The transmission shaft is generally provided with a sliding spline composed of a sliding fork and a spline shaft to realize the change of the transmission length. In order to reduce the axial sliding resistance and wear of sliding spline, sometimes the spline teeth are phosphated or sprayed with nylon layer; Some put rolling elements such as needle roller, roller or ball into the spline groove to replace sliding friction with rolling friction to improve transmission efficiency. But this structure is complicated and the cost is high. Sometimes, for transmission with severe impact load, elastic transmission shaft is also used. The splines on the drive shaft shall be provided with lubrication and dust prevention measures. The clearance between the spline teeth and the keyway shall not be too large, and they shall be assembled according to the corresponding marks, so as not to damage the dynamic balance of the drive shaft assembly.

The length and angle of the transmission shaft and their variation range are determined by the general arrangement design of the vehicle. The design shall ensure that the spline sleeve and the shaft have sufficient matching length when the length of the transmission shaft is at a large value; And does not die when the length is small. The included angle of the transmission shaft directly affects the service life of the universal joint cross shaft and needle roller bearing, the efficiency of the universal transmission and the nonuniformity of the cross shaft rotation.

The transmission shaft is used with various main engine products, and the surrounding working environment is relatively complex, such as temperature, humidity, water, steam, dust, sand, oil, acid, alkali, corrosive medium, brine, radiation, etc. it is one of the important factors that must be considered when selecting the coupling. For the working quality of high temperature, low temperature, oil, acid and alkali medium, the flexible coupling with general rubber as elastic element material should not be selected, and the flexible coupling with metal elastic element should be selected, such as diaphragm coupling and serpentine spring coupling.