Three-oil-cylinder movable arm working device of hydraulic excavator

The utility model provides a three-oil-cylinder movable arm working device of a hydraulic excavator. The three-oil-cylinder movable arm working device comprises a movable arm and a power device, the movable arm is hinged to an upper frame through a movable arm pin shaft, and the power device is connected between the movable arm and the upper frame and enables the movable arm to ascend and descend rotatably. The power device comprises a movable arm oil cylinder, the movable arm oil cylinder is connected with a main valve of the excavator, and the power device further comprises two movable arm energy storage oil cylinders. On the basis of two movable arm oil cylinders of a traditional hydraulic excavator, one movable arm oil cylinder is newly added, the three-oil-cylinder movable arm working device composed of the two movable arm energy storage oil cylinders and the movable arm oil cylinder is formed, the movable arm energy storage oil cylinders on the two sides execute the function of lifting the movable arm w