AUTOMOTIVE ENGINEERING

1. AUTOMOTIVE ENGINEERING UNIT 1 CHASSIS & BODY

2. UNIT 1-TOPICS Classification of vehicle, layout with reference to power plant, steering location and drive, chassis, construction and details (frames, sub-frames, defects in frame, frameless vehicles, vehicle dimensions), details of chassis & body materials, Integrated body construction, BIW type and corresponding design parameters, Vehicle interior system (dash board & seating system), Console design, Pillar trims (Type A, B, C), head roofs.

3. CLASSIFICATION OF VEHICLES • There are three main general classifications of the various types of vehicles. They are: • Single unit vehicles or load carriers. • Articulated vehicles • Heavy tractor vehicles.

4. PASSENGER VEHICLES

5. PASSENGER VEHICLES

6. GOODS VEHICLES

7. GOODS VEHICLES

8. Single unit vehicles or load carriers: • Vehicles are conventional 4 wheel type with two axle design in which the front axle is a steering non – driving axle and rear axle is the driving axle. • Articulated Vehicles: • 3 wheeler vehicle with single steering wheel in front and a conventional rear – driving axle. • It can turned about its own tail due to the three wheel construction and has a greater handling ability in unusual places. • The coupling mechanism between semi – trailer and tractor in most of these vehicles is designed for automatic connection and coupling up. • A lever is provided within the drivers approach for coupling operation. • A pair of retractable wheels in front can be raised or lowered automatically along with the coupling and uncoupling operation. • Heavy tractor vehicles: • To move heavy loads tractor or independent tractor vehicles are used. • They commonly operate in pair either in tendon or as puller or pusher. • Figures like 4x2, 4x4, 6x4 etc are commonly used in the classification of vehicles, where the first figure represents the total number of wheels and the second figure the number of driving wheels.

9. CLASSIFICATION BY BODY STYLES Broad classification of cars present in the Indian market: ESTATE/STATION WAGON SPORTS UTILITY VEHICLE MULTI-PURPOSE VEHICLE MULTI-UTILITY VEHICLE SEDAN/NOTCHBACK HATCHBACK PICK-UP TRUCK VAN

10. MOTOR CAR • Carries passengers in the sitting position and also accommodates their luggage. • Light motor vehicles designed to carry passengers and sometimes goods, are broadly classified as follows: • Saloon/Sedan car . E.g:Indigo Manza, Swift Dzire, Logan • Saloon cars have an enclosed compartment to accommodate a row of front and row of rear seats without any partition between the driver and rear passenger seats. • A separate luggage space is made either at the front or the rear based on the location of the engine. • One or two doors are provided on each side of the car but if the car is a hatchback a door replaces the luggage space. E.g. Nano, Indica, Jazz, Punto

11. Coupe • The coupe is the outcome of changes in saloon car design and has two doors, two front seats and a hard roof. • When two additional small seats are provided at the rear, the layout is known as 2+2. • Convertible • Normally cars of this type have two doors and two seats but sometimes two extra seats are also provided. • Generally these have a soft folding roof and wind-up windows to make the compartment either open or closed. • Estate car/station wagon • In this type the passenger roof of saloon is completely extended to the back end so that rear space is increased. • For access a rear door is provided and sometimes the rear seats are designed to collapse to provide additional space for carrying goods. • E.g. Indigo Marina, Octavia.

12. Pick – up • This type of vehicle is generally classified as a two – door front – seating van with an open back to carry mixed collection of goods. E.g. Xenon, Scorpio Getaway • VANS • These are light goods vehicles used for long distances or door – door delivery. • They have seats in the front for the driver and for only one or two passengers. • The engine is usually located over or just in front of the front axle. E.g. Winger, Ace Magic, Omni.

13. COACHES • Coaches carry passengers travelling on long distance and hence the interior is designed to provide the best possible comfort and to minimize fatigue. • For better visibility for passengers large panelled windows are provided on either side extending the full length of the vehicle and across the back seats. • Most coaches have two axle arrangement but sometimes an extra axle is used at the rear for more comfort. • Engines may be mounted longitudinally in the front (position 1) or in the mid – position horizontally (position 2) or at the rear transversely (position 3). • The location of the engine and transmission depends much on the length of the coach, the number of passenger seats, the luggage space and high or low floorboard and seat mounting requirements.

14. LORRIES/TRUCKS • Commercial vehicles used for the transportation of heavy goods are generally referred to as lorries. • Vehicles are grouped into two categories • Rigid truck • Articulated vehicles • Rigid trucks are further classified based on the number of wheel hubs and the number of drive axle hubs • A four wheeler (4 x 2) truck with two driving wheels • A six wheeler (6 x 2) truck with two driving wheels • A six wheeler (6 x 4) truck with four driving wheels • An eight wheeler (8 x 4) truck with four driving wheels.

