Automobile chassis is a skeletal frame which serve as the foundation of a vehicle, and the underpart of a motor vehicle, on which mechanical parts like engine, axle assemblies, tires, brakes and etc. are mounted.

Chassis is a French term was initially used to donate the frame or main structure of a vehicle.

The term rolling chassis consists of a frame and the rolling gear like the engine, drive shaft, transmission, differential, suspension etc. The functional components are described as a rolling chassis.

Automobile chassis are usually made of light sheet metals or some composite plastics. The body of a vehicle is design to suit the structure of chassis.

The primary function of chassis is to provide the strength needed for supporting vehicular components, it also help to avoid noise, vibrations and harshness, and helps to keep a vehicle rigid, stiff and balance.

Components of chassis

Automobile Chassis generally consists of the following components which are designed to fit on it. They are:

  • Frame
  • Suspension System
  • Steering mechanism
  • Radiator
  • Engine
  • Transmission system (clutch, gearbox, propeller shaft etc.)
  • Propeller shaft
  • Rear springs
  • Road wheels
  • Differential,half shaft, universal joints
  • Brakes and Braking System
  • Storage battery
  • Silencer
  • Shock absorbers
  • Fuel tank
  • Petrol and hydraulics pipes

Types of Chassis

There are two different types of automobile chassis used in a vehicle. They are:

  • Conventional chassis or frame full chassis
  • Non Conventional chassis or frameless chassis

1. Conventional chassis or frame full chassis:

This type of automobile chassis supports all the systems in a vehicle. Such as, engine, transmission system, steering system, suspension system and etc. The body of the chassis is made as a separate unit which are joined with ladder frame.

The conventional chassis has the ability and capacity to take higher load and strength to resist the complete load of the vehicle, but the body tends to vibrate easily and refinement is lower in the overall vehicles. This type of chassis are used in trucks, bus, bigger vehicles including SUV’s.

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Types of Conventional chassis (Frame full chassis)

There are three major types of chassis used in the conventional type of chassis, they are:

  • Ladder chassis
  • Backbone chassis
  • Monocoque chassis

1. Ladder chassis: This type of conventional chassis is one of the oldest forms of automotive chassis, it is mostly used by bigger vehicles like SUV. It is easier to repair after accidents and crucial for taxicabs, because damaged bolt-on fenders can be replaced. The ladder chassis resembles a shape of a ladder having two longitudinal rails inter linked by several lateral and cross braces.
The grand-Am allows tubular space frame cars to replace their uni body counterparts, as the cars can easily be repaired with new clips.

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Cars with ladder chassis:

  • Opel Olympia
  • Lincoln car
  • Toyota Tundra
  • Ford Panther Series
  • Citroen Traction Avant

2. Backbone chassis: This type of automotive chassis or automobile chassis is strong and powerful enough to provide support smaller sports car. It has a rectangular tube like backbone, usually made up of glass fibre that is used for joining front and rear axle together.
The vulnerable parts of drive shaft are covered by thick tube. The whole system is extremely reliable. However, if a problem occurs, repairs are more complicated.
Backbone chassis is easy to make and cost effective. Standard-conception truck’s superstructure has to withstand the torsion twist, and subsequent wear reduces vehicle’s lifespan and the half-axles have better contact with ground when operated off the road. This has little importance on roads.

Cars with backbone chassis:

  • Skoda 420
  • Tatra 26
  • Lotus Elan
  • Lotus Espirit
  • DeLorean DMC12

3. Monocoque Chassis: This is a one-piece structure that prescribes the overall shape of a vehicle. Since monocoque chassis is cost effective and suitable for robotised production, most of the vehicles today make use of steel plated monocoque chassis. This type of automotive chassis is manufactured by welding floor pan and other pieces together.

Cars with Monocoque chassis:

  • AUDI A4 and A6 series
  • BMW X series
  • Ford cars (most of them )
  • Ex:ford ikon,ford fiesta etc.
  • Fiat Linea,Punto etc.

