Editing Direct-shift gearbox (section)

==Operational introduction==
The [[internal combustion engine]] drives two [[clutch]] packs.<ref name=VMS/><ref name=DCTfactsHow/> The outer clutch pack drives gears 1, 3, 5<ref name=VMS/> (and 7 when fitted), and reverse<ref name=VMS/> – the outer clutch pack has a larger diameter compared to the inner clutch, and can therefore handle greater torque loadings. The inner clutch pack drives gears 2, 4, and 6.<ref name=VMS/> Instead of a standard large dry single-plate clutch, each clutch pack for the six-speed DSG is a collection of four small wet interleaved clutch plates (similar to a [[motorcycle]] wet multi-plate clutch). Due to space constraints, the two clutch assemblies are [[concentric]], and the shafts within the gearbox are hollow and also concentric.<ref name=DCTfactsHow/> Because the alternate clutch pack's gear-sets can be pre-selected<ref name=VMS/><ref name=DCTfactsHow/> (predictive shifts enabled via the unloaded section of the gearbox), un-powered time while shifting is avoided<ref name=VMS/><ref name=DCTfactsHow/> because the transmission of torque is simply switched from one clutch-pack to the other.<ref name=VMS/> While the DSG has one of the fastest [[shift time]]s on the market, the claim that the DSG takes only about 8&nbsp;[[millisecond]]s to upshift is un-proven with 3-party data nor claimed by the manufacturer.

The variant of DSG fitted to [[PHEV|plug-in hybrid]] vehicles (such as the Golf/Passat GTE and the Audi A3 e-tron) also have a third clutch - its function is connect the electric motor to the combustion engine when both power sources are required simultaneously to propel the vehicle (the motor armature permanently turns with the input shaft of the transmission) - it also is engaged to [[Push start|bump start]] the combustion engine from the electric motor whenever the transmission is in the "N" position - this is due to the engine not having a conventional [[starter motor]].

===DSG controls===
The direct-shift gearbox uses a floor-mounted [[gear stick|transmission shift lever]], very similar to that of a conventional automatic transmission.<ref name=DCTfactsGolfPlus/> The lever is operated in a straight 'fore and aft' plane (without any '[[dog leg gearbox|dog-leg]]' offset movements), and uses an additional button to help prevent an inadvertent selection of an inappropriate shift lever position.

==== P ====
'''P''' position of the floor-mounted gear shift lever means that the transmission is set in [[parking pawl|park]].  Both [[clutch]] packs are fully disengaged, all [[gear train|gear-sets]] are disengaged, and a solid mechanical transmission lock is applied to the crown wheel of the DSG's internal [[differential (mechanical device)|differential]].  This position must only be used when the [[motor vehicle]] is [[:wikt:stationary|stationary]].  Furthermore, this is the position which must be set on the shift lever before the vehicle [[key (lock)#Car key|ignition key]] can be removed.

==== N ====
'''N''' position of the floor-mounted shift lever means that the transmission is in [[Transmission (mechanics)|neutral]]. Similar to '''P''' above, both clutch packs and all gear-sets are fully disengaged; however, the parking lock is also disengaged.

==== D mode====
Whilst the motor vehicle is stationary and in neutral ('''N'''), the [[driving|driver]] can select '''D''' for drive (after first pressing the foot [[brake]] [[automobile pedal|pedal]]). The transmission's outer clutch K2 engages at the ''start'' of the bite point, while on the alternate gear shaft the reverse gear clutch K1 is also selected.<ref name=VMS/><ref name=AboutCars/> The clutch pack for second gear (K2) gets ready to engage. When the driver releases the brake pedal, the K2 clutch clamping force is increased, allowing the transmission to drive the wheels. Depressing the [[throttle|accelerator]] pedal engages the clutch and causes an increase of forward vehicle speed. Pressing the throttle pedal to the floor (hard acceleration) will cause the gearbox to "kick down" to first gear to provide the acceleration associated with first, although there will be a slight hesitation while the gearbox deselects second gear and selects first gear. As the vehicle accelerates, the transmission's computer determines when the second gear (which is connected to the second clutch) should be fully used. Depending on the vehicle speed and amount of engine power being requested by the driver (determined by the position of the throttle pedal), the DSG then up-shifts. During this sequence, the DSG disengages the first outer clutch whilst simultaneously engaging the second inner clutch<ref name=VMS/><ref name=AboutCars/> (all power from the engine is now going through the second shaft), thus completing the shift sequence. This sequence in a fraction of a second (aided by pre-selection), and can be performed without lifting off the throttle, resulting in minimal power loss.<ref name=VMS/>

Once the vehicle has completed the shift to second gear, the first gear is immediately de-selected, and third gear is pre-selected.<ref name=VMS/><ref name=AboutCars/> Once the time comes to shift into 3rd, the second clutch disengages and the first clutch re-engages.<ref name=VMS/> This sequence repeats through the gear changes.

