The action of arm triangle Bai is the balance supporting action.

When the car is driving on the uneven road surface, the tire will swing up and down, that is to say, it is completed by the Dao swing of the triangle arm. The tire is installed on the axle head, and the axle head is connected with the triangle arm through the ball head. The triangle arm is actually a universal joint. When the relative positions of the driving side and the driven side change, they can still act in association. For example, the vibration absorber is compressed to make the A-shaped arm swing upward when turning.

The triangle arm is connected with the subframe through the hinged sleeve at the front connection point of the subframe, and the force and impact of the wheel are transmitted to the body through the hinged sleeve at the front connection point of the subframe. The hinged sleeve at the front connection point of the subframe is the place where cracking may occur, which is the place where the hinged sleeve at the front connection point of the subframe is likely to occur in case of "shaft breaking" accident Set.