Abstract：In order to solve the problem with low level of automation in the sprinkler truck equipped with a reel type sprinkler irrigation machine currently, an automatic folding spraying arm driven by an electric cylinder is designed, and an end face seal hinge, which can self-seal when the spray arm is fully extended, is designed in the joint of the arm. Based on the motion characteristics of the spray arm, such as retracting on both sides of the frame when fully folded and hinged and sealed when fully extended, the parametric constraint equation of each member was established, and the size of each member was determined. Kinematics of the spray arm is analyzed by vector equation method. The angle, displacement, velocity and acceleration of the push rod of the electric rod are input variables, and the angular displacement, angular velocity and angular acceleration of each member are output values. The motion simulation block diagram of the spray arm is built and analyzed in Matlab Simulink. The results show that when the nozzle 1 is fully folded, the angle between nozzle 1 and the horizontal direction is 90°. When fully deployed, the three nozzles rotate 90°, and the hinge of each nozzle is completely closed without water leakage. These facts indicate that the design is reasonable in a certain degree.〓
