Transmission Layout
Porsche Doppelkupplung (PDK) Layout
The new Porsche Doppelkupplung (PDK) basically comprises a conventional manual transmission that has been split into two partial transmissions and a hydraulic control unit. At its core, the transmission has two multiple-disc clutches. One clutch is for the first transmission with the odd gear stages (1, 3, 5, 7) and the other clutch is responsible for the second transmission with the even gear stages and reverse gear (2, R, 4, 6). The hydraulic control unit uses a number of pressure valves to control both the multiple-disc clutches and the shift cylinders for engaging the desired gear ratio.
The particular feature of this transmission concept is that it provides a continuous flow of power between the engine and the final drive, even during a gear change. One of the two clutches is always closed in normal driving mode. The second clutch is open while the power is being relayed from the engine to the wheels via the first clutch and the first transmission; the next gear up or down will already be engaged in the second transmission depending on the driving situation and the shift strategy.
When changing gear, the first clutch opens as the second clutch simultaneously closes. Through this continuous and alternating gear change operation, the propulsion force, monitored by the engine, is changed over from one transmission to the other without any interruption in traction. In the PDK, the entire gear change itself involves complex fine tuning of the function processes between the two clutches and the gear stages of the individual transmissions.
The use of two clutches or transmissions makes it possible to execute gear changes smoothly without interrupting the traction. Rapid gear changes and short response times within just a few milliseconds are a further characterising feature of the Porsche Doppelkupplung (PDK). This is possible thanks to the principle of parallel gear preselection. The transmission control system assists here in preselecting and keeping ready the appropriate gear ratio for the particular driving state and driving situation in the inactive transmission.
Transmission Concept
The new Porsche Doppelkupplung (PDK) is noted for the following customer benefits:
- Much faster gear shifts with no noticeable interruption in traction due to rapid change-over of disengagement and engagement operations, rapid gear changes and short response times; this ensures greater agility and more driving pleasure
- Outstanding driving comfort because of gentle, automated clutch and shift operations
- Direct connection to the engine (without rubber-band effect of a torque converter)
- Outstanding drive dynamics due to a short 1st gear that changes rapidly to the preselected 2nd gear
- Direct and fast multiple downshifts with spontaneous power requirements
- Much greater range of functions such as the Launch Control function (with optional Sport Chrono Package Plus) and performance oriented shift operations with increased torque
- Lower fuel consumption and emissions thanks to the additional 7th gear and a total ratio spread of 10.1 with a significantly reduced rev range
- Reduction in fuel consumption and CO2 emissions through high overall efficiency and a simplified Start Stop function
- Reduction in system weight of approx. 33 lbs. (15 kg) compared to a conventional all-wheel automatic system
- Dual-mass flywheel for reducing vibration and noise
The Porsche Doppelkupplung (PDK) comprises 7 gears and 1 reverse gear. Gears 1 to 6 have a sporty tuning and top speed is reached in 6th gear. The total ratio spread between the 1st and 7th gear of the transmission is 10.1.
This efficient arrangement of gear increments is unique in the passenger car segment. Together with short 1st gear, it ensures outstanding drive-off dynamics. In contrast, the 7th gear has a very high ratio and this makes it possible to increase comfort when driving long distances and also to improve fuel economy through reduced engine speeds.
Porsche developed the Porsche Doppelkupplung (PDK) in the 1980s for motor sports. The fact that there was no interruption in traction when changing gears gave it the edge over competitor vehicles. Shorter shifting times were possible and this considerably increased the race car's acceleration. In addition to these benefits, the PDK in the Panamera also helps to improve driving comfort, efficiency and fuel consumption.
NOTE: Ratio spread is the gear ratio range of the transmission, i.e. the relationship between the largest gear ratio value and the smallest gear ratio value. This means that the transmission should use a crawling gear with a high gear ratio for very low speeds and a gear with a low gear ratio for overdrive mode.