the one real drawback
Actually, this is not a disadvantage — this is a normal limitation for a civil rather than a specially prepared racing cars.
If each traffic light to start “the last time”, and even when cold the CVT, then the friction belt members and the working surfaces of the cones encounter a bully. Resource unit enough twenty thousand kilometers or less. And no superticket not save you from this phenomenon. CVT is not for stritrejserzy feats, and for the most comfortable motion. Want to drive — there are special cars and, by the way, special tracks.
Probably in the near future the CVT will be installed for at least half of the produced cars. So treat it gently, change the working fluid, and then the CVT will last a long time.
- The whole truth about the (non)reliability of variators in this publication.