2. Non conventional or frameless chassis:

in this type of chassis the body itself act as frame and It supports all the
systems in a vehicle such as, Engine, Transmission system, Steering system, Suspension system. The non conventional chassis has no ladder frame. Less rattles and squeaks are developed and handling is better due to the higher body rigidity and weight. But the disadvantage is that, the load carrying capacity is lower and It is not safe in accidental condition. It is mostly used in hatchback and sedan cars.

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Classification of automobile chassis

Classification of chassis is a very broad topic due to the multiple control of chassis, design of the chassis and the numbers of driving wheel chassis. In this article you’ll get to know the basic knowledge on all these classification of an automobile chassis.

Classification of chassis base on the control chassis are classified into three. They are:

  • Conventional Forward Chassis
  • Semi Forward Chassis
  • Full Forward Chassis

1. Conventional Forward chassis: as already explained previously, conventional chassis are use in bigger vehicle. The chassis portion can not be utilized for carrying passengers and goods and engines are fitted at the front of the driver cabin or driver seat of the vehicles.

2. Semi Forward Chassis: in this chassis half portion of the engine is in the driver cabin and remaining half of the engine is outside cabin such as in tata trucks. The arrangement of the chassis is utilized for carrying extra passengers.

3. Full Forward Chassis: in this type of chassis the complete engine is mounted inside the driver cabin, and the seat is fitted above the front wheel.

Classification of chassis base on the engine positioned to the chassis are classified into four. They are:

  • Engine at front
  • Engine fitted in front but crosswise
  • Engine fitted at the center of the chassis
  • Engine fitted at the back

1. Engine at the front: in this design there’s enough space available for luggage behind the rear seat and the weight of vehicles is well balance, and Increased efficiency of cooling system. Conventionally the engines are fitted at front & drive is given to the wheels from the “rear”.

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2. Engine fitted at the front but crosswise: The engine is fitted at the front and drive is given to front wheel. In this chassis design vehicle has more road holding capacity and clutch, gearbox and differential are usually made as one unit, so cost is reduced, but low floor is available in the vehicle.

3. Engine fitted at the back: This is a rear engine drive and the vehicles employing system is dolphin, and has better adhesion on road specially when climbing hills. In this chassis design flat floor is available since the long propeller shaft is eliminated and give stable driving since the centre of gravity is lowered.

4. Engine fitted at the centre of the chassis: in this chassis design the drive is given from the rear. The arrangement provide full space of floor for use.

Classification of chassis base on the number of wheels fitted in the vehicles and the number of driving wheels chassis are classified into the following types:

  • 4×2 drive chassis vehicle.
  • 4×4 drive chassis vehicle.
  • 6×2 drive chassis vehicle.
  • 6×4 drive chassis vehicle.

1. 4×2 Drive chassis vehicle: Describes to a vehicle that has two-wheel drive (2WD) with four wheels. “4×2” in a 2WD vehicle means there are 4 wheels total and 2 wheels that are driven. The driven wheels can be either back or front wheels but are usually the back wheels.

2. 4×4 Drive chassis vehicle: Is a vehicle that has four-wheel drive (4WD). “4×4” in a 4WD vehicle means there are 4 wheels total and 4 wheels that are driven.

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3. 6×2 Drive chassis vehicle: The 6 X 2 tractors configurations also have three axles; however, one of the two rear axles is a non-driving or “dead” axle. The non-driving axle has no internal gearing to provide drive to the wheels of the axle. As a result, there is no internal friction or losses due to lubricant churning, which reduces parasitic losses in the drivetrain.

4. 6×4 Drive chassis vehicle: A typical three axle Class 8 tractor today is equipped with two rear drive axles and is commonly referred to as a 6 X 4 configuration meaning that it has four-wheel drive capability. 6×4 units are more common in long distance haulage in larger countries.