DSG Transmissions
Contents
Page 1 Cover
Page 2 Contents
Page 3 History
Page 4 full Operation
Page 5, 6 & 7 Internal Components
Page 8 & 9 Disadvantages
Page 10 Advantages
Page 11 Where Information was Found
History
DSG history:
Porsche was the first company to invent DSG (Direct Shift Gearbox) more than 20 years ago. They stopped using DSG on their cars because of the significant power that their current models put out.
It was also said that the DSG was designed by Borg Warner & licensed to the Volkswagen Group.
Full Operation
DSG provides the driver with a far smoother ride with such easy gear changing on an automatic transmission.
This Trans is the first to have twin/ double clutches that allow an efficient gear change.
The DSG has 2 clutches, one for the even gears & one for the odd gears plus reverse.
One clutch is engage & the other one preselects the next gear, this allows a far faster change between gears. When the car is in 2nd gear the other clutch has 3rd selected but not engaged & soon as the RPMs are reached for the idle shift point then 3rd is so quickly if not instantly engaged.
This allows the DSG to have faster shift times.
Due to space being an issue the two clutch assemblies had to be concentric – this meaning one within the other.
Clutch two being hollowed out & holding clutch one inside of it.
Each clutch pack has 4 smaller clutch discs instead of the normal single large clutch plate found in most gearboxes. This allows the gear changing to be 8 milliseconds to upshift instead of hundreds of a second.
Internal Components
DSG is two separate manual gearboxes and clutches. This is all cased within one housing and works as one unit, by using two separate clutches.
The outer clutch drives gears 1, 3, 5 & reverse. This clutch is larger compared to the inner clutch & can handle bigger torque loadings.
The inner clutch drives 2, 4 & 6, also instead of a single plate clutch, on the six speed there are 4 small wet interleaved clutch plates.
A wet clutch plate has a cooling lubricant fluid which not only cools the clutch plates but also keeps the surfaces clean & helps with a smoother performance & also a longer life.
“P” – is understood better as (Park), When the transmission is selected to park. Both the clutch packs are all fully disengaged & a solid lock is applied to the parking gear/ planetary output.
Natural is the same as park but there is absolutely no gears selected what so ever.
“D” – Drive, when this gear is selected the outer clutch is engaged into 1stgear & the inner clutch has preselected 2nd, as the change in gears is made from 1st to 2nd, the outer clutch will then preselect 3rd & the inner clutch is already selected into 2nd.
4 shift forks, each shift fork controls a couple of gears.
1 x fork controls 2nd & 4th
1 x fork controls 1st & 3rd
1 x fork controls Reverse & 6th
1 x fork controls 5th
2 x input shafts & a reverse idler
1 input shaft that consist of 2, 4 & 6 gears & the other input shaft consist of 1, 3, 5 & Reverse. Instead of having 3 synchronisers to a 5 gear system, there are 4 to this 6 gear system. 5th gear having its own synchroniser & shift fork.
Disadvantages
It is said by one critic that the DSG is heavier than an ordinary transmission, manual or normal automatic. They have higher replacement costs, lower reliability.
The DSG should also provide better performance on the TDI, but being a heavier transmission the power loss take away performance compared to other transmissions.
In 2009 & 2010 the VW Audi DSG S – Tronic recalled the temp sensor for some of the models of their cars that were made in between September & August 2009. A faulty temp sensor can result in dashboard lights flicking on & off, also the transmission can shift out of drive, staying in neutral & not shifting back.
The main problems I could find were due to the transmission being heavier & more expensive overall – Mechanically & on the oils & lubricants.
Also if you wanted to change down gear while hill climbing the RPMs have to be higher than 3000 or 4000 RPM, to be able to trigger the kick down switch.
Hans has also found the following disadvantages:
The main limitation of the twin-clutch/DSG is the same as all geared transmissions: Because there are a fixed number of gears, and the transmission cannot always keep the engine at its best speed for maximum power or maximum fuel economy. Because of this, twin-clutch transmissions generally cannot extract as much power or fuel economy from an engine as a continuously-variable automatic transmissions (CVTs). But because twin-clutch transmissions provide a more familiar driving experience than CVTs, most drivers prefer them. And while the twin-clutch provides superior performance compared to a manual, some drivers prefer the interaction that a manual clutch pedal and gearshift provide.
Advantages
Short up shift times of 8 milliseconds, when shifting into a gear that has been preselected. This also makes the gear shifting run a lot smoother.
There is no loss of torque from the transmission to the engine then from the engine to the wheels, during the gear shifting.
Being able to shift gears faster this also gives the car faster throttle response & lively handling with unbroken acceleration.
It gives you safer driving with the power to get you out of a tricky situation.
Improved fuel economy even compared to a manual gearbox.
Where information was located
All information was found on the following sites:
Ehow
Wikipedia
Audi
VW
About cars
I used Google to find all of these sites
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