The gearbox and its role in the car

Whether automatic transmission or manual gearbox, it is an important component in vehicles with a combustion engine. Without it, movement on the road and other surfaces would not be possible. It transmits the engine's power to the wheels to overcome rolling resistance, especially when starting off or accelerating. Use the following guide to find out more about how the gearbox works.

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What is a gearbox?

The gearbox is part of the drivetrain that makes it possible to move your car. It is made up of the following components:

• Engine
• Automatic transmission or manual transmission
• Clutch
• Driveshaft
• Axle differential

This applies to combustion vehicles that are fuelled with petrol or diesel.

In contrast, electric cars do not have a gearbox, as the electric motor has a much higher range of speeds and therefore, with a few exceptions, no gears are used.

What does the transmission do?

Regardless of whether it is an automatic gearbox, a dual-clutch gearbox or a manual gearbox: the main task is to convert the engine speed into the appropriate torque, depending on the driving situation, so that you as the driver can set your car in motion and accelerate. To enable this process, the transmission is connected to the existing drive shaft via a clutch. In vehicles with front or rear-wheel drive as well as all-wheel drive vehicles, this is a cardan shaft that ultimately transmits the power to the individual wheels on the axle.

What types of gearboxes are there?

Whether you prefer an automatic gearbox or a vehicle with manual transmission, where you select the gear yourself, depends on your personal preferences. In some cases, the topic is discussed as a question of faith, which is why we have summarised the different basic variants and their respective functions below. (The geared motor is not considered further here).

• Manual gearbox: This is a widespread variant. To interrupt the transmission of power from the engine to the gearbox via the clutch disc and the associated pressure plate, the clutch is operated manually using the pedal on the outside left of the driver's side. As the driver, you decide when to engage which gear and which torque is to be transmitted.
• Automatic transmission: The structure is comparable to the manual transmission. With automatic transmission, however, the gears are selected automatically depending on the driving situation. You can influence this by using the so-called kickdown if you want to accelerate your car more quickly. When you depress the accelerator pedal, the next lower gear is engaged; when you release it, the next higher gear is selected again.
• Continuously variable automatic transmission: Also known as a CVT transmission (Continuously Variable Transmission), the transmission is equipped with two friction discs (variators). This means that there is no interruption in tractive force during automated gear changes, as is the case with manual transmissions, as the transmission ratio is changed continuously. One of the major advantages is that the optimum torque is transmitted practically continuously.
• Dual clutch transmission: Depending on the manufacturer, this type of automated manual transmission is also known as a direct shift transmission (VW), S-Tronic (Audi) or double clutch transmission (Mercedes-Benz). Equipped with two clutches, it allows uninterrupted gear changes, as the next gear is always already engaged. One clutch is responsible for even gears and the other for odd gears in your car.

These are the most common manual and automatic gearboxes, which are installed depending on the vehicle class. If you opt for a vehicle with automatic transmission, you will have to pay a surcharge compared to a manual transmission. You can find out how much this is by checking the price details for the equipment or asking your dealer directly.

Other transmission types with their special mode of operation

In order to maintain the optimum torque in Nm (Newton metres) as permanently as possible, other variants are available, although these are somewhat less common. These include the following.

• Sequential transmission: In principle, this is a semi-automatic transmission. In contrast to a manual gearbox, you can only shift to the next higher or next lower gear in your car when changing gear. One of the typical representatives is the dual-clutch transmission with a slight interruption in traction.

This type of transmission originally comes from motorsport and is also used in the tuning sector through retrofitting. However, due to the higher force applied, the gearwheels must be expected to wear more quickly. In addition, a separate oil circuit with higher pressures is usually required to fulfil the requirements.

How do you secure your car with automatic transmission?

When switching from a manual gearbox to an automatic transmission, there are a few special features to bear in mind. Although there is a gear lever as usual, it does not display the gears but the functions in the form of letters:

• N stands for Neutral: you engage neutral.
• D stands for Drive: You want to move your vehicle.
• R stands for Reverse: You are engaging reverse gear.
• P stands for Parking: You are parking.

As soon as you have moved your vehicle into the park position, secure it with the mechanical handbrake or the electric parking brake. To start it, the gear lever must be in P and the brake must be applied, otherwise the engine will not start.

When is the transmission oil due for a change?

While the oil in the engine must be changed regularly, there is no binding recommended change interval for transmission oil. Depending on the mileage, consider a possible change after approx. 150,000 kilometres or after a period of 10 years at the latest.

As a driver, you should also think about changing your tyres in good time. Timely means that new tyres are due at the latest when the legally prescribed minimum tread depth of 1.6 mm is reached. At the very latest, you should replace your tyres after approx. 8 to 10 years. Use our easy-to-understand online configurator to find the right tyres for your car and order them from our shop at a reasonable price.

Use our easy-to-understand tyre search function to find the perfect new tyres for your car: