Due to the requirements of structure and economy, the planetary carrier must be designed with the structure of thin left spoke plate, thick right spoke plate, split assembly or integral, so that the pin will inevitably creep in the work. Therefore, it seems that it is not enough to keep the position of the pin shaft relative to the planet carrier by interference only. After a long time of reciprocating motion, the pin will slowly emerge to the left, and the speed will be faster and faster, because as long as there is creep, the original interference will be gradually destroyed. In order to solve the above failure problems, it is necessary to add additional axial positioning to the pin shaft. Generally, there are the following common methods:
(1) In material selection, the whole ductile iron casting is preferred. The split structure can only be used in some unavoidable cases, such as when the connection strength of the right side of the planetary carrier and the next stage parts is very high, and the casting can not meet the requirements. The overall casting structure may cost more than the mold cost, but most of them have a certain number. As long as the modular design is done well, it is easy to form a cost advantage.
(2) In structure, axial positioning must be added to the pin shaft. The common methods are as follows: drilling side pin holes on the left and right web plates, driving them to the depth of the pin shaft, installing the locating pin to fix the pin shaft axially; drilling both sides or only one side; leaving space at both ends of the pin shaft holes on the left and right web plates of the planet carrier to install the elastic ring for the hole; or positioning one end of the pin shaft through the shoulder, and positioning the other end with the elastic ring for the hole. The axial creep of pin shaft is a slow process, and the force is not necessarily large, so both the locating pin and the elastic ring can play the role of axial positioning. In the improved design of planet carrier, the new positioning structure has been used so far, and no similar failure problem has been found, which shows that the design improvement is completely effective and sufficient.