Semi Auto Gearbox
Discussion
There are really 4 different types of semi auto
1. An automatic gearbox with manual override, which can be manually shifted by either using a + or - shift on the gear lever, or in the case of my Mazda6 paddles on the steering wheel - as it's an auto, It can also be used as a conventional auto, and I guess is still really just an automatic transmission at the end of the day
2. DSG (or twin clutch) transmissions - these normally have 1st, 3rd, 5th and reverse on one shaft and controlled by clutch 1, then 2nd, 4th and 6th on a second shaft controlled by clutch 2 - gears are pre-selected by the transmission control module, and gear changes themselves are just a case of disengaging one clutch, whilst engaging the other - these can be shifted manually by use of paddles on the steering wheel, or by use of + or - on the lever, and can be driven in full auto mode.
If I was a betting man, I'd say that this where most manufacturers are investing there money, as they offer the best of both worlds, and VW (the pioneers of DSG) claim something like a 7% improvement in fuel economy and also lower emissions.
3. Automated manual transmissions - these are generally a conventional manual transmission, but the clutch is controlled by hydraulics and a computer, again, they generally have either paddles on the steering wheel, or + or - on the gear lever, and again, a full auto mode, all controlled by a transmission control module, which shifts with motors whilst controlling the the clutch.
4. Saab did a sensonic transmission - this was a conventional manual transmission, but the clutch was controlled by a control unit and hydraulic actuation - shifting required use of a manual lever just like in a normal manual, whilst the car operated the clutch - a clever idea, but not great to drive TBH. It monitored throttle position and gear lever movement to determine clutch operation.
Options 2, 3 and 4 have no clutch pedal, and full automatic modes, and can be driven on an automatic only driving licence
ETA: correction to the last bit - you wouldn't expect an auto to have a clutch pedal would you!!
1. An automatic gearbox with manual override, which can be manually shifted by either using a + or - shift on the gear lever, or in the case of my Mazda6 paddles on the steering wheel - as it's an auto, It can also be used as a conventional auto, and I guess is still really just an automatic transmission at the end of the day
2. DSG (or twin clutch) transmissions - these normally have 1st, 3rd, 5th and reverse on one shaft and controlled by clutch 1, then 2nd, 4th and 6th on a second shaft controlled by clutch 2 - gears are pre-selected by the transmission control module, and gear changes themselves are just a case of disengaging one clutch, whilst engaging the other - these can be shifted manually by use of paddles on the steering wheel, or by use of + or - on the lever, and can be driven in full auto mode.
If I was a betting man, I'd say that this where most manufacturers are investing there money, as they offer the best of both worlds, and VW (the pioneers of DSG) claim something like a 7% improvement in fuel economy and also lower emissions.
3. Automated manual transmissions - these are generally a conventional manual transmission, but the clutch is controlled by hydraulics and a computer, again, they generally have either paddles on the steering wheel, or + or - on the gear lever, and again, a full auto mode, all controlled by a transmission control module, which shifts with motors whilst controlling the the clutch.
4. Saab did a sensonic transmission - this was a conventional manual transmission, but the clutch was controlled by a control unit and hydraulic actuation - shifting required use of a manual lever just like in a normal manual, whilst the car operated the clutch - a clever idea, but not great to drive TBH. It monitored throttle position and gear lever movement to determine clutch operation.
Options 2, 3 and 4 have no clutch pedal, and full automatic modes, and can be driven on an automatic only driving licence
ETA: correction to the last bit - you wouldn't expect an auto to have a clutch pedal would you!!
Edited by Superhoop on Monday 7th October 20:46
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