液力变矩器可以传递和增加发动机扭矩，但转矩比不大，速度范围不宽，远远不能满足车辆运行工况的需要。变速箱维修价格是车辆上非常重要的部件，它可以改变传动比，扩大驱动轮转矩和转速的作用。
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.
随着现代科技的发展，变速箱也有了升级，从手动变速箱，到现在无级变速箱，从无同步器到有同步器，操控越来越方便。为了进一步提高扭矩，扩大其变速范围，提高车辆的适应性，在液力变矩器后面安装了辅助传动装置，并经常采用行星齿轮机构。
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.
行星齿轮传动由行星齿轮机构和离合器、制动器、单向离合器等执行机构组成。行星齿轮机构通常由多排行星组成。行星的数量取决于文件的数量。
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.
行星齿轮传动的换档执行器包括换档离合器、换档制动器和单向离合器。
The shift actuator of planetary gear transmission includes shift clutch, shift brake and one-way clutch.
换档离合器是湿式多片离合器，当液压使活塞按压驱动盘和跟随板时，离合器啮合；当工作液从活塞缸排出时，回位弹簧后退活塞，分离离合器。换档制动器通常有两种形式：一种是湿式多盘制动器，其结构与湿式多盘离合器基本相同，只是制动器是用来连接转动部件和变速器壳体的。使旋转零件无法旋转。换档制动器的另一种形式是外束带制动器。
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.
