Widely used in the market is Volkswagen's DSG series dual-clutch transmission. It mainly includes DSG-6-speed dual-clutch transmission and DSG-7-speed dual-clutch transmission. The parking brake lever DSG-6-speed dual-clutch transmission uses a "wet" dual clutch. "Wet" means that the dual clutch is installed in a closed oil chamber filled with hydraulic oil. The internal code of the DSG-6-speed wet dual-clutch transmission is DQ250. This wet structure has better adjustment capabilities and excellent heat capacity. Therefore, the maximum torque that can be withstood is 350N?m. The DSG-7-speed dual-clutch transmission uses a "dry" dual-clutch. The dual-clutch is composed of two clutch plates of similar size installed coaxially and stacked on each other, because its dual-clutch is not installed like the DSG-6-speed wet dual-clutch transmission. In a closed oil chamber, it is called a "dry" dual clutch. The internal code of the DSG-7-speed dry dual-clutch transmission is DQ200. The "dry" dual clutch has a simple structure and is therefore more efficient, but it is "dry". The inherent characteristics of the clutch's own structure enable it to withstand the maximum torque ratio.