How does a automated manual gearbox interface with the clutch?

[Howard]

Obviously an engine cannot be stalled and run normally, so a clutch lets it idle. How does the computer/transmission handle the transition from very slow or stopped, to first gear and back again?

e.g. if I'm at a red light and I go, the clutch goes in with first gear selected. How does the driver see this and what is actually happening inside?

 

[Pantoot]

Obviously an engine cannot be stalled and run normally, so a clutch lets it idle. How does the computer/transmission handle the transition from very slow or stopped, to first gear and back again?

e.g. if I'm at a red light and I go, the clutch goes in with first gear selected. How does the driver see this and what is actually happening inside?

With BMW's SMG the clutch disengages when the gas is pressed. The brakes will hold for a few seconds so you don't roll if you are on a hill.

In practice it works well most of the time.

 

[soccerballtux]

With BMW's SMG the clutch disengages when the gas is pressed. The brakes will hold for a few seconds so you don't roll if you are on a hill.

In practice it works well most of the time.

- .-

 

[NutBucket]

And that's why the SMG was not well liked

 

[LTC8K6]

"dual clutch"...

 

[Pantoot]

It can be a bit jerky in stop and go traffic, especially if you "surprise" it by hitting the gas, brake, gas. (like the light turns green traffic moves a foot but the guy at the front of the line doesn't move)

When you are moving it is jerky for a whole different reason, in S6 it can feel like you are rear ended it shifts so hard.

 

[soccerballtux]

It can be a bit jerky in stop and go traffic, especially if you "surprise" it by hitting the gas, brake, gas. (like the light turns green traffic moves a foot but the guy at the front of the line doesn't move)

When you are moving it is jerky for a whole different reason, in S6 it can feel like you are rear ended it shifts so hard.

that's what I've noticed as well

 

[TheHashmaster]

And that's why the SMG was not well liked

+1

SMG I and II were doodoo, dual clutch is where its at.

 

[Howard]

+1

SMG I and II were doodoo, dual clutch is where its at.

How does dual clutch solve this issue? Only one clutch can be engaged at a time anyway.

 

[Spicedaddy]

Obviously an engine cannot be stalled and run normally, so a clutch lets it idle. How does the computer/transmission handle the transition from very slow or stopped, to first gear and back again?

e.g. if I'm at a red light and I go, the clutch goes in with first gear selected. How does the driver see this and what is actually happening inside?

When you put it in Drive or Manual mode, it'll actually slip the clutch very slightly in 1st gear even when you're stopped. That's why it automatically goes forward when you let go of the brake and don't touch the gas pedal... It's also useful for parking, slow speed driving etc. VW calls it creep mode I think.

Same thing for Reverse. They basically act the same as a torque converter auto tranny.

 

[exdeath]

Pulse width modulation?

 

[Howard]

Pulse width modulation?

Pretty sure it would be analog control. Lots of inertia.

 

[Pantoot]

When you put it in Drive or Manual mode, it'll actually slip the clutch very slightly in 1st gear even when you're stopped. That's why it automatically goes forward when you let go of the brake and don't touch the gas pedal... It's also useful for parking, slow speed driving etc. VW calls it creep mode I think.

Same thing for Reverse. They basically act the same as a torque converter auto tranny.

With BMW's SMG once the hill assist turns off you will roll freely when the car is in 1st gear.