Sequential gearshift.

[teatako]

how do they work? are F1, cambiocorsa, selespeed and softouch (smart´s gearchange) exactly the same in essence? can they be modified to shift quicker? would it be a mod to the controlling software or to the components? clutch upgrade to handle more violent gearchange perhaps?

[TVR IS KING]

Whats sequential exactly...
Not to sound like a noob, but I dont know what it is...and sequential means in order. Find me a gear shift that starts with gear 8.

[kko]

Sequential means that tow shift up you just pull the lever back, and to shift down you push it foward, no left or right, quite handy.

[Zytek_Fan]

yay for wikipedia!

Semi-automatic transmission, or clutchless manual transmission, is a system which uses electronic sensors, processors and actuators to do gear shifts on the command of the driver. This removes the need for a clutch pedal which the driver needs to depress before making a gear change, since the clutch itself is actuated by electronic equipment which can synchronise the timing and torque required to make gear shifts quick and smooth. The system was designed by European automobile manufacturers to provide a better driving experience, especially in cities where congestion frequently causes stop-and-go traffic patterns.

In standard mass-production automobiles, the gear lever appears similar to manual shifts, except that the shift stick only moves forward and backward to shift into higher and lower gears respectively, instead of the traditional H-pattern. The Bugatti Veyron uses this approach for its 7-speed transmission. In Formula One, the system is adapted to fit onto the steering wheel in the form of two paddles; depressing the right paddle shifts into a higher gear, while depressing the left paddle shifts into a lower one. Numerous road cars have inherited the same mechanism.

Hall effect sensors sense the direction of requested shift, and this input, together with a sensor in the gear box which senses the current speed and gear selected, feeds into a central processing unit. This unit then determines the optimal timing and torque required for a smooth clutch engagement, based on input from these two sensors as well as other factors, such as engine rotation, the Electronic Stability Program, air conditioner and dashboard instruments.

The central processing unit powers a hydro-mechanical unit to either engage or disengage the clutch, which is kept in close synchronization with the gear-shifting action the driver has started. The hydro-mechanical unit contains a servomotor coupled to a gear arrangement for a linear actuator, which uses brake fluid from the braking system to impel a hydraulic cylinder to move the main clutch actuator.

The power of the system lies in the fact that electronic equipment can react much faster and more precisely than a human, and takes advantage of the precision of electronic signals to allow a complete clutch operation without the intervention of the driver.

Historically, the first semi-automatic transmission which was marketed was the 1941 M4/Vacamatic Transmission by Chrysler. It was an early attempt at an automatic transmission that still required the use of a clutch, primarily to start and stop. Later, the Volkswagen Beetle came with an optional "Autostick", which was essentially a clutchless manual with three forward gears.

Drag Racers have their own type of clutchless manual transmissions. A Liberty is basically a manual transmission with no clutch, and is used in Pro Stock. The Lenco is a transmisson also used in drag racers. A Lenco is different than a Liberty because a Lenco uses planetary gears and requires a torque converter, like an automatic. Both transmissions can be manually shifted, or use an air shifter. However, they require a clutch to use when leaving off the line for traction. The Lenco uses separate levers to shift while the Liberty uses a single shifter hooked up to several levers.

Some variants of the system, such as Citroën's Sensodrive, allow the driver to select automatic mode, in which the processor takes responsibility for gear changes. The car then drives much like a standard automatic, including features such as kickdown. Selecting a gear (using either stick or paddles) will restore manual control.

Semi-automatic transmissions have also made its way into the truck and bus market in the early 2000s. Volvo offers its i-Shift on its heavier trucks and buses, while ZF Friedrichshafen AG markets its ASTronic system for buses and coaches. These gearboxes have a place in public transport as they have been shown to significantly reduce fuel consumption.

[TVR IS KING]

Awesome. My dads Ford Falcon has one of those. They call it "Sportstronic".
Ive also heard it called "tiptronic". Everyone wants to sound unique...

[F1_Master]

I'm not sure, but I think tiptronic is Audi, but I could be wrong.
Nevertheless, these transmissions have been praised, espcially VW/Audi's as R&T and C/D have stated quite a few times the speed of the shifts are impossible to be obtained by human hand.

[Cyco]

Awesome. My dads Ford Falcon has one of those. They call it "Sportstronic".
Ive also heard it called "tiptronic". Everyone wants to sound unique...

Your father does not have a sequential 'box. He has an auto that allows him to override the computers prefered gear selection.

[TVR IS KING]

Really...?
What I know is its called sportstronic and, as well as auto mode, he can flick the lever to the side for a manual mode.

[Wouter Melissen]

Really...?
What I know is its called sportstronic and, as well as auto mode, he can flick the lever to the side for a manual mode.

