Twin Clutch SST
Encyclopedia
Twin Clutch SST is the brand name of a six-speed dual clutch transmission
developed by Getrag
for Mitsubishi Motors
. The system was first incorporated in the 2008 Lancer Evolution X
, and was designed to be a more performance-oriented system than that developed by rival manufacturers, with shorter gear ratios optimized for acceleration.
es to change gears. The TC-SST completes the clutch and gear shifts more quickly than a driver could in a conventional manual transmission
, and is also quicker than either an automatic transmission
with a torque converter
, or a single clutch automated manual transmission. The system's high-efficiency power transmission mechanism is on par with a normal manual gearbox, while allowing quicker gear shift
ing with no drop-off in engine power, thus offering greater performance
and better fuel economy
. The system can be operated by both a console-mounted shifter, and magnesium
steering wheel
paddle shifters; and offers semi-manual and fully automatic modes. TC-SST also works in conjunction with Mitsubishi's S-AWC system.
The operation of TC-SST is smoother than that of a conventional automatic transmission because it uses clutches instead of a torque converter
to transmit power. The key to the system's operation is in the electronic
and hydraulic controls. TC-SST can select two gears at the same time by putting odd (1st, 3rd, 5th) and even (2nd, 4th and 6th) gears on separate input shafts, each connected to an individual clutch. While one gear is engaged by one of the two electro-hydraulically operated wet multi-plate clutches, the other is pre-selected, awaiting to be engaged by the second wet multi-plate clutch. The TC-SST, in principle, behaves like two three-speed manual transmissions operating on the same output shaft. With both clutches under precise system control, the gear change is made when the clutches are "swapped" simultaneously, allowing fast, smooth gear changes with no interruption in power delivery. Nevertheless, those who prefer the traditional "stick shift" have criticized the level of driver involvement in TC-SST and other dual-clutch transmissions.
The odd and even gear shafts are linked via a transfer gear
, resulting in a shorter overall transmission length. The transmission electronic control unit
(ECU), sensors and solenoids are all housed within the transmission valve
body. The TC-SST is equipped with a transmission oil cooler
, and uses a unique fully synthetic transmission fluid developed by Castrol
for MMC called DiaQueen SSTF-I.
is required; and "S-Sport", which keeps the engine turning at even higher revs compared to "Sport". "Launch control
" is also available only in "S-Sport" mode.
Dual clutch transmission
A dual clutch transmission, commonly abbreviated to DCT , is a differing type of semi-automatic or automated manual automotive transmission. It utilises two separate clutches for odd and even gear sets...
developed by Getrag
Getrag
Getrag is a leading manufacturer of automobile manual transmissions. The company was founded on 1 May 1935, in Ludwigsburg, Germany, by Hermann Hagenmeyer; as the Getriebe und Zahnradfabrik Hermann Hagenmeyer GmbH & Cie KG...
for Mitsubishi Motors
Mitsubishi Motors
is a multinational automaker headquartered in Minato, Tokyo. In 2009 it was the fifth-largest Japan-based automaker and the 17th-largest in the world measured by production...
. The system was first incorporated in the 2008 Lancer Evolution X
Mitsubishi Lancer Evolution
The Mitsubishi Lancer Evolution, colloquially known as the Lancer Evo or Evo, is a high-performance sedan manufactured by Mitsubishi Motors. There have been ten official versions to date, and the designation of each model is most commonly a roman numeral...
, and was designed to be a more performance-oriented system than that developed by rival manufacturers, with shorter gear ratios optimized for acceleration.
Operation
TC-SST uses dual clutchClutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
es to change gears. The TC-SST completes the clutch and gear shifts more quickly than a driver could in a conventional manual transmission
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
, and is also quicker than either an automatic transmission
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
with a torque converter
Torque converter
In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load...
, or a single clutch automated manual transmission. The system's high-efficiency power transmission mechanism is on par with a normal manual gearbox, while allowing quicker gear shift
Gear shift
The gear shift is the part of the gearbox which has the shift forks and allows the contact from the driver to the synchronization. Most of the time they are so much like the gear counter plus the reverse gear. And they make it possible to choose the gear and to switch this in or out...
ing with no drop-off in engine power, thus offering greater performance
Performance
A performance, in performing arts, generally comprises an event in which a performer or group of performers behave in a particular way for another group of people, the audience. Choral music and ballet are examples. Usually the performers participate in rehearsals beforehand. Afterwards audience...
and better fuel economy
Fuel economy in automobiles
Fuel usage in automobiles refers to the fuel efficiency relationship between distance traveled by an automobile and the amount of fuel consumed....
