The utility model discloses a loader working valve accessory allies oneself with changeable hydraulic system of maximum output flow, a serial communication port, including the working barrel of bringing hydraulic fluid port, oil -out no. 1, oil -out no. 2 into, the oil -out no. 1 of working barrel passes through rubber tube assembly and articulate with the main oil inlet of working valve, and the oil -out no. 2 of working barrel passes through rubber tube assembly and articulate with the oil inlet mouth of large -traffic diverter valve, and the AUX hydraulic fluid port of working valve passes through rubber tube assembly and articulate with the AUX hydraulic fluid port of large -traffic diverter valve, and the oil return opening and the oil return integrated package of large -traffic diverter valve pass through rubber tube assembly and articulate. The utility model discloses using and singly advancing pair working barrel of the series connection that goes out, the output hydraulic flow of working barrel is unchangeable, through the work of external large -traffic diverter valve and working valve, makes working barrel accessory under the same circumstances of engine speed ally oneself with the maximum output power who has two kinds of differences.