Unit i
- 1. UNIT I VEHICLE STRUCTURE AND ENGINES
- 2. TYPES OF AUTOMOBILES • (i) with respect to the purpose • (a) Passenger vehicles. Ex. Car, bus, jeep, scooter, mopeds and motor cycles • (b) Goods carriers: ex. Trucks and lorries • (ii) weight of the vehicles: • - Heavy weight vehicle- buses, trucks and trailers • - Light weight vehicles - cars, jeeps • - Medium weigh vehicles – minibus and station wagon • (iii) With respect to the fuel: • - Petrol vehicles – scooters, cars motors cycles • - Diesel vehicles - Buses , trucks • Gas vehicles – Coal gas, LPG, CNG vehicles • Electric vehicle – Heavy cranes, battery truck, cars and fork lifts
- 3. • (iv) with respect to capacity: • Heavy transport vehicles – Bus lorries, trucks, tractors • Light transport vehicles _ Car, scooter, mopeds, motor cycles, jeeps • (v) with respect to number of wheels: • Two wheelers – Scooters, mopeds • Four wheelers – car, jeep, buses, truckes • Three wheelers – Auto, tempos • Six wheelers - heavy trucks • (vi) With respect to side of driver seat • - Left hand drive- American, European and UAE • -Right hand drive – Indian vehicles
- 4. • Bullock cart consists of • (i) Frame (ii) wheels & axle • (iii) Yoke (iv) Body or superstructure and platform • These pars can be divided into two main portions • (i) Machine portion (ii)carriage portion
- 6. • Classification of chassis: According to the fitting of engine: - Full-forward – ex cars, mahindra jeeps -semi- forward – Tata Se series of vehicles - Bus chassis – Busses and trucks - Engine at back- Volkswagen cars, Leyland bus of England. - Engine at centre- Royal tiger world master buses of Delhi transport. According to the number of wheels fitted in the vehicles and number of driving wheels:
- 7. • Characteristics of a good chassis: • Fast pickup, strength, safety, durability, dependability, ease of control, quietness, speed, power accessibility, economy of operation low centre of gravity stability load clearance, braking ability, simplicity of lubrication. • Chassis Components: Frame, suspension systems • steering system, braking system, internal combustion engine, clutch, gear box , propeller shaft, universal joint ,differential, springs
- 12. • VEHICLE AERODYNAMICS: • Resistance to vehicle motion: • 1.Air resistance or aerodynamic drag: • A vehicle travelling at a particular speed in air encounters a force resisting its motion. • A) Size of the vehicle (b) shape of the vehicle • C) Speed of the vehicle (d) wind velocity • 2. Gradient resistance: component of the vehicle weight which is parallel to the plane of the road. • 3. Rolling resistance: of tyres on hard surfaces is due to hysteresis in the tyre material. Tyre rolling resistance Road rolling resistance Resistance due to tyre slip angle Resistance due to bearing friction and residual braking
- 13. • Aerodynamics of Automobile body: • Various aerodynamic force acting on the vehicle. • (i) Drag force (Fx): Force of air drag is acting in the direction of vehicle motion with the wind acting along the longitudinal direction axis. • The main causes (i) shape drag (ii)Skin friction drag. • (ii) Lift force(Fz):Aerodynamics lift force is the vertical component of the resultant force caused by the pressure distribution on the body. • (iii) Cross wind force (Fy):It is acting in the lateral direction on the side of the vehicle. • These forces acting at the centre of pressure instead of centre of gravity & various cause of moments
- 14. • (i)Pitching moment (My): is caused by the drag force Fx or lift force Fz about Y axis. This moment makes the rear wheels lift off from the ground and further it reduces the available traction. • (ii) Yawing moment(Mz): Cross wind force Fy about Z axis • (iii) Rolling moment(Mx): Cross wind force Fy about X axis •