Automobile Engineering

UNIT IIntroduction to Automobile

EngineeringEr.Ravindra Ghodke

Vehicle LayoutVehicle Layout.bmp

jeep-u-joint-diagram.gifVehicle Layout.doc

Chasis with gear box.jpg

• The following main components of the Chassis are

1.Frame: Frame 1.jpg /

Frame less Chasis.jpg / 800px-ToyotaTundraChassis.jpg2. Engine or Power plant: Engine.gif /

Engine showing Clutch.jpg3. Clutch: Clutch Disc.jpg / 800px-Car_clutch.png

4. Gear Box : 6 speed gear box.gif / Gear Box.jpg / 5 speed Gear Box.jpg / Gearbox_diagram.JPG /gearbox_page.jpg

5. U Joint : UJ of truck.jpg /ujoint.gif / ujoint_weldedcap1.gif

6. Propeller Shaft : Propeller.jpg / Propeller shaft.jpg

7. Differential:Diff box.jpg / diff_diagram.jpg / Differntial box.jpg

Vehicle Layout - Engine Location and Drive

Arrangement:• The automobile layout describes where on

the vehicle the engine and drive wheels are found.

• Many different combinations of engine location and driven wheels are found in practice, and the location of each is dependent on the application the vehicle will be used for.

• Layouts are divided into two categories:

1.Front wheel drive, 2. Rear-wheel-drive

1. Front-wheel-drive layouts• Front-wheel-drive layouts are those in which

the front wheels of the vehicle are driven.

• The most popular layout used in cars today is the front-engine, front-wheel drive, with the engine in front of the front axle, driving the front wheels.

• As the steered wheels are also the driven wheels, FF (front-engine, front-wheel-drive layout) cars are generally considered superior to FR (front-engine, rear-wheel-drive layout) cars in conditions such as snow, mud or wet .

Advantages:

• Gives more interior space.

• Greater Fuel Economy.

• Improved Traction and directional stability on snowy, mud ,wet roads etc

• Weight shifting limits the acceleration of a front-wheel-drive vehicle

• Weight: Fewer components usually means lower weight.

• Low cost

• Improved drivetrain efficiency

Disadvantages• Front-engine front-wheel-drive layouts are

"nose heavy" with more weight distribution forward, which makes them prone to understeer, especially in high horsepower applications.

• Torque steer is the tendency for some front-wheel-drive cars to pull to the left or right under hard acceleration.

• Front-wheel-drive cars have the weight of the engine over the driving wheels, hence problem to accelerate up a wet hill

• The FF transverse engine layout restricts the size of the engine that can be placed in modern engine compartments, so it is rarely adopted by powerful luxury and sports cars.

• It makes heavier use of the front tires (i.e. accelerating, braking, and turning), causing more wear in the front than in a rear-wheel-drive layout.

Rear-wheel-drive layouts• Rear-wheel drive (RWD) typically places the

engine in the front of the vehicle and the driven wheels are located at the rear, a configuration known as front-engine, rear-wheel drive layout (FR layout).

• The FR layout is often chosen for its simple design and good handling characteristics

Advantages:

• Even weight distribution.

• Weight transfer during acceleration — During heavy acceleration, weight is placed on the rear, or driving wheels, which improves traction.

• No torque steer.

• Steering radius: smaller steering radius for a given wheelbase.

• Better handling at the hands of an expert — the more even weight distribution and weight transfer improve the handling of the car.

Advantages:• Better braking : the more even weight

distribution helps prevent lockup from the rear wheels becoming unloaded under heavy braking.

• Improved Towing

• Easy Serviceability

• Robustness

Disadvantages• Under heavy acceleration (as in racing),

oversteer and fishtailing may occur as the rear wheels break free and spin.

• On snow, ice and sand, rear-wheel drive loses its traction advantage.

• Decreased interior space.

• Increased weight

• Higher initial purchase price

• The possibility of a slight loss in the mechanical efficiency of the drivetrain

Four-wheel-drive layouts• Most 4WD layouts are front-engine and are

derivatives of earlier front-engine.

Types of Vehicle BodiesThe Automobile bodies are divided in two groups

Passenger Vehicle Commercial or Goods

body body

• According to Chassis design the body can divided into

1. Conventional Type

2. Integral Type

3. Semi- Integral Type

• According to other usage:

1. Light vehicle Bodies - cars, jeeps

2. Heavy vehicle Bodies – Busses, Lorries

3. Medium vehicle Bodies - Vans, Metadoors

The body of the most vehicle should fulfill the following requirements:

1. The body should be light.

2. It should have minimum number of components.

3. Provide sufficient space for passengers & 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 life

10.It should provide good vision and ventilation.

Chassis Types• There are three types of frames:

1. Conventional frame

2. Integral frame

3. Semi-integral frame

Conventional Chassis Frame

Conventional Chassis Frame

Integral Chassis Frame

Integral Chassis Frame

Integral Chassis Frame

Semi Integral Chassis Frame

Semi Integral Chassis Frame

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