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DO YOU KNOW WHAT IS MAIN PART OF AN AUTOMOBILE ???

Yes, you are right it is CHASSIS ! They are referred to as skeleton of an Automobile.A large number of designs in pressed-steel frame a skeleton on which an engine,axle assemblies,transmission,steering mechanism,brakes and suspension members are mounted.

BASIC FUNCTION OF CHASSIS ARE
1.it absorbs the reaction from the movement of an engine and axle.
2.blances the reaction forces of the wheel in acceleration and braking.
3.Absorb aerodynamics wind forces and road shocks through the suspension.
4.Absorb the major"Energy of Impact"in the event of an accident.



Different Type of Chassis

1.LADDER CHASSIS
This is oldest kind of chassis.in early 60s,nearly all cars in world used it as a standard chassis.Even today most of the SUVs & MUVs used this type .

COSTRUCTION

As name is LADDER : it has two longitudinal rails interconnected by several lateral and cross braces.The longitude members are main stress member.They deals with the load and also the longitudinal forces caused by the acceleration and braking.THe lateral and cross members provide the resistance to the lateral forces and futher increase torisional rigidity.

ADVANTAGES
1.it is easy to construct
2.it is good for SUVs & truck

DISADVANTAGES
1.torsional rigidity is lower especially in case of vertical loads and bumps.

USED BY
Truck making company like TATA,ASHOKA LEYLAND.

2.BACKBONE FRAME CHASSIS

This is also one of the oldest type of chassis.

CONSTRUCTION

1.strong for smaller sports car
2.easy to construct by hands
3.chaep for low volume production
DISADVANTAGES
1.not strong enough for high-end sports car
2.it does not provides protection  against side impact
3.cost ineffective for mass production

USED BY
TVR,Marcos

3.TUBULAR FRAME CHASSIS
As ladder chassis is not strong enough,motor racing enginners developed a three dimensional design-tubular space frame.

CONSTRUCTION
Tubular space frame chassis employ dozens of circular-section tubes,but some may employ square-section tubes for easier connection to the body panels, but remember circular section provides the maximum stength,position in diffrent direction to provide mechanical strength against forces from anywhere.

ADVANTAGES
1.it can counter-blance stress from any direction( compared to ladder and monocoque chassis of same weight)
DISADVANTAGES
1.very complex structure
2.cost and time consuming to built.
3.impossible for robotized production
4.it also covers lot of space

USED BY
Lamborghini Diablo,Jaguar XJ22O,ETC

4.MONOCOQUE CHASSIS
Tday,99% cars produced in this world are made of steel monocoque chassis,due to its low production cost and suitability to robotized production

CONSTRUCTION
It is one-piece structure which defines the overall shape of car.While ladder,tubular space frame and backbone chassis provides only the members and need to build the body around them where-as the monocoque chassis is already incorporated with the body in a single piece.In fact,the "one-piece" chassis is actually made by welding several pieces together.The floor pan,which is the largest piece,and other pieces are press-made by big stamping machines.They are spot welded together by robot arms in a stream production line.

ADVANTAGES
1.cheap for mass production
2.proves good in times of crash in case of protection
3.space efficient

DISADVANTAGES
1.heavy
2.impossible for small-volume production

USED BY
all cars ,all current Porsch,Audi


5.ULSAB MONOCOQUE
(Ultra Light Steel Auto Body)

IN 90s,as tougher saftey regulation ask for more rigid chassis,traditional steel monocoque becomes heavier than ever.As a result,car makers turned to alternative material to replace steel,most notable is aluminum.Basically it has the same structure as a conventional monocoque.The diffrence is the use of "hydroform" parts,sandwich steel and lazer beam welding.

CONSTRUCTION

Hydroform is a new technique for shaping metal to desired shape,alternative to pressing use a heavy-weight machine to press a sheet metal into a die,this inevitably creates inhomogeneous thickness result the edges and the cornner are always thinner than surfaces.To maintain a minimum thickness there for the benefit of stifness,car designer have to chose thicker steel metal than originally needed.HYDROFORM technique is very diffrent.Instead of using sheet metal than originally needed.Hydroform technique is very diffrent instead of using sheet metal,it forms thin steel tubes.The steel tube is placed in die which define diesered shape,and then fluid of very high pressure will be pumped into the tube and then expands the latter to the inner surface of the die.since the pressure of the fluid is uniform,thickness of the steel made is so uniform.As a result,designer can use the minium thickness steel to reduce weight.


ADVANTAGES
1.stronger and lighter
2.more efficent than monocoque

DISADVANTAGES
-

USED BY
opel astra,BMW 3-series