液力變矩器可以傳遞和增加發動機扭矩，但轉矩比不大，速度范圍不寬，遠遠不能滿足車輛運行工況的需要。變速箱維修價格是車輛上非常重要的部件，它可以改變傳動比，擴大驅動輪轉矩和轉速的作用。
Hydraulic torque converter can transfer and increase engine torque, but the torque ratio is small and the speed range is not wide, which is far from meeting the needs of vehicle operating conditions. Transmission maintenance price is a very important part of the vehicle. It can change the transmission ratio and expand the role of driving wheel torque and speed.
隨著現代科技的發展，變速箱也有了升級，從手動變速箱，到現在無級變速箱，從無同步器到有同步器，操控越來越方便。為了進一步提高扭矩，擴大其變速范圍，提高車輛的適應性，在液力變矩器后面安裝了輔助傳動裝置，并經常采用行星齒輪機構。
With the development of modern science and technology, the gearbox has also been upgraded. From manual gearbox to stepless gearbox, from no synchronizer to synchronizer, the operation is more and more convenient. In order to further improve the torque, expand its transmission range and improve the adaptability of the vehicle, an auxiliary transmission device is installed behind the hydraulic torque converter, and planetary gear mechanism is often used.
行星齒輪傳動由行星齒輪機構和離合器、制動器、單向離合器等執行機構組成。行星齒輪機構通常由多排行星組成。行星的數量取決于文件的數量。
Planetary gear transmission is composed of planetary gear mechanism and actuator such as clutch, brake and one-way clutch. Planetary gear units are usually composed of multiple rows of planets. The number of planets depends on the number of files.
行星齒輪傳動的換檔執行器包括換檔離合器、換檔制動器和單向離合器。
The shift actuator of planetary gear transmission includes shift clutch, shift brake and one-way clutch.
換檔離合器是濕式多片離合器，當液壓使活塞按壓驅動盤和跟隨板時，離合器嚙合；當工作液從活塞缸排出時，回位彈簧后退活塞，分離離合器。換檔制動器通常有兩種形式：一種是濕式多盤制動器，其結構與濕式多盤離合器基本相同，只是制動器是用來連接轉動部件和變速器殼體的。使旋轉零件無法旋轉。換檔制動器的另一種形式是外束帶制動器。
The shift clutch is a wet multi plate clutch. When the hydraulic pressure makes the piston press the drive plate and the follow plate, the clutch engages; When the working fluid is discharged from the piston cylinder, the return spring retreats the piston and disengages the clutch. There are usually two forms of shift brake: one is wet multi disc brake, whose structure is basically the same as that of wet multi disc clutch, but the brake is used to connect rotating parts and transmission housing. Make the rotating part unable to rotate. Another form of shift brake is the outer strap brake.
