The gearbox is one of the three major parts of the automobile, and it is the most important part in the automobile transmission system. Its function is to distribute the power output by the engine, generate different transmission ratios between the engine and the wheels by shifting gears, amplify or reduce the torque output by the engine, and make the engine always work in the best torque range and give full play to the best performance of the engine. It is a high-tech assembly component, and its precision even exceeds that of the engine. So now there are many manufacturers that can produce engines in the world, but only a handful can produce automatic gearboxes.
Gearboxes in automobiles can be roughly divided into two categories: manual gearboxes and automatic gearboxes. Automatic gearbox can be subdivided into hydro-mechanical automatic gearbox (AT), continuously variable gearbox (CVT), double clutch gearbox (DCT) and automatic clutch gearbox (AMT). Let’s analyze the advantages and disadvantages of these gearboxes in detail to see which one is more suitable for use in mountainous areas.
1. Manual gearbox (MT)
As the name implies, a manual transmission is a transmission that can only change the gear engagement and transmission ratio inside the transmission by pulling the transmission lever by hand. Its advantages are simple structure, low manufacturing cost and maintenance cost, high reliability, fuel saving and high transmission efficiency; The disadvantage is that the operation is more complicated, requiring higher driving skills and greater labor intensity.
2. Hydromechanical Automatic Transmission (AT)
Hydromechanical automatic gearbox is what we often call AT gearbox, which is a traditional automatic gearbox. Its advantages are simple operation, automatic speed change and torque change according to road conditions, effective avoidance of engine overspeed and overload work, high reliability and mature technology; Disadvantages are complex structure, high precision, troublesome maintenance, relatively low transmission efficiency, relatively high fuel consumption, and relatively high price of models equipped with AT gearbox.
3. Continuously variable transmission (CVT)
CVT in English is mainly composed of torque converter, driving cone, driven cone, pressure steel belt and gear. The pressing mechanism of driving and driven cone exerts pressing force on the pressure steel belt to change the rotating radius of the pressure steel belt on the driving and driven cone, thus realizing the change of transmission ratio, so its speed ratio change is continuous. Its main advantages are good driving comfort, enabling the engine to always work in the most economical speed range, good fuel economy and relatively simple structure; The disadvantage is that the transmission steel belt of CVT can bear limited torque, so it is not suitable for intense driving and extreme off-road, and the maintenance is difficult and the cost is high.
4. Dual clutch gearbox (DCT)
Dual-clutch gearbox is equivalent to two manual gearboxes connected in parallel and controlled by two clutches. When the gearbox works, one set of gears is engaged, and the gears of the next set of gears are preselected. When shifting gears, only the clutches are separated and combined. Its main advantages are ultra-fast shifting speed, high bearing capacity, high transmission efficiency and good economic fuel consumption; The disadvantages are precise structure, complex manufacturing process, poor reliability, serious setback at low speed and very bad driving experience.
5. Automatic clutch gearbox (AMT)
Automatic clutch gearbox is abbreviated as AMT in English, which is based on the traditional manual gearbox and is equipped with a set of system for automatically controlling clutch and shifting mechanism. Its advantages are high transmission efficiency, compact structure, low cost, easy manufacture, reliable work and convenient operation. Disadvantages are strong frustration caused by gear change, poor shift comfort, and power interruption during shift, which makes the acceleration performance during shift poor.
There is also a kind of manual-automatic gearbox that people often say. Strictly speaking, it can’t be regarded as a type of gearbox. It just adds a manual mode to the automatic transmission, and the driver can choose the gear independently according to the engine speed and speed, which can not only increase some driving pleasure, but also increase the power when driving on a slope and accelerating overtaking, so as to make the car more maneuverable.
Now let’s take a look at which gearbox is suitable for use in mountainous areas. Mountain roads are characterized by many steep slopes, and the road conditions change greatly. Gearboxes need to change gears frequently to meet the power demand of automobiles. So which of these gearboxes can adapt to this road condition?
The first thing to be excluded is the CVT gearbox. This kind of gearbox bears limited torque, which is easy to overload on large slopes, and has cold protection and thermal protection, so it is easy to break down on mountain roads. Secondly, the automatic clutch gearbox is excluded. This gearbox has a serious shift and a long shift time, so it is easy to miss the best shift opportunity. In case the gearbox power output is interrupted due to the failure to shift in time, it is very dangerous on the complicated and changeable mountain roads. There is also a manual transmission model, which requires high driving skills, and requires the driver to switch to the appropriate gear at any time according to the speed and road conditions. In addition, it is often necessary to start on a hill road, which requires very high driving skills, so try not to choose a manual transmission model.
The rest are hydro-mechanical automatic transmission (AT) and dual clutch transmission (DCT). How should they choose? One of the biggest disadvantages of the dual-clutch gearbox is that it is seriously frustrated when driving at low speed, and frequent gear changes make the dual-clutch easy to overheat, which is often encountered when driving in mountainous areas, so the dual-clutch gearbox is not the best choice; Finally, only the Hydro-mechanical Automatic Transmission (AT) is left, which bears a large torque and can be overloaded for a short time. Even if it changes gears frequently, it will not overheat, which is very reliable in technology. In addition, it has a crawling mode and can travel at a very low speed, which is very practical in extreme road conditions in mountainous areas. Therefore, it is the best choice to drive hydro-mechanical automatic transmission (AT) on mountain roads frequently.
Finally, talk about the skills of driving on mountain roads. On mountain roads, it is best to put the gear lever in manual mode, and the driver can choose the gear independently to avoid automatic frequent gear shifting of the gearbox. It is better to let the power be excessive than to let the power be insufficient and drag the gear. Never slide in neutral when going downhill, hang the gearbox in low gear, use engine braking to contain the speed, and the braking system is used for emergency and short-term deceleration to avoid braking failure caused by braking thermal recession; If the engine is overheated or the braking system is overheated, stop and rest in time, and then continue driving after the temperature drops.