Downshifting is similar to up-shifting but in reverse order. At 600&nbsp;milliseconds downshifting is necessarily slower, due to the engine's [[Electronic Control Unit]] (ECU) needing to 'blip' the throttle so that the engine [[crankshaft]] speed can match the appropriate gear shaft speed.<ref name=VMS/> A downshift occurs when the ECU senses the car slowing down, or when more power is required.

The actual shift points are determined by the DSG's transmission ECU, which controls a hydro-mechanical unit.<ref name=VMS/> The transmission ECU, combined with the hydro-mechanical unit, are collectively called a ''[[mechatronics]]''<ref name=VMS/> unit or module. Because the DSG's ECU uses [[fuzzy logic]], the operation of the DSG is said to be ''adaptive'';{{dubious|date=July 2013}} that is, the DSG will "learn" how the user drives the car, and will progressively tailor the shift points accordingly to suit the habits of the driver.{{citation needed|date=July 2013}}

In the vehicle instrument display, between the [[speedometer]] and [[tachometer]], the available shift-lever positions are shown, the current position of the shift-lever is highlighted (emboldened), and the current gear ratio in use is also displayed as a number.

Under "normal", progressive and linear [[acceleration]] and deceleration, the DSG shifts in a [[sequential gearbox|sequential]] manner; i.e., under acceleration: 1st → 2nd → 3rd → 4th → 5th → 6th, and the same sequence reversed for deceleration. However, the DSG can also skip the normal sequential method, by missing gears, and shift two or more gears.<ref name=AboutCars/> This is most apparent if the car is being driven at sedate speeds in one of the higher gears with a light throttle opening, and the accelerator pedal is then pressed down, engaging the ''[[kick-down]]'' function. During kick-down, the DSG will skip gears,<ref name=DCTfactsGolfPlus/> shifting directly to the most appropriate gear depending on speed and throttle opening. This kick-down may be engaged by any increased accelerator pedal opening, and is completely independent of the additional resistance to be found when the pedal is pressed fully to the floor, which will activate a similar kick-down function when in Manual operation mode. The seven-speed unit in the 2007 Audi variants will not automatically shift to 6th gear; rather, it stays at 5th to keep power available at a high RPM while cruising.{{citation needed|date=July 2013}}

When the floor-mounted gear selector lever is in position '''D''', the DSG works in fully automatic mode,<ref name=AboutCars/><ref name=DCTfactsHow/> with emphasis placed on gear shifts programmed to deliver maximum [[fuel economy in automobiles|fuel economy]].<ref name=AboutCars/><ref name=DCTfactsGolfPlus/> That means that shifts will change up and down very early in the rev-range. As an example, on the [[Volkswagen Golf Mk5#Mk5 GTI|Volkswagen Golf Mk5 GTI]], sixth gear will be engaged around {{convert|52|km/h|mph|abbr=on}}, when initially using the DSG transmission with the default ECU adaptation; although with an "aggressive" or "sporty" driving style, the adaptive shift pattern will increase the vehicle speed at which sixth gear engages.

==== S mode ====
The floor selector lever also has an '''S''' position.<ref name=VMS/> When '''S''' is selected, sport mode<ref name=VMS/> is activated in the DSG. Sport mode still functions as a fully automatic mode,<ref name=AboutCars/> identical in operation to '''D''' mode, but upshifts and downshifts are made much higher up the engine rev-range.<ref name=VMS/><ref name=AboutCars/><ref name=DCTfactsGolfPlus/> This aids a more sporty driving manner,<ref name=VMS/> by utilising considerably more of the available [[Power (physics)|engine power]], and also maximising [[engine braking]]. However, this mode does have a detrimental effect on the vehicle [[fuel consumption]], when compared to '''D''' mode. This mode may not be ideal to use when wanting to drive in a sedate manner; nor when road conditions are very slippery, due to ice, snow or torrential rain – because loss of tire traction may be experienced (wheel spin during acceleration, and may also result in road wheel locking during downshifts at high engine rpms under closed throttle). On 4motion or quattro-equipped vehicles this may be partially offset by the drivetrain maintaining full-time engagement of the rear differential in S mode, so power distribution under loss of front-wheel traction may be marginally improved.