15. ARTICULATED TRACTOR & SEMI TRAILER • Articulated vehicles use a tractor unit for providing the propulsive power and a semi-trailer for carrying the payload. • The tractor uses a short rigid chassis and two or three axles. • The front axle carries the steered road wheels and the rear axle is the driving (live) one. • The middle axle may either function as an additional drive axle or for dual steering. • Fifth wheel coupling : Fifth wheel coupling is the swivel mechanism used to attach the trailer to the tractor unit • Articulated vehicle further classified as: • 4 wheeler and 2 wheel trailer (rigid 4 x 2 tractor and single axle 2 articulated trailer) • 6 wheeler tandem drive axle tractor and 4 wheel trailer ( rigid 6 x 4 tractor and tandem axle 4 articulated trailer) • 6 wheeler dual steer axle tractor and six wheel trailer ( rigid 6 x 2 tractor and tri – axle 6 articulated trailer)

16. Side view and underside view of a conventional 18-wheeler semi-trailer truck with an enclosed cargo space. The underside view shows the arrangement of the 18 tires (wheels). • Shown in blue in the underside view are the axles, drive shaft, and differentials. • The legend for labelled parts of the truck is as follows:1. tractor unit2. semi-trailer (detachable)3. engine compartment4. cabin5. sleeper (not present in all trucks)6. air dam7. fuel tanks8. fifth wheel coupling9. enclosed cargo space10. landing gear - legs for when semi-trailer is detached11. tandem axles

17. Typical Engine Configurations – 4 types Front engine, front wheel drive can help with the drive-ability of the vehicle. The engine weight over the driven wheels gives greater traction. This can be particularly useful in adverse weather conditions. Front engine, front wheel drive Front engine, rear wheel drive configuration has the advantage of better weight distribution. However, some traction can be lost because the bulk of the weight is not over the driving wheels. Front engine, rear wheel drive

18. Typical Engine Configurations…. Rear engine, rear wheel drive provides a larger load to the rear driving wheels. However, it can become ‘tail heavy’ which affects handling of the vehicle. It also reduces luggage space (which is now in the front), as the passenger seats need to be moved forward in order to accommodate the engine. Rear engine, rear wheel drive Mid-engine, rear wheel drive engines provide good vehicle handling and good traction at the rear wheels. They are normally found on two-seat sports cars where these factors are important. Mid-engine, rear wheel drive

19. FOUR WHEEL DRIVE • This arrangement is safer because of distribution of the drive to all four wheels. • The sharing of the load between the four wheels during acceleration reduces  the risks of wheel spin specifically on slippery surfaces like snow and mud. • In addition the positive drive to each wheel during braking minimizes the possibility of wheel lock- up. • On an icy road or across off-highway a two-wheel-drive vehicle soon becomes non-drivable due to the loss of grip of one of the driving wheels which causes the wheel to spin.

20. Vehicle System Location - Fuel Systems Fuel tank Fuel pump Fuel injectors Fuel filler cap and neck Fuel filter

21. Vehicle System Location - Suspension System The front strut assemblies typically comprise a spring and a shock absorber. These devices control the suspension stiffness. Rear coil springs Rear shock absorbers Front strut assembly The lower arms allow lateral movement of the suspension system and connect the front hub to the vehicle body. . The rear suspension assemblies also contain springs and shock absorbers. The system shown has a solid rear axle and is known as ‘non-independent rear suspension’. Independent rear suspension systems are available that do not use a solid rear axle Rear hub Front hubs Lower arms

22. Vehicle System Location - Steering System The steering wheel allows the driver to control the direction of the vehicle Steering column Steering rack Front hub The steering column transmits the action of the steering wheel to the steering rack The steering rack changes a turning movement into the side-to-side movement required to turn the wheels Steering wheel The track rod (ball joint) allows vertical and horizontal movement of the steering system Track rod end The front hub connects the steering rack to the wheel

23. Vehicle System Location - Braking System The disc and drum brake assemblies help to bring the vehicle to a stop. Disc brakes can be found on either the front or rear of a vehicle, and drum brakes are normally found on the rear of a vehicle Handbrake Disc brakes typically comprise: a disc, calliper, and brake pads Drum brake assembly Disc brake assembly Drum brakes typically comprise: a brake drum, wheel cylinder and brake shoes The handbrake provides a mechanical linkage to the brakes and can be used to stop the vehicle if the hydraulic system fails. It can also be used to hold the vehicle stationary when it is parked

24. Vehicle System Location - Braking System The master cylinder has a hydraulic piston that provides power to the brakes by pressurizing the brake fluid when the brake pedal is depressed by the driver ABS modulator The brake servo provides an increase in power exerted to the master cylinder, so helping to reduce effort given by the driver at the brake pedal Master cylinder and reservoir The ABS modulator consists of a pump and a number of solenoid valves that control brake pressure to each wheel when the ABS is activated

