Many may be interested in the question of what is a checkpoint? So, speaking in dry language, the gearbox is designed to change the torque that is transmitted to the drive wheels from the crankshaft. And if you look from the point of view of a beginner to the question of what a gearbox is, and why shift gears, then there are a lot of difficulties. Gear shifting is a necessity arising from the fact that the engine torque is not uniform. You can compare the engine with an electric motor.
The main difference between them from the point of view of interest to us is the traction characteristics, that is, how the torque changes depending on the number of revolutions of power. The electric motor has significant torque at low speeds. The indicator drops as it unwinds. This characteristic is most favorable for the car during start from a place and subsequent acceleration, when it is necessary to overcome a large inertia force, it is at this time that it is best to have as much torque as possible. Even movement requires much less torque to maintain it. At any speed, the power of the electric motor can remain almost maximum, and it can be used almost completely in all modes, that is, it is perfectly adapted to road conditions.
If we talk about an internal combustion engine, then everything is completely different, at reduced speeds its power is significantly reduced, and the moment value does not change much in the range of operating numbers. The traction characteristics of such an engine can hardly be called satisfactory. However, for other indicators, a power plant with a similar motor is noticeably superior to an electric motor. Since the designers were forced to put up with such shortcomings, the car was equipped with a gearbox to overcome them. So what is PPC? It is intended to change the gear ratio between the engine and the main wheels.
Understanding the question “PPC - what is this?” It is worth saying that a different torque can be obtained through the use of gears of different sizes. If you put the intermediate gear between the driven and the leading, you get a change in the direction of rotation of the driven, which gives us a reverse gear. It turns out that any gearbox: automatic, robot, CVT or mechanical serves to ensure the most optimal mode of engine operation in various conditions by changing the same gear ratio.
Any gearbox has lower and higher stages. When starting from a place, acceleration, subsequent movement at an insignificant speed or off-road, you need the highest torque achievable at medium-high speeds, however, there is no need to develop high speed. The movement in this mode is provided by the lower steps in the gearbox, which have a small gear ratio, which means that even at high engine speeds the car will move slowly.
Uniform movement at high speed can be achieved only in the case of a high frequency of rotation of the wheels, as well as while maintaining the engine speed at the optimum range. This is possible thanks to higher gears, which have lower gear ratios. The car will travel much faster with similar engine speeds until it reaches maximum speed. However, at the highest gear, the car cannot move at low speed, and also does not budge, since the necessary torque is not developed, and the car itself stalls. So, you should understand what a checkpoint is and why it is needed in a car.