Unit 2 Front and Rear Axles, Steering Sysytem, Wheels and Tyres

B.E Mechanical (PAT.2015)
Automobile Engineering
University of Pune

1. Unit: 2
Front and Rear axle, Steering System
Wheels and Tyres
PreparedBy
Mr.H.D.Gurav(M.EAutomotive,B.EMechanical)
AssistantProfessor
PVGCOENashik
Automobile Engineering (Open Elective)
B.E Mechanical Engineering (Pat. 2015)

2. Syllabus
•Axles: Purpose, requirement and types of front and
rear axle, loads acting on rear axles.
•Wheels and tyres: Wheel construction, alloy wheel,
wheel balancing, type of tyres, tyreconstruction, tyre
materials, factors affecting tyrelife.
•Steering system : Steering mechanism, steering
geometry, cornering force, slip angle, scrub radius,
steering characteristics, steering linkages and gearbox,
power steering, collapsible steering, reversibility of
steering, four wheel steering, wheel alignment.

3. Anaxleisacentralshaftforarotatingwheelorgear.
Onwheeledvehicles,theaxlemaybefixedtothewheels,
rotatingwiththem,orfixedtothevehicle,withthewheels
rotatingaroundtheaxle.
Bearingsorbushingsareprovidedatthemountingpoints
wheretheaxleissupported.
DEFINITION

4. REAR
AXLE
•Full Floating
•Semi Floating
•Three Quarter
Floating
FRONT
AXLE
•Dead Front Axle
•Line Front Axle
STUB
AXLE
•Elliot
•Reversed Elliot
•Lamoine
•Reversed
Lamoine
TYPES OF AXLES

5. Front Axle
•Purpose of Front Axle
–Carry weight
–Facilitate steering
–Absorb shock
–It absorbs torque applied on it due to braking of
vehicle.
•Made up of steel drop forging having 0.4 % of
carbon steel or 1-3% nickel steel.

7. Stub Axle
Main Beam
King Pin
Track Rod

8. •Live axles are used to
transmit power from gear
box to front wheels.
•Live front axles although,
resemble rear axles but they
are different at the ends
where wheels are mounted.
Maruti-800 has line front
axle.
LIVE AXLE

9. •Dead axles are those
axles, which do not
rotate.
•These axles have
sufficient rigidity and
strength to take the
weight.
•The ends of front axle
are suitably designed to
accommodate stub
axles.
DEAD AXLE

10. •Stub axles are connected to the front axle by king pins. Front
wheels are mounted on stub axles arrangement for steering.
Stub axle turns on king pins. King pins is fitted in the front
axle beam eye and is located and locked there by a taper cotter
pin. Stub axles are of four types:
•Elliot
•Reversed Elliot
•Lamoine
•Reversed Lamoine
STUB AXLE

11. Types of front DEAD AXLE
TYPES OF STUB
AXLES

12. •With a semi floating axle, the
axle shaft both carries the
weight and transmits torque
•The wheel is often bolted
directly to the flange on the
axle
•Semi float axles are seen on
cars and light duty trucks
•Semi floats are more limited
in capacity, but lighter and
cheaper to manufacture.
SEMI FLOATING AXLE

13. SEMI FLOATING AXLE

14. •The weight of the axle is
supported by the axle housing-
more specifically, a bearing
spindle attached to the axle
housing, and a set of bearings
in a separate wheel hub.
•Torque is transmitted by a
separate axle shaft that carries
no weight.
•As commonly built, full-
floaters are considerably
heavier, but also much
stronger.
FULL FLOATING AXLE

15. FULL FLOATING AXLE

16. •Thistypeofaxleisacombinationoffullandsemifloating
bearing.
•Inthisbearingislocatingbetweentheaxlecasingandhubaxle
shaftdonothavetowithstandanyshearingorbendingaction
duetotheweightofthevehicle,whicharetakenupbythe
axlecasingthroughhubandbearing.
•Howeverithastotaketheendloadsanddrivingtorque.
•Athreequarterfloatingaxleissameassemifloatingwithone
difference.Theouterbearingismovedtotheoutsideofthe
outerendoftheaxletube,supportinghubassemblyviathe
bearing’soutercircumferenceedge.
THREE QUARTER FLOATING AXLE

17. THREE QUARTER FLOATING AXLE

18. Correct Steering Angle

20. AckermannsSteering Mechanism

21. Steering Geometry
•Camber
•King Pin Inclination
•Castor
•Toe-in or Toe-out
•Combined Angle
•Slip Angle

22. CAMBER
•DEFINITION
•Camber is the tilt of the car wheels
from the vertical.
•Camber is positive if the tilt is outward
at the top.
•Camber is also called as “Wheel rake”.
FRONT VIEW

24. Effect of positive and negative Camber

25. Contd....

26. FRONT VIEW

28. Combined Angle

29. Scrub Radius
Negative: Wheel tends to Toe-In

30. CASTER ANGLE
Amount:-About 3
0
of castor give good results
SIDE VIEW

31. Positive and Negative
CASTER
SIDE VIEW

32. Effects
•Positive Castor:
•Toe-in
•High steering wheel turning Efforts

33. Toe-in
Rear wheel drive vehicle: Small amount of Toe-in is provided

34. Toe-Out

35. Toe-in & Toe-out
TOP VIEW

36. Slip Angle and Cornering Force
Ref: J.Y .Wong(Vehicle Dynamics)

37. Steering System

38. Steering Linkages-Rigid Axle
Suspension

39. Contd...

41. Steering Linkages-Independent
Suspension System

42. Steering Gears
Steering Ratio:
It is the angle turned by the steering wheel to the corresponding turning
angles of the stub axle
They are as follows:
•Worm and wheel steering gear
•Worm and sector steering gear
•Cam and lever / peg steering gear
•Recirculatingball steering gear
•Rack and pinion steering gear.

43. Worm and Wheel Steering Gear

44. Cam and lever / peg steering gear

45. Worm and Nut type

46. Recirculatingball Type

47. Rack and Pinion type