CHASSIS

CLASSIFICATION OF AUTOMOBILE1. Capacity (HMV ,LMV)2. Power ( Petrol, Diesel, Gas, Electric)3. Use (Cars ,Buses ,Trucks ,Motor Cycles )4. Wheels (2.3.4.6 ….)5. Make ( Bajaj, Vespa, Hero, Honda, Maruti)6. Drive (LHD, RHD)7. Transmission ( Conventional, Automatic)8. Purpose (Passenger,Goods)

CHASSIS Chasis is a French term which denotes the

whole vehicle except body in case of heavy vehicles.

Chassis consists of engine, brakes, steering system & wheel mounted on the frame, differential, suspension.

Propel and control a automobile

COMPONENTS OF CHASSIS Engine Transmission (Clutch, Gear Box, Propeller

shaft, Differential) Controls (Braking and Steering) Basic Structure (frame, Suspensions, Axles,

wheels, tyres) Electrical systems

REMAINING Auxiliaries Superstructure

FUNCTION OF VEHICLE SYSTEMSVehicle System Function

Body • Provide durable attachment for other major systems• Provide safe and pleasant seating environment for all passengers• Protect passengers from crashes

Chassis • Provide capability to steer the vehicle• Provide capability to brake the vehicle safely• Provide isolation between road and passengers

Powertrain • Provide capability to accelerate the vehicle by transferring torque to wheels• Provide capability to control vehicle speed• Meet regulatory exhaust requirement

Climate Control • Maintain comfortable temperature distribution for passengers• Provide windshield defrost capability

Electrical & Electronics • Provide power supply where needed• Provide desirable entertainment system• Provide functional censors and controls

GENERAL CONSIDERATION RELATING TO CHASSISBody of most vehicle should fulfil the following

requirements:

1. The body should be light.2. It should have minimum number of components.3. It should provide sufficient space for passengers and

luggage.4. It should withstand vibrations while in motion.5. It should offer minimum resistance to air.6. It should be cheap and easy in manufacturing.7. It should be attractive in shape and colour.8. It should have uniformly distributed load.9. It should have long fatigue life10.It should provide good vision and ventilation.

Classification Chassis acc to layout

Conventional Semi-forward Full-forward

CHASSIS CLASSIFICATION BASED ON ENGINE LOCATION Engine fitted at front Engine fitted at Back Engine fitted at centre Engine fitted at front but crosswiseCHASSIS CLASSIFICATION BASED ON Number of Wheels fitted in the vehicles and the number of driving wheels

•4x2 drive chassis vehicle.•4x4 drive chassis vehicle.•6x2 drive chassis vehicle.•6x4 drive chassis vehicle.

FITTED AT FRONT & DRIVE IS GIVEN TO THEWHEELS FROM THE “REAR”1. Enough space is available for luggage

behind the rear seat2. The weight of vehicles is well balance3. Increased efficiency of cooling system

Engine is fitted at front & drive is given to front wheel1. Low floor is available.2. Vehicle has more road holding capacity.3. clutch , gear box & differential are usually

made as one unit, thereby cost is reduced.

ENGINE IS FITTED IN FRONT BUT CROSSWISE: BMC Maruti

ENGINE FITTED AT THE CENTRE OF THE CHASSIS: Drive is given to the rear As in royal tiger world master buses This arrangement provide full space of floor

for use

ENGINE FITTED AT BACK1. Flat floor is available since long propeller shafts

are eliminated2. With elimination of propeller shaft the centre of

gravity lowered giving stable driving3. Better adhesion on road specially when climbing

hill.4. While Climbing hills proper adhesion may be

affected since the weight of vehicles moves to the rear , thereby reducing the weight on the front wheel.

5. As a result of grouping of the engine with clutch, gear box and differential, the repair and adjustment become difficult due to congestion at the rear.

FRAMES

TYPES OF CHASSIS FRAMES:THERE ARE THREE TYPES OF FRAMES1. CONVENTIONAL FRAME2. INTEGRAL FRAME3. SEMI-INTEGRAL FRAME

CONVENTIONAL FRAMEa.Channel Section - Good resistance to

bending

b. Tabular Section - Good resistance to Torsion

c. Box Section - Good resistance to both bending and Torsion

INTEGRAL FRAME (FRAMELESS) used now a days in most of the cars no frame and all the assembly units are

attached to the body Due to elimination of long frame it is cheaper Only disadvantage is repairing is difficult.

SEMI - INTEGRAL FRAME half frame is fixed in the front end on which

engine gear box and front suspension is mounted.

