What is Chassis?

What is An Automobile Chassis?

Chassis is the main support structure of the vehicle which is also known as ‘Frame’. It bears all the stresses on the vehicle in static and dynamic condition. In a vehicle, it is analogous to the skeleton in living organisms. The origin of the word Chassis lies in the French language. Every vehicle whether it is a two-wheeler or a car or a truck has a chassis-frame. However, its form obviously varies with the vehicle type.

Ladder Frame simple diagram
Ladder Frame simple diagram

The Chassis has following functions. It

  1. Supports or bears the load of vehicle body
  2. Provide the space and mounting location for various aggregates of vehicle
  3. Supports the weight of various systems of the vehicle such as engine, transmission etc.
  4. Supports the load of passengers as well as the luggage
  5. Withstands the stresses arising due to bad road conditions
  6. Withstands stresses during braking and acceleration of vehicle

Various types of Frames:

Depending upon the application, some of the main types of frame are as below:

Ladder Frame:

A typical ladder frame in the image below:

Ladder-Chassis (Courtesy: SAE International)

Applications of Ladder frame:

Heavy commercial vehicles such as trucks and buses mainly use the ladder frame structure. Some light commercial vehicles like pickup trucks also use the ladder frame.

Tubular Frame:

A typical tubular frame in the image below:

Tubular chassis (Courtesy: DTM Power)

Applications of Tubular frame:

Some racing vehicles and All-Terrain vehicles use tubular frame design.


A typical monocoque in the image below:

Monocoque chassis
Monocoque frame (Courtesy- Lamborghini)

Applications of Monocoque:

Almost all high-performance cars use the monocoque design.

What is Rolling Chassis?

It is the frame in ‘ready to run’ condition. It means that such a frame has engine, transmission, axles, tyres and all the other systems attached to it that are mandatory to run a vehicle (collectively called ‘Running gear’). Hence, it could be legally driven on road.

Manufacturers generally use this term to refer the trucks or buses which they transport to the vehicle body-builder which is where they build the body on them.

Rolling chassis
A typical Rolling frame (Courtesy: Tata Motors)

 Read on: What is Rolling Stability Control?>>

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