What is Chassis Frame in Cars and What are Its Functions?

The chassis frame in vehicles is the most important support component in a vehicle, supporting it from underneath.

The primary purpose of this component is to bear the entire weight of the vehicle, thus, keeping the car intact while it experiences driving forces, such as braking, turning or acceleration.

If you want to know in detail what a chassis frame is, what a frame is in general, and its types and functions, read on.

The structure on which the parts of your vehicle are mounted is called the chassis, commonly referred to as the frame or backbone.

As mentioned above, it is the basis for the bodywork, drivetrain, suspension, and engine. The chassis frame also supports the vehicle and withstands numerous stresses that may arise during operation while also giving the vehicle strength, rigidity, and structural integrity.

Depending on vehicle applications, there are different types of chassis frames:

1. Ladder Frame

The oldest and the most basic one, a ladder frame, is made of two longitudinal rails that different cross members further connect. These frames can be commonly found in vehicles that require extreme rigidity and strength, such as trucks and SUVs.

2. Monocoque or Unibody Frame

Unlike the previously mentioned ladder frame, a Monocoque frame combines the frame and body into a single unit. In this system, the structural integrity comes from the body panel, removing any need for a separate frame. These frames, which are commonly found in passenger cars, offer improved fuel efficiency, enhanced handling and reduced vehicle weight.

3. Space Frame

Comprising a lattice-like structure, space frames are made of interconnected tubes, making them lightweight. Given its construction, this type of chassis frame is generally used in high-performance sports cars or supercars. They can withstand high forces while maintaining driving comfort and handling.

4. Backbone Frame

As the name suggests, this frame comprises a  rectangular hollow cross-section and a tube that directly passes through for connection between the front and rear suspension. This creates a human-like skeleton structure. This chassis frame helps provide better support between the axle and the ground. Further, a vehicle with this frame enjoys extended stability.

When talking about the chassis frame, both terms can seem interconnected. However, they are not. The frame is a broader component, which is the foundation of a vehicle on which the chassis is built.

Thus, the frame supports the chassis the same way the chassis supports the vehicle. All components of the chassis are fitted into the vehicle frame.

Forming the structural support of a vehicle, the frame has the following functions:

• Support the chassis and its components.
• Ensure proper positioning of the entire components of the chassis.
• Counter dynamic and static load on the vehicle.

Typically, there are three basic types of frames used in vehicles. They are:

1. Conventional Frames

This type of frame is connected to the chassis using springs. It is also called non-load carrying frames, as the function is entirely transferred to the vehicle suspension system.

2. Integral Frames

An integral frame means the body of the chassis itself functions as the frame. These are also called mono units or chassis less.

3. Semi-integral Frames

Somewhat similar to integral frames, this is made of a frame, and the other half is a frameless unit. The frame unit supports the engine and gearbox.

While driving, there are certain forces that the chassis frame has to endure to achieve optimal vehicle handling and comfort. These forces include:

1. Vertical Bending

The force on a vehicle due to vertical weight is termed as vertical bending. The weight of the passengers sitting in a car or the car’s weight is an example of vertical bending.

2. Longitudinal Torsion

This happens when one vehicle wheel is lifted while the other stays on the ground. This, in turn, twists the frame, leading to longitudinal torsion.

3. Fore and Aft Loading

When you apply sudden brakes or acceleration, some amount of force is endured by the chassis frame. When braking, the force goes towards the frame’s front, while acceleration releases force towards the rear frame.

4. Impact Roads

When driving on uneven roads, the vehicle’s chassis frame may collapse or lose its shape. These types of sudden forces are called impact roads.

5. Overloading

Overloading is another type of force acting upon the vehicle’s chassis frame, which indicates that the vehicle has become overweight, putting too much pressure on the frame.

Now that you know more about chassis frames and the meaning and function of frames in a broader aspect, check out these aspects during your next big purchase! You should also be aware of the different types of forces that act on the chassis frame as these have a lot to do with the overall driving efficiency and handling comfort.