The dynamic stress test on some key components used in SS_(7D) electric locomotive,combined with FEA calculating,is optimized to the bogie suspension arm and installing seat to ensure the bogie more reliability and safety.

Combined with the practical construction condition of the curve cast-in-site continuous beam, the article stresses to set forth the control of the sectional construction alignment of the cantilever form traveler and the construction technology of the closure section, and introduces some key problems met in the course of construction and some error-correcting methods.