Described is the structure of the assist steering device applied on bolsterless bogies as well as the operation test results on the special test line of Japan\'s Railway Technical Research Institute.

Discussion on measures to improve the reliability of relaying auxiliary device;

In this paper, such auxiliary devices as gas shielded unit, cooling circuit, welding fixture and auxiliary heating source are introduced in detail, and the emphasis is placed on their function, classification, feature and their research status in order to expand the application of friction stir welding technology.