25. Vehicle System Location – Single Exhaust System Catalytic converter The exhaust manifold connects the exhaust ports of the engine to the exhaust pipe Tailpipe The catalytic converter removes harmful gases from the exhaust fumes, so they are not released into the atmosphere The silencerreduces the noise from the exhaust by dampening pressure pulsations Exhaust manifold Silencers The tailpipe is where the remaining exhaust gas is released outside the vehicle body from the silencer

26. Main parts of the Automobile • The body • The main function of the body is to provide comfort and protection t the passengers besides giving a good look. • The body includes the passenger compartment, the truck, the bumpers, the fenders, the radiator grill, the hood, interior trim, glass and paint.

27. Vehicle Body Components Roof Rear quarter The roof, front wings and rear quarters can be used to help strengthen the vehicle body. Other parts can also help to strengthen the vehicle body e.g. glass, doors, sub-frames, chassis and floor-pan Rear bumper Frontbumper Front wing

28. Parts of the Vehicle Body Boot lid/ Tailgate Bonnet Doors

29. Car body terminology B-PILLAR ROOF A-PILLAR C-PILLAR WINDSHIELD BOOT BONNET GRILLE BUMPER FENDER DOOR GLASS DOOR HANDLES

30. The chassis • The chassis forms the complete operating unit and is capable of running with its own power. • It is an assembly of vehicle without body. • The chassis includes the frame, wheels, axles, springs, shock absorbers, engine, clutch, gearbox, propeller shaft and universal joints, differential and half shafts, steering, brakes and accelerator, fuel tank, storage battery, radiator and silencer.

31. VEHICLE ASSEMBLIES

32. CHASSIS & BODY CONSTRUCTION • Two methods of body and chassis construction, the separate body and chassis construction and the integral construction. • In separate body and chassis construction, the body is fixed to chassis frame by means of a number of body bolts, passing through the base of the body and the frame. • In the integral construction, the body and the chassis frame are combined as one eliminating the mountings. • The integral construction is also called as chassis – less or unibody construction. • Unlike commercial vehicles, which have a separate cab attached to a chassis, car bodies are now mostly integral construction which is frameless mono box construction.

33. BODY ON FRAME

34. MONOCOQUE

35. DIFFERENCE • The benefit is higher load capacity and strength • Disadvantage is the body tends to vibrate easily and the overall vehicle handling and refinement is lower • Used mostly for SUV’s and bigger vehicles • Advantage is less rattles and squeaks are developed. Handling is also better due to the higher body rigidity • Only major drawback is the load carrying capacity is lower • Used mostly in cars

36. FRAME There are two distinct forms of construction in common use: • The conventional pressed steel frame to which all the mechanical units are attached and on which the body is superimposed. • The integral or frameless construction, in which the body structure is so designed as to combine the functions of body and frame, the units normally attached to the frame then being attached directly to the body. • The frameless construction is however possible only in the case of a closed car, since the roof, screen pillars, door pillars and rear panel are essential load – taking parts of the structure. The frameless construction has the following advantages over the conventional framed construction: • Reduced weight and consequent saving in fuel consumption. • During collision the body crumbles, thereby absorbing the shock due to impact and thus providing safety to the passengers. • Lower manufacturing cost. • Compared to framed construction lower body position may be obtained, thus resulting in increased stability of the automobile.

37. Disadvantage of frameless construction • Reduction of strength and durability. • Economical only if frameless construction is adopted in mass production. • Increased cost of repairs in case of damage to body during accidents. • Topless cars are difficult to design with the frameless construction. • Frame construction • A simplified diagram representing the frame shows the longitudinal members A and the members B. • The frame is upswept at the rear and front to accommodate the movement of axles due to springing. It also keeps the chassis height low. • The frame is narrowed down at the front to have a better steering lock, which gives a smaller turning circle. • The extension of the chassis frame ahead of the front axle is called front overhang whereas its extension beyond the rear axle is called rear overhang.

38. SUB FRAMES • Components are mounted on a separate frame called sub-frame. • The sub-frame is further supported by the main frame at three points. • In this way the components are isolated from the effects of twisting and flexing of the main frame. • Advantages of sub-frames are: • The mass of the sub-frame alone helps to damp vibrations. • The provisions of sub-frame simplifies production on the assembly line and facilitates subsequent overhaul or repair.

39. DEFECTS IN FRAMES • The only prominent defect that usually occurs in the frames due to accidents is the alignment fault. • This may be checked by means of plumb line. • The vehicle is placed on a level surface and by suspending plumb line from different points on each side of the frame, their position on the ground is marked • The vehicle is taken away and the diagonals are measured between corresponding points. • These should not differ by more than 7 or 8 mm. • If any of the corresponding diagonals do differ by more than this amount, the frame is out of alignment. • The possible cause then may be one of the following: • The dumb irons or side members may be bent. • Cross members may be buckled. • Some rivets may be loose or broken. • If the damage to the frame members is small, they can be repaired by means of a hydraulic jack and wringing irons. • If the damage is more, the bent frame member may be heated to straighten it. • Alternative may be to cut the damaged part and weld a new one instead.