'''S''' is highlighted in the instrument display, and like '''D''' mode, the currently used gear ratio is also displayed as a number.

==== R ====
'''R''' position of the floor-mounted shift lever means that the transmission is in reverse.  This functions in a similar way to '''D''', but there is just one reverse gear. When selected, '''R''' is highlighted in the instrument display.

====Manual mode====
Additionally, the floor shift lever also has another plane of operation, for '''manual'''<ref name=AboutCars/><ref name=DCTfactsHow/> mode, with spring-loaded '''+''' and '''−''' positions. This plane is selected by moving the stick away from the driver (in vehicles with the driver's seat on the right, the lever is pushed to the left, and in [[left-hand drive]] cars, the stick is pushed to the right) when in '''D''' mode only. When this plane is selected, the DSG can now be controlled like a [[manual transmission|manual gearbox]], albeit only under a [[sequential manual transmission|sequential shift pattern]].

In most (VW) applications, the readout in the instrument display changes to '''6 5 4 3 2 1''', and just like the automatic modes, the currently used gear ratio is highlighted or emboldened. In other versions (e.g., on the Audi TT) the display shows just '''M''' followed by the gear currently selected; e.g., '''M1''', '''M2''', etc.

To change up a gear, the lever is pushed forward (against a spring pressure) towards the '''+''', and to change down, the lever is pulled rearward towards the '''−'''. The DSG transmission can now be operated with the gear changes being (primarily) determined by the driver. This method of operation is commonly called ''[[tiptronic]]''.<ref name=VMS/> In the interests of engine preservation, when accelerating in Manual/tiptronic mode, the DSG will still automatically change up just before the [[redline]], and when decelerating, it will change down automatically at very low revs, just before the engine [[idle speed]] (tick-over). Furthermore, if the driver calls for a gear when it is not appropriate (e.g., requesting a downshift when engine speed is near the redline) the DSG will not change to the driver's requested gear.<ref name=AboutCars/>

Current variants of the DSG will still downshift to the lowest possible gear ratio when the [[kick-down]] button is activated during full throttle whilst in manual mode. In Manual mode this kick-down is only activated by an additional button at the bottom of the accelerator pedal travel; unless this is pressed the DSG will not downshift, and will simply perform a full-throttle acceleration in whatever gear was previously being utilised.

=====Paddle shifters=====
Initially{{when|date=January 2022}} available on certain{{example needed|date=January 2022}} high-powered{{quantify|date=January 2022}} cars, and those with a "sporty"{{explain|date=January 2022}} trim level—such as those using the 2.0&nbsp;[[turbocharger|T]] [[gasoline direct injection|FSI]] and 3.2/3.6&nbsp;[[VR6 engine|VR6]] engines<ref name=VMS/>—[[steering wheel]]-mounted '''paddle shifters'''<ref name=AboutCars/><ref name=DCTfactsHow/> were available. However, these are now being offered (either as a standard inclusive fitment, or as a factory optional extra) on virtually all DSG-equipped cars, throughout all model ranges, including lesser power output applications, such as the 105&nbsp;PS [[Volkswagen Golf Mk5#Golf Plus|Volkswagen Golf Plus]].<ref name=DCTfactsGolfPlus/>

These operate in an identical manner as the floor mounted shift lever when it is placed across the gate in manual mode. The paddle shifters have two distinct advantages: the driver can safely keep both hands on the steering wheel when using the Manual/tiptronic mode; and the driver can temporarily [[manual override|manually override]] either of the automatic programmes ('''D''' or '''S'''),<ref name=DCTfactsGolfPlus/> and gain instant manual control of the DSG transmission<ref name=DCTfactsGolfPlus/> (within the [[#Manual mode|above]] described constraints).

If the paddle-shift activated manual override of one of the automatic modes ('''D''' or '''S''') is used intermittently the DSG transmission will default back to the previously selected automatic mode after a predetermined duration of inactivity of the paddles, or when the vehicle becomes stationary. Alternatively, should the driver wish to immediately revert to fully automatic control, this can be done by activating and holding the '''+''' paddle<ref name=DCTfactsGolfPlus/> for at least two seconds.