The CVT transmission uses a fluid-controlled tapered wheel to change the inner diameter, creating a compression force on the steel belt or chain and using friction to transmit power. It should be noted in particular that the CVT transmission transmits power through static friction, which means that no sliding friction is allowed between the spine wheel and the steel belt during the power transmission process because once sliding friction occurs, the frictional resistance will be greatly reduced.
In the process of relative sliding between the steel belt and the cone wheel, we can compare the relationship between the cone wheel and the steel belt to walking on ice. When the pressure between the sole and the ice is high enough to increase static friction, a person can walk on the ice. Once sliding friction occurs between the sole and the ice, slips and falls are inevitable. It is important to understand that the conical split disk of a CVT transmission is not smooth. Although it looks smooth with a polished surface, that is only what we see with our naked eye, or what we imagine; in fact, the conical split disks used in CVTs can be damaged even after mirror machining, which means that some wrinkles are added to the smooth conical surface at a later stage (similar to the wrinkles that are added to the honed surface on a cylinder liner)!
The purpose is to increase the friction of the tapered counterbalance, and secondly the corrugations act as an oil reservoir to prevent excessive wear of the CVT steel chain or belt with the counterbalance; in fact, many parts involving metal-to-metal contact are not absolutely smooth. This is common knowledge in the field of machining, and those who have done clamp work should understand this; secondly, oil does more than just lubricate, and in some specific scenarios the surface tension of the liquid is utilized to increase friction. This is the principle behind how CVTs have tons of hydraulic fluid but still inhibit slippage!
Conveyor Belt Edible Oil to Increase Friction
Folks who have been exposed to conveyor belts need to understand that applying a bit of grease to the machine prevents slippage between the conveyor belt and the rollers. Simply put, this is one example of using grease to reduce slippage; to take an even simpler example, a dry towel doesn't always stay on the incline. If a towel is wetted with water or motor oil, it can stay on a ramp with the same inclination. This is the principle of using the surface tension of a liquid to increase the friction of the contact surface. So don't be too narrow minded about oil and new conclusions will come out!
On an absolutely smooth surface, oil can form a film, thus blocking the direct contact between two surfaces, thus lubricating; whereas the surface of the cone splitter disk of the CVT has a textured surface, and the rough surface utilizes the tension of the oil to increase the friction. For example, the wet clutch of a wet powershift is soaked in the oil chamber as a whole, isn't it wet? But it's less likely to slip in practice, and instead utilizes the tension of the oil to transmit torque; so the oil inside the CVT increases friction instead!
The end face of the steel belt is in contact with the splitting disk
Because the Scheffler steel chain has a special anti-slip design, there's not much to talk about; as for the steel belt, it's actually in great contact with the conical splitting disk. The reason why many friends always think that this CVT drive slips is because they think the steel belt is flat (as shown in the picture above), and the contact area between the flat steel belt and the conical splitting disk is too small, so it will slip. I'm sure many of you think this; in fact, the steel belt is made up of a myriad of steel plates stacked on top of each other. The contact area between each steel plate and the conical disk is shown below (at the red arrow). The contact area is not small, and the steel plate inclination matches the cone-disk inclination exactly, making it very difficult to slip with enough pressure!
Pressure supplied by the pressure cylinder is precisely calculated
In fact, any CVT transmission undergoes rigorous testing before it is released to the market; the clamping force between the two conical splicing discs is precisely calculated. If the clamping force is too high, the life of the steel belt will be shortened, if the clamping force is too low, the belt will slip, so too much or too little clamping force. Then the problem is simple, as long as you find the right clamping force, it is well understood, right? Smooth again, under the action of absolute force will still be broken, so sticky slow oil steel ball will still be crushed by the hydraulic press, so as long as the clamping force is enough to prevent the slipping between the steel belt and the cone disk!
These are the reasons why CVT steel belts or chains are not prone to sliding friction. Let's just say that today's CVT transmission technology is much improved and there are many ways to inhibit slippage. So today's CVT transmissions are not prone to slipping, and their service life is greatly improved over the past. Improved; however, this is only relative. After all, a removed CVT can still see tapered folio discs with visible signs of wear after a long time, so there is no such thing as absolutely no wear, but there's no need to stress too much about it! Wear is everywhere, and today's CVTs aren't fragile; the conical disk surface isn't absolutely smooth, but the oil on the rough surface increases the friction (under enough pressure), so CVT slippage isn't common, because severe slippage would be the end of the line, so a functioning CVT doesn't have to worry about slippage!