. The system can be operated by both a console-mounted shifter, and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
steering wheel
Steering wheel
A steering wheel is a type of steering control in vehicles and vessels ....
paddle shifters; and offers semi-manual and fully automatic modes. TC-SST also works in conjunction with Mitsubishi's S-AWC system.
The operation of TC-SST is smoother than that of a conventional automatic transmission because it uses clutches instead of a torque converter
Torque converter
In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load...
to transmit power. The key to the system's operation is in the electronic
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
and hydraulic controls. TC-SST can select two gears at the same time by putting odd (1st, 3rd, 5th) and even (2nd, 4th and 6th) gears on separate input shafts, each connected to an individual clutch. While one gear is engaged by one of the two electro-hydraulically operated wet multi-plate clutches, the other is pre-selected, awaiting to be engaged by the second wet multi-plate clutch. The TC-SST, in principle, behaves like two three-speed manual transmissions operating on the same output shaft. With both clutches under precise system control, the gear change is made when the clutches are "swapped" simultaneously, allowing fast, smooth gear changes with no interruption in power delivery. Nevertheless, those who prefer the traditional "stick shift" have criticized the level of driver involvement in TC-SST and other dual-clutch transmissions.
The odd and even gear shafts are linked via a transfer gear
Transfer case
A transfer case is a part of a four-wheel-drive system found in four-wheel-drive and all-wheel-drive vehicles. The transfer case is connected to the transmission and also to the front and rear axles by means of drive shafts...
, resulting in a shorter overall transmission length. The transmission electronic control unit
Electronic control unit
In automotive electronics, electronic control unit is a generic term for any embedded system that controls one or more of the electrical systems or subsystems in a motor vehicle....
(ECU), sensors and solenoids are all housed within the transmission valve
Valve gear
The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle...
body. The TC-SST is equipped with a transmission oil cooler
Radiator
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...
, and uses a unique fully synthetic transmission fluid developed by Castrol
Castrol
Castrol is a brand of industrial and automotive lubricants which is applied to a large range of oils, greases and similar products for most lubrication applications...
for MMC called DiaQueen SSTF-I.
Drive modes
TC-SST allows switching between three shifting programmes: "Normal", which uses relatively low engine-speed shift points to deliver conservative shifting biased towards optimized fuel economy; "Sport", for use when driving in the mountains or when engine brakingEngine braking
Engine braking is where the retarding forces within an engine are used to slow a vehicle down, as opposed to using an external braking mechanism, for example friction brakes or magnetic brakes....
is required; and "S-Sport", which keeps the engine turning at even higher revs compared to "Sport". "Launch control
Launch control (automotive)
Launch control typically refers to an electronic aid which is used to assist the drivers of various motorsports at the start of a race.Launch control also refers to an electronic setting on many modern sporting saloons and coupes which help the driver accelerate from a standing start, to gain the...
" is also available only in "S-Sport" mode.
Gear ratios
| 1st | 2nd | 3rd | 4th | 5th | 6th | final |
|---|---|---|---|---|---|---|
| 3.655 | 2.368 | 1.754 | 1.322 | 1.000 | 0.775 | 4.062 |
Applications
- Mitsubishi Lancer Ralliart
- Mitsubishi Lancer Evolution X
- Mitsubishi OutlanderMitsubishi OutlanderThe Airtrek was first introduced to the Japanese market on June 20, 2001, priced from ¥1.7–2.3 million. It offered a choice of either a 4G63 2.0 L or a 4G64 2.4 L GDI, mated to a standard INVECS-II 4-speed semi-automatic transmission. Both front- and four-wheel drive were available...
/ Citroën C-Crosser / Peugeot 4007Peugeot 4007The Peugeot 4007 is a compact crossover SUV produced by the French automobile manufacturer Peugeot since July 2007.The equivalent Citroën badge-engineered version is the C-Crosser, both of which will be produced by Mitsubishi in its Nedcar plant, in Netherlands on the basis of the new Outlander...
External links
- Getrag Powershift 6DCT470 Transmission and Presskit, Getrag website
- "Twin Clutch-SST (Sport Shift Transmission) systematic", TC-SST schematic, .pdf file, Mitsubishi Motors North America press release