I’m a driving instructor from the UK who teaches automatic. I’ll try and keep this as brief as possible!
There are 3 main types of automatic gearbox: CVT, DCT, and ATM.
CVT (Continuously Variable Transmission)
CVTs don’t have traditional gears, but are based on a system which pulls and pushes on a belt to keep the engine in an optimal rev range. They have a torque converter which, when the car is in D (‘Drive’), will cause the car to want to pull forward. It’s the automatic equivalent of finding the bite. The power from the torque converter is often enough for most hills, but you may get some slight roll-back on some steeper hills. At this point, I often teach my learners to do a traditional hill start (handbrake up, slight pressure on the accelerator, handbrake down). On cars with electric handbrakes, I often find that these cars tend to have their own assisted hill start systems which prevent roll-back without needing to pull a handbrake.
You will find CVTs in an overwhelming majority of lower to mid class cars.
DCT (Dual-Clutch Transmission)
These have a huge variety of names depending on the brand, but all do very similar things. In a DCT you have traditional gears, but you also have two clutches; this is to make shifting seamless. When you accelerate, it readies the next higher gear so that when it’s ready to change it will do so instantaneously. When you’re pressing the brake, it will ready the next lower gear and shift down seamlessly when ready. These vehicles also have a torque converter and work exactly as described above.
You’ll find DCTs in most mid to higher class cars.
AMT “Automated Manual Transmission”.
CVTs and DCTs are heavy, so in places like Europe and Japan where lightweight eco boxes rule the roads, an automatic gearbox doesn’t make a lot of sense (and is likely a big contributing factor as to why manual transmissions are more common in these places than in America). Ergo, the AMT was conceived. It takes a basic manual transmission, removes the clutch pedal and replaces it with a computer program which does all the leg work for you. It weighs basically the same as a manual transmission, it’s extremely cheap in comparison to the other two options, and vastly cheaper to repair. Sadly there are drawbacks, and one such drawback is that these don’t have torque converters.
So, what happens instead is that the clutch doesn’t ‘bite’ until you press the accelerator. This means that whilst you’re standing still, the car is free to roll with gravity, even if you’re in Drive! Even the slightest hill will have you rolling, making it imperative that you use the handbrake when you come to a stop.
As mentioned, you’ll tend to find AMTs in a lot of tiny eco boxes, especially older ones. A lot of modern cars which would have had AMTs are being built with CVTs instead.
Fun fact: I used to drive a 3.5 tonne Iveco van that had an AMT. It was bloody awful!
I’m talking about hills. Holding the brake is fine when you’re relatively level, but if you’re pointing up hill the car will roll back if it doesn’t have hill start assist.
I know most people will just hold brakes and move quickly towards the accelerator, but I’m an instructor as I mentioned; it’s a different ball game for learners. In test conditions if they try that and miss the pedal, they’ll roll back and will get a minor for rolling back, or even fail their test if the examiner has to stop them.
So yes, I teach them to use the handbrake because it’s much less stressful and less likely to lead to a mistake that will lead to panicking.
I’ve experienced a DCT with e-break and hill assist that stops the hill holder when pressing the accelerator even though the torque generated is not yet enough to actually keep the car from rolling back. This same car has a very twitchy accelator where, while on a hill it will not really react to pressing the accelerator until a certain tiny threshold is reached, at which point in shoots forward aggressively if you overshot the threshold.
As a result, on a hill while releasing the break, the car stays put, touching the accelerator gently to find the threshold will have you roll back hitting the car behind and pressing the accelerator harder to avoid this will have you lurch forward hitting the car in front. It’s never been a problem in traffic because you have time to react to these weird behaviours, but between very tightly parked cars, it is a nightmare.
I’m a driving instructor from the UK who teaches automatic. I’ll try and keep this as brief as possible!
There are 3 main types of automatic gearbox: CVT, DCT, and ATM.
CVTs don’t have traditional gears, but are based on a system which pulls and pushes on a belt to keep the engine in an optimal rev range. They have a torque converter which, when the car is in D (‘Drive’), will cause the car to want to pull forward. It’s the automatic equivalent of finding the bite. The power from the torque converter is often enough for most hills, but you may get some slight roll-back on some steeper hills. At this point, I often teach my learners to do a traditional hill start (handbrake up, slight pressure on the accelerator, handbrake down). On cars with electric handbrakes, I often find that these cars tend to have their own assisted hill start systems which prevent roll-back without needing to pull a handbrake.
You will find CVTs in an overwhelming majority of lower to mid class cars.
These have a huge variety of names depending on the brand, but all do very similar things. In a DCT you have traditional gears, but you also have two clutches; this is to make shifting seamless. When you accelerate, it readies the next higher gear so that when it’s ready to change it will do so instantaneously. When you’re pressing the brake, it will ready the next lower gear and shift down seamlessly when ready. These vehicles also have a torque converter and work exactly as described above.
You’ll find DCTs in most mid to higher class cars.
CVTs and DCTs are heavy, so in places like Europe and Japan where lightweight eco boxes rule the roads, an automatic gearbox doesn’t make a lot of sense (and is likely a big contributing factor as to why manual transmissions are more common in these places than in America). Ergo, the AMT was conceived. It takes a basic manual transmission, removes the clutch pedal and replaces it with a computer program which does all the leg work for you. It weighs basically the same as a manual transmission, it’s extremely cheap in comparison to the other two options, and vastly cheaper to repair. Sadly there are drawbacks, and one such drawback is that these don’t have torque converters.
So, what happens instead is that the clutch doesn’t ‘bite’ until you press the accelerator. This means that whilst you’re standing still, the car is free to roll with gravity, even if you’re in Drive! Even the slightest hill will have you rolling, making it imperative that you use the handbrake when you come to a stop.
As mentioned, you’ll tend to find AMTs in a lot of tiny eco boxes, especially older ones. A lot of modern cars which would have had AMTs are being built with CVTs instead.
Fun fact: I used to drive a 3.5 tonne Iveco van that had an AMT. It was bloody awful!
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“use the handbrake when you come to a stop”
What the fuck are you talking about? Just hold the brake pedal.
I’m talking about hills. Holding the brake is fine when you’re relatively level, but if you’re pointing up hill the car will roll back if it doesn’t have hill start assist.
I know most people will just hold brakes and move quickly towards the accelerator, but I’m an instructor as I mentioned; it’s a different ball game for learners. In test conditions if they try that and miss the pedal, they’ll roll back and will get a minor for rolling back, or even fail their test if the examiner has to stop them.
So yes, I teach them to use the handbrake because it’s much less stressful and less likely to lead to a mistake that will lead to panicking.
I’ve experienced a DCT with e-break and hill assist that stops the hill holder when pressing the accelerator even though the torque generated is not yet enough to actually keep the car from rolling back. This same car has a very twitchy accelator where, while on a hill it will not really react to pressing the accelerator until a certain tiny threshold is reached, at which point in shoots forward aggressively if you overshot the threshold.
As a result, on a hill while releasing the break, the car stays put, touching the accelerator gently to find the threshold will have you roll back hitting the car behind and pressing the accelerator harder to avoid this will have you lurch forward hitting the car in front. It’s never been a problem in traffic because you have time to react to these weird behaviours, but between very tightly parked cars, it is a nightmare.