【正文】 initiative to zone, passive gear have been transferred to a circle of the End. Dao Dang, the opposite direction to the output shaft rotation. If one pair of meshing gears when we reverse rotation, with a middle gear, it will bee the same to the rotation. Use of this principle, we should add a gear Daodang the media will be rotational direction reversed, it will have a Daodang axis. Daodang installed in the transmission shaft independent crust, and the intermediate shaft parallel axis gear with the intermediate shaft and output shaft gear meshing gears, will be contrary to the output shaft. Daodang usually used for the synchronization control also joins five stalls, stalls and Daodang 5 position in the same side. As a middle gear, the general transmission Daodang transmission ratio greater than 1 file transmission ratio, by twisting, steep slope with some vehicles encountered on the progress stalls falters with a Daodang boost. Ride from the driver of the considerations, better transmission stall, stall adjacent stall more than the transmission changes the ratio of small, and easy to shift smoothly. However, the short ings of the stalls is more transmission structure is plicated, bulky, light vehicle transmission is generally 45 stalls. At the same time, transmission ratio is not integral, but with all of the decimal point, it is because of the gear teeth meshing is not caused by the whole multiples of two gear teeth can lead to the whole multiples of two meshing gears of uneven wear, making the tooth surface quality have a greater difference. Manual transmission and synchronizer Manual transmission is the most mon transmission, or MT. Its basic structure sum up in one sentence, is a twoaxle shaft, where input shaft, the shaft axis and intermediate shaft, which constitute the main body of the transmission and, of course, a Daodang axis. Manual transmission known as manual gear transmission, which can be in the axial sliding gears, the gears meshing different variable speed reached twisting purpose. Typical manual transmission structure and principles are as follows. Input shaft also said that the first axis, and its frontend spline driven directly with the clutch disc sets with the spline , by the transfer of torque from the engine. The first axis of the intermediate shaft and gears meshing gears often, as long as the shaft axis to a turn, the intermediate shaft and gear also will be rotating. Vice also said intermediate shaft axis, the axiseven more than the size gear. Also known as the second output shaft axis, the axis of various sets of gear stall progress can be manipulated at any time in the role of the device and the corresponding intermediate shaft gear meshing, thus changing its speed and torque. With the end of the output shaft spline associated with the drive shaft through the drive shaft torque transmitted to the drive axle reducer. Thus, progress stalls drive transmission path is: input shaft gear often rodents often rodents intermediate shaft gear corresponding intermediate shaft gear the second axis corresponding gear. Reversing the gear shaft can be manipulated by the device pick in the axis movement, and the intermediate shaft and output shaft gear meshing gears, to the contrary to the direction of rotation output. Most cars have five stalls and a Daodang forward, a certain degree of each stall transmission ratio, the majority of stalls transmission ratio greater than 1, 4 file transmission ratio of 1, known as direct stalls, and transmission ratio is less than 1 No. 5 stall called accelerated stall. Free at the output shaft gear in a position of nonengagement, unacceptable power transmission. The t