What is a semi automatic?

brendy said:
BMW tiptronic is pretty good, makes traffic driving easy and still retains a bit of sportiness with the up/down nudges on the open road.
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Thats just an automatic. A semi auto still has a normal gearstick to select gears just no clutch pedal.
 
Actually, it's not. Its a semi as per the quote about gear boxes above.

An old school automatic is one where you had P, D, N, R and maybe 3,2,1 for gears for steep hills carrying load.

If you can up and down shift when you like through all the gears, it's a semi automatic. It's as simple as that.

A semi automatic will also allow computer intervention and change gear automatically if the engine is being redlined.

That BMW is what most people would class as semi
 
Lucero said:
Actually, it's not. Its a semi as per the quote about gear boxes above.

An old school automatic is one where you had P, D, N, R and maybe 3,2,1 for gears for steep hills carrying load.

If you can up and down shift when you like through all the gears, it's a semi automatic. It's as simple as that.
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I dont think it is that simple though because moderm auto boxes still use the same basic design as autos of old with bands in them and torque converters on the front, just the control these days lets you go up and down the gearbox(BMW market them as automatics not semi autos). A semi auto is like a DSG gearbox where its got normal gears in there that select and mesh the same as a manual box and the clutch is moved automatically.
 
PMKeates said:
For standard automobiles, a semi-automatic transmission is typically considered to be any transmission whereby you do not have to operate a clutch pedal. Whether the transmission itself is operating a clutch, or is a torque converter-based system, is besides the point :)
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This

Automatic has no option at all to change gears

Semi Automatic has the option to switch between manual and automatic. Whether or not they are connected to a clutch or torque converter is irrelevant

Think of a Peugeot 106 Automatic for example

No flappy paddles, and no option to change gear yourself. Just auto
 
Dandle said:
I dont think it is that simple though because moderm auto boxes still use the same basic design as autos of old with bands in them and torque converters on the front, just the control these days lets you go up and down the gearbox(BMW market them as automatics not semi autos). A semi auto is like a DSG gearbox where its got normal gears in there that select and mesh the same as a manual box and the clutch is moved automatically.
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Mercedes flappy paddle autos were still classed as semi automatics even though they had a torque converter.
 
I have never driven an automatic that you did not have control of which gear you are in, that goes back to auto boxes from the fifties. Traditional set-up of torque converters still allowed you to choose between L1, L2 and D which encompassed all three available forward gears.

The difference to me of a semi auto is that they don't have a torque converter, the gearbox is more along the lines of a manual but with an automatic clutch (or two).
 
Scanias have a semi auto box which can can click the gear stick left/right to change gear, but still has a clutxh pedal to set off with.
 
Dup said:
Scanias have a semi auto box which can can click the gear stick left/right to change gear, but still has a clutxh pedal to set off with.
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Indeed, and what a prat you feel when you jump out of a clutchless DAF into said Scania and forget it has a clutch..... :o:D
 
Ring Peace said:
The difference to me of a semi auto is that they don't have a torque converter, the gearbox is more along the lines of a manual but with an automatic clutch (or two).
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incorrect

mercedes AMG flappy paddle system has a torque converter, but is still classed as semi auto as it still has 1st, 2nd ,3rd, 4th,5th,6th gears etc..
not L1,L2,L3
 
MrLOL said:
incorrect

mercedes AMG flappy paddle system has a torque converter, but is still classed as semi auto as it still has 1st, 2nd ,3rd, 4th,5th,6th gears etc..
not L1,L2,L3
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Just because Mercedes call it semi auto does not make it so, you could put paddle shift controls onto any gearbox all it does is send a signal to the torque converter to change gear, the computer then decides if this is possible then it shifts then after four seconds the gear is changed, same as waggling a stick forward back up down side to side.

The difference comes when a torque converter is not present and some other form of changing gears is used without a manual clutch.

Actually just ignore my rambling and read Fox's post he may be a [blank] but he puts it succinctly.
 
=Cybergangster said:
The difference to me of a semi auto is that they don't have a torque converter, the gearbox is more along the lines of a manual but with an automatic clutch (or two).
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As far as our second car is concerned your absolutely correct.

We have a 2008 fiat Panda Dualogic, this has a normal gearbox with eloctro hydraulic gearshift & clutch all controlled by software. Surprisingly smoother than many other vehicles fitted with similar type system -i.e Smart cars

It has no clutch pedal & can be used manually by pushing the lever forwards or backwards to change gears, the engine speed is maintained whilst the clutch is in so there is no jerk whatsoever when dropping down approaching a junction etc. & the change is rapid & smooth.

In auto mode it does all the work for you but you can override at anytime by tapping the gearstick.
All in all it has all the benefits of normal auto but without the extra weight & we are well impressed.
 
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Look Fox has already posted the Law on here, if it has a torque converter it is not a semi-auto, the Merc's new "7G-Tronic" has a torque converter therefore the Merc is NOT a semi. Q.E.D.
 
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