Components of an Automobile• The basic structure• The power unit• The transmission system• The auxiliaries• The controls• The superstructure
The Basic Structure (Chassis)• This is the unit on which the other units are mounted.• It consists of:- – Frame – The Suspension system – Axles – Wheels – Tyres
1. Frame• There consists of two distinct forms construction in common use: 1. The conventional pressed steel frame to which all units are mounted 2. The integral or frameless construction, in which the body structure is so designed so as to combine the functions of body and frame.
Frameless - Advantages• Reduced weight and consequent saving in fuel consumption• Lower manufacturing costs• Safety to passengers• Increased stability of the automobile
Disadvantages• Reduction in strength and durability• Economical only if it is adopted in mass production• Increased cost or repairs• Convertible cars are difficult to design in frameless construction
2. Suspension System• The objects of the suspension are: – To prevent the road shocks from being transmitted to the vehicle components – To safeguard the occupants from road shocks – To preserve the stability of the vehicle while in motion
Suspension system• There are two distinct types of suspension systems: – The conventional system, in which the road springs are attached to a rigid beam axle. – The independent system, in which there is no rigid axle beam and each wheel is free to move vertically
3. Axles• It is the wait carrying members, may be on the rear or front, are beams supported at ends.• Axles are subjects to different kin of loads: – Vertical load due to self weight – A fore and aft load due to driving and braking – Torque reactions due to drive and brake – Side thrust due to centrifugal force during conference
Axles• There are three different types live rear axles a) Fully floating type b) Three quarter floating type c) Semi-floating type
4. Wheels• Different types of wheels have been used in automobiles over generations according to the requirement Wire-spoked wheels Pressed steel wheels Light alloy wheels
The Power Plant (Engine)• The engine provides the power to move the vehicle• It generally consists of an IC engine, either SI or CI• Gas turbines also have been used in vehicles• Now, electric batteries for propelling the vehicle
The Transmission System• The transmission system consists of a – Clutch, – Gear box, – Propeller shaft, and – Differential
The Transmission System• The functions of a transmission system are: – To disconnect the engine from road wheel when desired – To connect the engine to the driving wheels without shock – To vary the leverage between the engine and the driving wheels
The Transmission System– To reduce the engine speed permanently in a fixed ratio– To turn the drive through a right angle– To make provision for the flexing of the road springs
The Transmission System• The various components which perform the above mentioned functions are: – Clutch:- To disengage the system from the engine and to engage without shock to road wheels – Gear box:- Provides the necessary leverage variation between the engine and road wheels
The Transmission System– Bevel pinion and crown wheels:- They turn the drive round through 90° and also provide permanent reduction in speed– Universal joints:- Provide for the relative movement between the engine and the driving wheels due to flexing of road springs.– Differential:- Helps to attain different speeds at different wheels while taking a turn
Different types of arrangementsThe different types of the arrangement of transmission could be• Front engine and front wheel drive• Rear engine and rear wheel drive• Front engine and four wheel drive
Front engine FWD• The power is transmitted to front axles, from the front engine (Front Wheel Drive)• A few advantages are: i. The propeller shaft is eliminated. This permits low chassis height ii. The pulls the car than pushing it, avoiding skidding tendency. iii. Better road adhesion.
FWD• A few disadvantages are: i. The whole arrangement over front wheels is complicated. ii. Constant velocity joints have to be used instead of universal joints iii. Decrease of tractive forces when the vehicle is up the grade.
Rear engine RWD• The engine is placed at the rear and the rear wheels are the driven wheels• Advantages are: i. Better tractive forces up the grade ii. Front axle construction is simplified iii. Absence of propeller shaft allows decrease in chassis height
RWD• The disadvantages are: i. May lose balance at high speeds. ii. Complicated linkage is required between the engine, clutch and gearbox. iii. Rear position of engine, cooling effect is reduced.
Front engine four wheel drive• Vehicles which operate on rough roads and unexpected road profiles, all the four wheels are the driving wheels• It has got an extra transfer box, which divides the torque between front and rear wheels.• Also there is a provision for disengaging the front wheels when not required.
4WD• The main advantage of the 4WD is that when any wheels fall into a ditch or a hole, they can be driven out with the help of other wheels or power being delivered to the same wheel• But this advantage can only at the cost of extra fuel consumption.
ClassificationAutomobiles can be classified in different in ways according to:-1.Use i. Mopeds ii. Motor cycles, scooters iii. Cars, jeeps iv. Buses and trucks
Classifications2. Capacity i. Heavy transport ii. Light weight transport2. Make and model i. Honda, Bajaj, TVS, etc. ii. Maruti Suzuki, Tata, Mahindra etc. iii. BMW, Audi, Ford, Mitsubishi etc.
Classifications4. Fuel Used i. Petrol vehicles ii. Diesel vehicles4. Body style i. Closed cars e.g., sedan, coupe etc. ii. Open cars e.g., convertible iii. Special styles e.g., estate cars, station wagons etc.
Classifications6. Transmission i. Manual ii. Semi-automatic iii. Fully-automatic iv. Continuously variable transmission v. Automated manual
Car Body StylesI. Closed cars: a. Sedan – has two or four doors, single compartment with two rows of seats. b. Hatchback – A sedan with a door at the back c. Coupe – only one row of seats for two persons. Only two doors are provided.
Car Body StylesII. Open cars a) Sports – Has two doors or less, provided with a collapsible hood, a fold-flat windscreen and removable side-screen. b) Convertible – Roof in this is of folding type. So the car roof can be closed or opened.
Different Open Cars Chevrolet Camaro Convertible
Car Body StylesIII. Special styles a) Estate car – A sedan with the passenger roof extended up to rear end. Rear seats are usually collapsible for loading. b) Station wagon – Rear doors and four or five person seating capacity.