This presentation is made as per Dr. Babasaheb Ambedkar Technological University, lonere,Raigadh,Maharashtra. syllabus. Useful for mechanical, automobile engineering students. SO learn, do study . suggestions are welcome

1. Prof. S .S .Petkar, AMGOI

2. Vehicle Specification

4. Main Components of Automobile
Automobile
Chases
Power Plant,
Bearings, Gear box
Brakes, Steering,
Suspension
Body
Boot space,
Radiator, Hood

5. Main Components of Articulated Automobile
• An articulated vehicle is a
large vehicle made in two
separate sections, a tractor
and a trailer, connected by a
pivoted bar.
• These vehicles can carry
heavy loads and can take
sharp turns.
• An articulated truck is a
vehicle that is most
commonly used in
construction work

6. Main Components of Articulated Automobile
tractor

8. Engine Cylinder Arrangement
Cylinder arrangement

9. Engine – Drive Arrangement
Front wheel drive

10. Rear wheel drive

11. Four wheel drive

12. Tractive Effort and Traction
• It is the driving force which is available at the
contact between road and wheel tires
• Traction is the ability of wheels to transmit the
tractive effort without slipping.
• Hence tractive effort will never exceed the traction

15. Power for Propulsion
1) The motion of a vehicle moving on a road is resisted by aerodynamic forces,
known as wind or air resistance,
2) road resistance which is generally termed as rolling resistance.
3) In addition to these two types of resistances, the vehicle has to overcome grade
resistance when it moves up on a gradient, because the weight of the vehicle is to
be lifted through a vertical distance.
Hence, the power required to propel a vehicle is proportional to the total
resistance to its motion and the speed.

16. Power for Propulsion
<<<<< Hence required engine power

17. Air Resistance
1) This is the resistance offered by
air to the movement of a vehicle.
2) The air resistance has an
influence on the performance, ride
and stability of the vehicle and
depends upon the size and shape of
the body of the vehicle, its speed
and the wind velocity.

18. Rolling Resistance
• The magnitude of
rolling resistance
depends mainly on
(a) the nature of road
surface,
(b) the types of tyre
(c) the weight of the
vehicle
(d) the speed of the
vehicle.
It is given by
Rr= (a+bV) W
where V = speed of the vehicle,
km/hr.
Mean values of a and b are 0.015 and
0.00016 respectively.
W = total weight of the vehicle, N
The rolling resistance is expressed as
Rr= KW
K = constant of rolling resistance and
depends on the nature of road surface and
types of tyres = 0.0059
for good roads = 0.18
for loose sand roads = 0.015

19. Grade Resistance
• The component of the weight
of the vehicle parallel to the
gradient on which it moves is
termed as ‘grade resistance’.
• it depends upon the
steepness of the grade.
• If the gradient is expressed as
1 in 5, it means that for every
5 meters the vehicle moves, it
is lifted up by 1 metre.
• Hence, grade resistance is
expressed as
• Rg= W Sin ϴ

20. Utilization of excess force available for different purposes:-
1) Draw bar Pull:-
• When excess power is
fully utilized for pulling
extra load attached to the
vehicle, then maximum
draw bar pull is equal to
tractive effort minus total
resistance
• Draw Bar Pull= F-R
2) Gradability:-
• It is the car ability to
climb slopes.
• It is measured in
percentage or degrees
• Grad.= 100 (F-R) /W
• W= Wt. of automobile

21. 3) Acceleration
• When the vehicle is
accelerated its rotating parts
are also accelerated
depending upon their M.I. &
Gear ratio in drive line.
• Due to this wt. of vehicle
increased, this is known as
“Effective wt. “
• By utilizing excess power available
from engine, vehicle is accelerated
1 𝐹 − 𝑅
f= ---------------------
Me
f = Acceleration of vehicle
Me= Effective mass
Pex.= (Pe-Preq)x 3600x ἠT x 3600/V
Pex= Excess power

22. Performance Curve
• Indicated Power (I.P.)
• Brake Power (B.P.)
• Torque
• Specific Fuel Consumption :-
– Deviding total fuel consumption per hr / power devp.
– (ISFC and BSFC)
• Frictional Power:-
it is difference between IP & BP.

23. Performance Curve
Variation of IP,BP,T,FP with Speed @
Full Throttle condition
1) As FP becomes larger
IP increases
& BP drops
2) Engine Speed for
max. T & max. P
are not same

24. Performance Curve
1) Initially SFC decreases & reaches
some
min. value & then gain.
2) Thus the best engine speed is the one
to min. SFC, where power is low.

25. Power curve, Torque curve, BSFC curve
Engine Specification
N1 and N2 are the speed of different engines hence max BP is different
P = Point at which B.P. is high. wrt Speed N1 & N2

26. Torque Curve
• This curve is generally flatter than power curve.
• T first increases with increase in speed, reaches
max. and then decreasing.
• Besides the high maximum torque value, shape
of the torque curve and the speed at which max
torque occurs are also equally imp.

27. BSFC curve
It may be seen that ,
curve has an inverse
relationship with torque
curve.
Also the minimum of this
curve occurs nearly at
the same engine rpm as
the max of engine torque

28. How to improve engine performance??
• By increasing input energy (Fuel in/time), 4valves
• By increasing engine efficiency:- Compression ratio up
• Supercharging and turbocharging
• Polish intake manifold to minimize resistance to
intake air
• 2 exhaust valve in each cylinder. E.g. all car, Pulsar
135 LS, LML Adreno.
• Use bigger tail pipes, free flowing mufflers