Automatic triggering device for brake spraying system of truck

The utility model discloses an automatic triggering device for a brake spraying system of a truck. The automatic triggering device comprises a long-barrel-shaped barrel body, an opening triggering shifting piece, a closing triggering shifting piece and a triggering ball, wherein the opening triggering shifting piece and the closing triggering shifting piece are arranged in the barrel body and located at the ends of the two sides of the barrel body, and the triggering ball is arranged in the barrel body, can freely move in the barrel body and is used for triggering. When the barrel body is installed and fixed on the truck, the barrel body and the horizontal direction are arranged at an inclined angle, and one side of the opening trigger shifting piece is higher than one side of the closing trigger shifting piece. By means of the ingenious design, when the truck is in the downhill running process or the braking speed reduction process, the trigger ball moves towards the opening trigger shifting piece, so that t