Abstract: The flexible multi-body dynamic theory is applied into the dynamic characters analysis of 4-arms concrete pump truck arms. The arms are thought as flexible ones for simulation, based on which the flexible multi-body dynamic equation for arm system is built by Lagrange equation and virtual work theory. The equation is deduced and numerically solved to analyze the movement situation of each arm. With a dynamic simulation software, a rigid model and a flexible model are both built for the arms. These two models are simulated with the same driving moment, and the deformation curves of each model and the angular velocity curve of the 4th arm are analyzed and compared. The result shows that it is necessary to consider the flexible deformation when studying the arm system of the light and long arm concrete pump truck. At the same time, the mathematic model can support the study for automatic casting.

Key words: Arm, Concrete pump truck, Elastic distortion, Flexible multi-body dynamics