It has the advantage when the vehicle is met with accident the front frame can be taken easily to replace the damaged chassis frame.

This type of frame is used in FIAT cars and some of the European and American cars.

SOME OF IMPORTANT CHASSIS FRAMES ARE: Ladder Frame Tabular Space Frame Monocoque Frame Aluminum Space Frame Carbon Fibre frame

LADDER FRAME: The ladder frame is the simplest and oldest

of all designs. This design offers good beam resistance

because of its continuous rails from front to rear

poor resistance to torsion

A type frameX type frameHigh torsional rigidity

SPRINGING SPACE

TUBULAR SPACE FRAME: It is 3-dimensional design Tubular space frame chassis employs dozens of circular,

rectangular etc section tube, positions in different directions to provide mechanical strength against force from anywhere.

These tubes are welded & forms a very complex structure.

TUBULARADVANTAGES Very strong in any direction (compared with

ladder chassis and Monocoque chassis)

DISADVANTAGES Very complex , costly and time consuming to

be built.

MONOCOQUE Monocoque is a one-piece structure which defines

overall shape of the car. while ladder , tabular & backbone provide only stress members

Today 99% car produced in this planet are made of Monocoque chassis.

Chassis are made by welding of several pieces.(Spot winding).

MONOCOQUEDISADVANTAGES1. It has very complex design .2. Impossible for small volume production.

ADVANTAGES3. Space-efficiency (the whole structure is

actually an outer shell.)4. Monocoque chassis benefit crash

(reproduction) production because it uses a lot of metal.

5. Cheap for mass production.

ALUMINIUM MONOCOQUE- Audi A8 is the first mass production car

featuring Aluminium Space Frame chassis.

To replace conventional steel monocoque mainly for the benefit of lightness.

Audi claimed A8's ASF is 40% lighter yet 40% stiffer than contemporary steel monocoque.

CARBON-FIBER MONOCOQUE

Carbon Fiber is the most sophisticated material using in aircrafts, spaceships and racing cars because of its superior rigidity-to-weight ratio.

Road cars featuring Carbon-Fiber body panels, such as Ferrari 288GTO and Porsche 959.There are several Carbon-fibers commonly used in motor industry.

Kevlar, which was developed by Du Pont, offers the highest rigidity-to-weight ratio among them. Because of this, army's helmets are made of Kevlar. Kevlar can also be found in the body panels of many exotic cars, although most of them simultaneously use other kinds of carbon-fiber in even larger amount.

CARBON FIBRE MONOCOQUEProduction process Carbon-fiber panels are made by growing

carbon-fiber sheets (something look like textile) in either side of an aluminium foil.

The foil, which defines the shape of the panel, is sticked with several layers of carbon fiber sheets impregnated with resin, then cooked in a big oven for 3 hours at 120°C and 90 psi pressure.

After that, the carbon fiber layers will be melted and form a uni-formal, rigid body panel

CARBON FIBRE PANELS Where is the carbon-fiber used ? Body panels or Chassis ? Since body panels do nothing to provide mechanical

strength, the use of carbon fiber over aluminium can barely save weight.

The stress member remains to be the chassis, which is usually in heavier and weaker steel tubular frame.

COMPARISON LADDER AND MONOCOQUE

 Performance -  The monocoque is a lighter design which is a plus for fuel efficiency, It has more torsional stiffness and is by far the better chassis for

performance oriented vehicles. The heavy nature of the ladder chassis makes it tough and it is much

better than the monocoque for carrying heavy loads and towing heavier objects.  

Design -  A unibody bodyshell is difficult to design, build and modify (

platform sharing) when compared to the body on frame but computer aided design (CAD) makes unibody platform sharing much easier.

For body on frame vehicles its easy to build another body even from another bodystyle and place it on a ladder chassis as long as they are of similar dimensions.

Materials -  Unitary bodyshells can be made from a variety of materials steel and

steel alloys, aluminium and aluminium alloys and even carbon fiber or combinations of these materials whereas ladder chassis are usually built from steel.

 

A QUICK COMPARISON

Monocoques

Typical Ladder Frame

VARIOUS LOADS ACTING ON THE FRAME:

1. Short duration Load - While crossing a broken patch.

2. Momentary duration Load - While taking a curve.

3. Impact Loads - Due to the collision of the vehicle.

4. Inertia Load - While applying brakes.5. Static Loads - Loads due to chassis parts.6. Over Loads - Beyond Design capacity.