40. FRAMELESS CONSTRUCTION • In this type of construction heavy side members used in conventional construction are eliminated and the floor is strengthened by cross – members and the body, all welded together.

41. VEHICLE DIMENSIONS • Wheel track – This is transverse distance between the tyre to ground centers on the near – side an the off – side. • Wheel base – This is the longitudinal distance between the centre lines of the front and the rear axles. • Chassis-member cross sections. • Square solid bar. • Round solid bar. • Circular tube with longitudinal slit. • Circular closed tube. • C-section. • Rectangular box section. • Top-hat-section. • I-section. • Channel flitch plate.

42. INTEGRAL CONSTRUCTION • Around 1934, the all-steel body construction was introduced so that a separate frame could be eliminated. • This frameless or integral construction provides a stiff, light construction, which is specifically suitable for mass-produced vehicles. • Since 1945 light cars have used integral construction. When suitably designed the body shell is capable of withstanding the various frame stresses. • The floor and roof panels resist the sagging effect caused by the weight of the occupants. • Since these two members are widely spaced, thin sheet metal is used to form a strong and lightweight box like structure. • To increase torsional stiffness of the body the scuttle at the front is strengthened and behind the rear seat squab cross ties are used or a ribbed metal panel is fitted. • The thickness of the sheet metal depends on the stress to be taken by the panel. Structural members such as sills, rails and pillars are often about 1.1 mm thick, whereas panels such as the roof are 0.9 mm thick. • Component attachment points are reinforced with thicker section. Some cases use a separate sub-frame to mount engine and other members. Sometimes this sub-frame is connected to the body by rubber insulation mountings.

43. INTEGRAL CONSTRUCTION • A very low (0.1 percent) carbon steel is used to provide extremely good ductility required for the pressing of the panels. • The low strength, 278 MN/m2, of this steel requires stiffening of thestructural members, which is achieved by spot welding into position of intricate sections, formed out of thin steel sheet.

44. A modified construction is necessary in case the roof cannot be fully utilized as a compression member. • This situation occurs on drop-head coupe models and where a sunshine roof, or very thin door pillars are used. • To achieve the required strength in these cases a strong under-body frame is used. In addition, the body-shell parts, which are subjected to torsion, are provided with extra stiffness. • A body-shell is normally fabricated either by spot-welding the panels, pillars and pressings together to form a strong box, or by buildings a skeleton or space frame which provides a high structural strength. • To this frame is attached the shell, aluminium or glass-reinforced plastic (GRP) body panels, doors, roof, etc. • Steel is the most common material used for manufacturing of vehicle in high volume, because production costs become lower once the initial investment on body jigs and other facilities has been recovered. • The vibration of the panels, which produces an unwanted noise called drumming, is avoided by fixing a sound-damping material on the inside of the panels. • The driver and passengers are enclosed in a rigid cell for their safety.

45.  The front and rear of this rigid compartment are fixed with sub-frames, which are designed to concertina on impact . • The crumple zones of the body absorb the shock of a collision so that the rate of deceleration experienced by the occupants is reduced.

46. BODY IN WHITE • Body in white or BIW refers to the stage in automotive design or automobile manufacturing in which a car body's sheet metal components have been welded together — but before moving parts (doors, hoods, and deck lids as well as fenders) the motor, chassis sub-assemblies, or trim (glass, seats, upholstery, electronics, etc.) have been added and before painting.

47. BODY IN WHITE ASSEMBLY

48. Body components • Windows and door pillars (3,5,6 and 8). • Windscreen and rear window rails(2). • Cantrails(4). • Roof structure.

49. Window and door pillars (Fig.(3, 5, 6, and 8)) Window screen and door pillars are identified by a letter coding; the front windscreen to door pillars are referred to as A post, the centre side door pillars as BC post and the rear door to quarter panel as D post. These are illustrated in Fig

50. These pillars form the part of the body structure which supports the roof. • The short form A pillar and rear D pillar enclose the windscreen and quarter windows and provide the glazing side channels, whilst the centre BC pillar extends the full height of the passenger compartment from roof to floor and supports the rear side door hinges. • The front and rear pillars act as struts (compressive members) which transfer a proportion of the bending effect, due to underbody sag of the wheelbase, to each end of the cantrails which thereby become reactive struts, opposing horizontal bending of the passenger compartment at floor level. • The central BC pillar however acts as ties (tensile members), transferring some degree of support from the mid-span of the cantrails to the floor structure.