How Does a Control Rod Work?


As we all know, the control rod is an indispensable part of an automobile chassis. But the specific working principle, classification, the role it plays, the selection standard of it is not so clear to anyone, as can be seen on This article will walk us through them one by one.

Working Principle of Control Rods

When a vehicle is turning, due to the centrifugal force, its body will tilt in the opposite direction, which differentiates pressure under wheels on both sides. The outer side is subjected to the greater downward pressure, and the inner side is raised to a certain extent, which could sometimes cause a rollover.

The aim of the adjustable control rod ( which are found in the automobile chassis is to lift the wheels of the vehicle that are held down. Once the wheels are lifted up, they are then pressured down with the aim of forming a balance. This means that the control rod is able to both raise the tires of the vehicle, and apply a pressure downwards.

Classification of Control Rods

According to its purpose and function, it can be divided into the following categories:

1. Front-wheel lower control rod (an essential part of the original vehicle)

—— In the front axle and the front wheel as a separate connection, the lower control rod is responsible for controlling the front wheel inside and outside inclination angle.

2. Balanced control rod for the directional front bundle (an essential part of the original vehicle)

—— On the front wheel lower swing arm on both sides. It is used to control the direction of the front wheel unitedly. At the same time, it can take charge of the forward inclination angle of the front wheel and maintain the tracking ability of the steering wheel.

3. Balanced control rod at the top of front wheel shock absorber tower (commonly known as a top bar, optional part)

—— On the top of the front shock absorber tower, the control rod is used to strengthen the rigidity of engine room and front body, offset the deformation of frame caused by centrifugal lateral torsion (severe deformation can cause tearing of tower top), improve the bending ability of vehicles, increase the bending speed, and reduce the roll angle caused by centrifugal force.

4. The balanced control rod of the front bottom cross beam (commonly known as a front bottom bar, optional parts)

—— In front of the front axle and chassis. It is used to enhance the connection strength between front and bottom crossbeam (front axle) and chassis, reduce the displacement and deformation of front axle caused by centrifugal force and body distortion, and one of its primary functions is also to improve the over-bending performance.

5. Balanced control rod at the top of rear wheel shock absorber tower (commonly known as a rear top bar, optional part)

——On the top of the rear shock absorber tower. It is used to enhance the strength of the tailbox, reduce the transverse distortion caused by centrifugal force at the rear of the carriage, reduce the roll of the tailbox when crossing bending, and improve the vehicle’s crossing performance.

6. Rear-axle suspension reinforcement balance control rod (commonly known as a rear bottom bar, optional part)

—— In the connecting position between the rear axle and the rear chassis of the frame.It is used to strengthen the connection strength between the rear axle and the frame.

7. Frame (Body) Chassis Enhanced Balance control rod (Component)

——In the middle part of the frame chassis. It is used to strengthen the overall rigidity of the frame chassis. Depending on the design of the vehicle, frame structures are different, some of which are omitted or replaced by other structures.


Function of Control Rods

1.Strengthen the rigidity of the car body, prevent the deformation of the car body and four-wheel displacement;

2. Balance four-wheel torsion and increase chassis lifespan;

3. Reduce the two-wheel bumping force and prolong the lifespan of the shock absorber;

4. Prevent positioning displacement and protect parts effectively;

5. Make driving operation more flexible and comfortable;

6. Guarantee turning smoothly and driving safely.

Selection of Control Rods

The hardness of the control rod is determined by the material, body, diameter, arm length, and angle of the rod body. The longer the length of the rod body, the lower the hardness. On the contrary, the longer the length of the arm, the harder it will be. Limited by vehicle width, the length of the pole body can not be determined subjectively, but pole diameter and arm length are relatively easy to adjust. Generally speaking, the material of the control rod is often the same, so changing the hardness of the control rod in automobile refitting is achieved by changing the diameter of the rod or arm. In addition, according to the lever principle, the moment of the arm can be changed by changing the connection point between the cantilever arm and the balancing rod arm. The adjustable balancing rod starts from here as well.

As a professional vehicle suspension part suppliers, AA-TOP is a powerful manufacturer to produce various and high-end control rods.

Have you made up your mind to improve your essential control rod for your vehicle? If yes, AA-TOP will be the right choice you won’t want to miss.

For more information, check out

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