MATERIALS- WHY IMPORTANT As fuel economy restrictions become tighter,

manufacturers must find new ways to meet them.

This has led them away from using so much steel in the vehicles, and more and more are moving towards aluminum.

A BASIC COMPARISONTwo common alloys used in car manufacturing:

For Aluminum:For Steel:

Density of Steel: 7.88 g/cm3Density of Aluminum: 2.7 g/cm3

Aluminum is about 3 times lighter than steel per unit volume, but can be made just as strong using certain alloys/shapes/bonding methods.

Because of this, AL parts can be thicker, and thus stronger, than their steel counterparts, all while weighing less.

Steel AlYield

Strength(MPa)

294.8 395UTS (MPa) 394.7 420Hardness (HB500) 104 58

THE COST ISSUEWhile Al may seem like a miracle metal for car production, there is a reason not all cars are made from Al... It costs a lot more than Steel.

THE MOVE TO ALUMINUM The first production vehicle to move to an Al

frame was the Audi A8 in 1994. This allowed Audi to make their full-size car

lighter than the competitions (BMW, Mercedes, Lexus...), thus giving them the edge in performance & handling.

This comes at a price premium though, for instance compared to a Lexus LS460 (Steel framed) which costs around $65,000. The A8 starts at $75,000

Audi A8

Lexus LS460

CARS UTILIZING AL FRAMES

Audi A8Jaguar XJCorvette Z06 (GM)

Honda NSXAudi A2Audi R8

SOME OTHER ADVANTAGES... There are some manufacturing

methods that can only be done with aluminum, such as extrusions.

These extrusions allows the Al Space Frame to have about half the amount of parts as a traditional steel monocoque.

Because of all this, Al is already a cheaper material to use for low volume production cars (under 100,000 units a year or so).

IN THE FUTURE While Aluminum may be the wave of the future

for now, some exotic car companies are already looking ahead to composite materials.

Take for example Porsche Carrera GT, which used a completely Carbon-Fiber monocoque construction in addition to Carbon-Fiber body panels.

VEHICLE ATTRIBUTESVehicle Attributes Description

Cost Lowest production, assembly and distribution cost compared to competitive vehicles

Weight Lowest curb weight compared to competitive vehicles in its weight class

Package Best use of the space to provide comfort and amenities to passengers

Safety 5* crash rating from the Federal Motor Vehicle Safety Standard (FMVSS)

Dynamics Best ride & handling performance compared to competitive vehicles

Durability Highest reliability and high mileage durability compared to competitive vehicles

NVH Lowest noise, vibration and harshness compared to competitive vehicles

TYPES OF CARS ON AS PER THEIR DESIGN1) Sports Cars Sports cars are the perfect example of best automobile engineering, sports cars are two-seat small cars that are designed for quick

response to move fast for spirited performance and nimble handling. Nissan GT-R Now a days sports cars have become a first choice for every body,

therefore automobile manufacture are making them more fast and more luxury.

Some example of sports car masterpieces are  Nissan GTR, Lamborghini Veneno, Maserati Alfieri etc.

2) Muscle Cars A type of car designed for powerful and high performance

automobile lovers, These cars have powerful engine, mostly V-8 and above with 2-door.

Apart form this their performance and  their look is muscular and aggressive.

Some common example are  Ford Mustang, Chevrolet Camaro etc.

3) Sedan type Cars It is the car type that we found around us every time any where, well

sedan is a passenger car that has two rows of seats and adequate passenger space in the rear compartment for adult passengers.

In sedan, a four or more people can travel and has a fixed roof that is full-height up to the rear window with two pillar to join roof and window.

The word sedan is taken from Italian sedia “chair” in that closed chair one person can sit.

Some common examples are Porsche Panamera, Audi A8 etc.

4) SUVs type Cars A sport utility vehicle (SUV) is a estate car mostly

available in four wheel drive to drive on-road or off-road having large passenger carrying space.

If you wish to further categorize the SUV car they are sub divided in many type as par their size like Compact SUV, Mid-size SUV, Full size SUV etc.

Some popular SUV’s are BMW X4, Porsche Macan, Maserati Levante etc.

5) Multi-utility vehicles: MUVs Usually based on either a mid-sized car or mini-van

platform. Usually two-wheel drive "people movers". They

have higher ceilings, more storage than a sedan, some of the utility of a SUV with a similar ride,

though from a construction standpoint not as robust.

Great for larger families of 4-5 and comfortable.

In India a good example is the Honda Mobilio

6) HATCH BACKS Passenger cabin with integrated cargo space.