While turning, the front wheel of the respective side, turns with a greater angle than the wheel of the other side. In order to avoid skids, the front wheels must turn about the same Instantaneous Center “I” which lies on the axis of the back axle.

A fundamental equation of the steering mechanism is derived to find whether the applied mechanism is suitable and effective to use. The fundamental equation is

The equation will not remain same and it will change according to the types of steering mechanisms.

What is Instantaneous Centre?

Instantaneous center is defined as the center where the translation and rotation of all mechanism or links lies. In the above image, we can observe that the instantaneous center lies at the back axle axis.

The condition for correct steering is that “all the four wheels must turn about the same instantaneous center.”

Types of Steering Mechanisms:

There are two different types of steering mechanisms in automobile. They are 

1. Davis Steering Mechanism.
2. Ackermann Steering Mechanism.

Let us read about these two types of steerings in automobile and their equation.

Davis Steering Mechanism:

Davis Steering is one of the mechanisms in steering that consists only sliding pairs, it means the pairs in the mechanism will slide while steering the vehicle. The fundamental equation of this mechanism is satisfied in all the position. In this mechanism the instantaneous point or centre is achieved at centre of the wheel base (l). Therefore, the equation becomes

In Davis Steering, we need to apply more effort to turn the vehicle because the mechanism is a sliding type.

Ackermann Steering Mechanism:

Ackermann Steering is another type of mechanism that have turning pairs and no sliding pairs as like Davis Steering; due to this turning pairs, the Ackermann Steering requires less effort compared to Davis Mechanism.

In this type of mechanism, the fundamental equation can be satisfied only at 3 positions of the Automobile. The three positions are as follows;

• While the vehicle moves along a straight path.
• While the vehicle is steering to the left at a correct angle.
• While the vehicle is steering to the right correct angle.

The mathematical equation of this mechanism is given as  

Advantages of Types of Steering:

Advantages of Davis Steering Mechanism:

The advantages of Davis Steering Mechanism are

• It satisfies the fundamental equation at all the positions and turns instead of sticking to few turns.
• We can say that Davis Steering is an exact mechanism of steering.
• The construction is easy.
• The whole power of driver is converted to the wheels while turning.

Advantages of Ackermann Steering Mechanism:

The advantages of Ackermann Steering are

• Due to its turning pairs, it requires less effort to operate.
• Ackermann acquires less wear and tear problems.

Conclusion:

Mechanisms are the main important things that responsible for most of the movements in machines and automobiles. It plays important role in automobiles also when it comes to steering mainly. All the steering types that are following now-a-days are based upon Davis and Ackermann Steering.

The technology is advanced and even the steering types also. Now-a-days, power steering (we will discuss in upcoming articles) is using in the automobiles and resulting a good efficient and easy steering.