How does an automatic gearbox work?
Wednesday 11th September 2024
Many car manufacturers offer automatic gearboxes, but differentiating between the different types of automatic gearboxes available can be overwhelming. While a manual gearbox allows you to choose the gear you want to be in via the clutch and gear stick, an automatic gearbox uses hydraulic power to change gears automatically.
This article looks at how an automatic gearbox works.
What is an automatic gearbox?
An automatic gearbox allows your car to change gears without a clutch pedal. All automatics have an accelerator and brake pedal and will shift gears automatically in response to the driver accelerating or braking.
What components make up an automatic gearbox?
Typically, an automatic gearbox consists of the following parts:
- Torque converter
- Bell housing
- Planetary gears
- Brake clutches and bands
- Output shaft
- Oil pump
The differences between an automatic and manual gearbox
There are many differences between an automatic and manual gearbox to consider when upgrading your car:
- An automatic is well-suited for busy city streets and rush hour traffic.
- A manual offers more control when driving in variable weather conditions (ice, snow and rain).
- Automatic gearboxes are easy to use as you don’t need to shift gears.
- A manual gearbox allows you to ‘engine’ brake by changing to a lower gear rather than relying on the brake pedal.
What types of automatic gearboxes are available?
Automatic gearboxes come in many types, including:
- Automated manual gearbox - Automated manual gearboxes work like a traditional manual, but the electric control unit controls how your car changes gears. With an automated manual, you can only activate Reverse and Drive via the gear stick.
- Continuous variable transmission – CVT is a type of automatic gearbox which doesn’t use gears but belts to select the right gear when driving. Many hybrids use a CVT gearbox as it provides a better workload balance with the electric motor and petrol engine.
- Dual-clutch transmission – DCT gearboxes have much in common with automated manual gearboxes. However, a dual-clutch gearbox has two clutches, one for odd gears and another for even gears. Most vehicles with a dual-clutch transmission allow you to change gears automatically or by yourself.
- Single-speed gearbox – All EVs have a single-speed gearbox, meaning there is a single gear which transfers the power from the electric motor to the wheels.
The advantages of an automatic gearbox
Driving an automatic vehicle has many advantages:
- An automatic gearbox delivers more power than a manual.
- Automatics are environmentally friendly, with most EVs and hybrids having an automatic gearbox.
- You won’t stall when driving an automatic.
- An automatic gearbox has excellent resale value.
Should I take my driving test in a vehicle with an automatic gearbox?
Manual or automatic? Deciding whether to take your driving test with an automatic or manual is a matter of personal preference. If you live in a hilly or high-traffic area, passing your test with an automatic will offer an easier and more comfortable driving experience.
Can I drive an automatic if I have learned to drive a manual car?
Yes. If you have passed your driving test in a manual, you can drive both automatic and manual vehicles, but if you passed your test in a vehicle with an automatic gearbox, you cannot drive a car with a manual gearbox without resitting your driving test.
Understanding how an automatic gearbox works gives you the information needed to upgrade your car. Are you struggling to change gears with your vehicle? Our guide covers why your car struggles to change gears. Does your automatic car need repairing or servicing? Book your annual MOT or service at your local Formula One Autocentres branch today.