It's an automatic gearbox with an option to override the computer. It is not like the Ferrari gearbox, which is an automatic clutch, but requires the driver to change the gears. There is a huge difference. By the time your dad's gearbox makes one change, the Ferrari's gearbox will have gone through the gears and back.

EDIT: Read the above again before making a post. Maybe twice.

[Quiggs]

So do sequentials use constant mesh gears like a manual tranny or clutch packs like a slush box?

[ruim20]

i know some types of gearboxes - i'll probably be wrong about something so please tell what you know so i can learn

Autos - and Autos with override like Wouter Melissen said

Manuals with clutch pedal - and Manuals without clutch pedal (like the Twingo Easy that used electronics to engage the clutch automaticly)

Sequentials - that use a + - sign to change gears and the gearchanging is made by an electro-hidraulic system (engaging the gear and clutch) some can also be used as a complete Auto.

DSG - Direct Shift GearBox - it's used in VW group cars and uses two clutches in the same gearbox, 1 clutch for 1st, 3rd, 5th gears and another clutch for 2nd, 4th and 6th gears, while you are driving the gearbox already as the next gear engaged, so when you ask for it it simply realeases the 1st gear clutch and engages the 2nd gear clutch and so on for the next gears. Can also be used in Auto mode.

Other sequentials like in some Touring cars or motorbikes change gear up directly but require the clutch to shift down - this is done completly mechanical.

[magracer]

From howstuffworks.com:

Advantages

"Nearly every race car that has a manual transmission uses the sequential approach rather than the "H" pattern. There are four main reasons for this preference:

- The sequential shift is quicker. For example, to go from 2nd to 3rd gear on the "H" pattern, you have to push the lever up, over and up again. That takes time. On a sequential gearbox, you simply push the lever up for every gear change.

- The sequential shift is consistent. You do not have to think, "Let's see, I'm in second gear so I have to go up-over-up to get to third." You simply push the lever forward -- it's the same motion for every gear.

- The hand location is consistent. With the "H" pattern, the location of the shift lever changes, so you have to think about where to put your hand depending on which gear you are in. With a sequential gearbox, the shift lever is always in the same place for the next shift.

- The sequential shift has no surprises. If you mis-shift with the "H" pattern in a race (for example, down-shifting to 2nd when you meant to go to 4th), it is possible to blow up the engine. That can never happen with a sequential gearbox.

- The other advantage is that the sequential shift lever takes up less space in the race car cockpit. You only need space for the forward/backward motion of the lever, not left/right."

"Because of the advantages of the sequential approach, this type of transmission is starting to appear on cars in the high-end tuner market. A sequential manual transmission is not to be confused with a "tiptronic" sort of automatic transmission. The tiptronic system may duplicate the shift lever motion of a sequential gearbox. However, because a tiptronic transmission is an automatic transmission at its core, it still has the torque converter and usually does not shift as quickly."

In a nut shell, a sequential manual transmision is basically what all motorcycles have.

Complete link:

http://auto.howstuffworks.com/sequential-gearbox1.htm

[zeppelin]

As technologically impressive as they are, I'll take a good ol' fashioned manual transmission any day.

[KnifeEdge_2K1]

manual transmission (any transmission which involves MANUAL operation of the clutch)
there's the standard manual transmission and the sequential transmission which translates updown movement of the gear lever to go between gears making it impossible to skip a gear or shifting into the wrong gear, i dont feel like explaining how it works but it involves a ratcheting drum

semi autos which involve tiptronic, steptronic, sports tronic, etc are simply auto slush boxes with an option to overide the pre programmed shift points and stuff letting you have a little bit more control of the car, its important to note that the computer still wont allow downshifts if they deem the new rpm as too high and will automatically shift up for you if you forget to (some may deem this as safe features but its just plain annoying) the most important difference between this and a regular manual is that semi autos still use a torque converter which gives crappy response and very little engine braking, definetly not for someone who has performance in mind

semi manuals are manual gearboxes with an electronically activated clutch

the dsg is a new gearbox which is basically 2 transmissions, one side has the odd numbered gears and the 2nd side has the even numbered gears and when you're in one side it preselects the next gear on the second side and makes the shift smoother and quicker, but it is much heavier then a regular transmission and although I dont know it as a fact i'm guessing packaging may be a very difficult issue to get around

[fpv_gtho]

its important to note that the computer still wont allow downshifts if they deem the new rpm as too high and will automatically shift up for you if you forget to (some may deem this as safe features but its just plain annoying)

Those are limitations inbuilt by the manufacturer, not the overall design of the transmissions. There are many examples of tiptronic auto's that will hold a gear at redline, and at the other end of the scale, at 500rpm...