SAE-ECOKART Final Report

Visvesvaraya Technological University Belgaum

Minor Project Report

SAE Eco kart Submitted in partial fulfilment of the requirements of the Bachelor Degree of

Bachelor of Engineering In

Automobile Engineering Submitted By

Aditya Jha 2BV12AU001

Durbar Ghosh 2BV12AU014

Kunal Habib 2BV12AU021 Sindhoor Hegde 2BV12AU048

Under the Guidance

of Dr. Siddhalingeshwar I.G.

Department of Automobile Engineering

B. V. Bhoomaraddi College of Engineering & Technology, Hubli-580031

(An Autonomous Institution affiliated to VTU, Belgaum)

2014-2015

DEPT. OF AUTOMOBILE ENGINEERING, BVBCET Page 2

K.L.E SOCIETY’S

B.V.BHOOMRADDI COLLEGE OF ENGINEERING & TECHNOLOGY,

HUBLI-580031

(An Autonomous Institution Affiliated to VTU, Belgaum)

2014 - 2015

DEPARTMENT OF AUTOMOBILE ENGINEERING

CERTIFICATE

This is to certify that the report titled “SAE ECO-KART” is a bonafide record of

the Minor Project carried successfully by the students:

Aditya Jha (2BV12AU001)

Durbar Ghosh (2BV12AU014)

Kunal Habib (2BV12AU021)

Sindhoor Hegde (2BV12AU048)

As a part of Minor Project(AUP301) of Sixth Semester Automobile

Engineering syllabus, for the year 2014-2015.

Guide H.O.D Principal

Dr. Siddhalingeshwar I.G. Dr. Anil Badiger Dr. Ashok S. Shettar

Name of the Examiners Signature with date

1.

2


SAE ECO KART


ACKNOWLEDGEMENTS

Firstly we would like to thank AUTOMOBILE Engineering Department,

B.V.B.C.E.T for giving us this great opportunity to carry out this Minor Project.

We are very grateful to the Review Committee, Mr. Aditya M. Deshpande, Dr.

Siddhalingeshwar I.G. and Nagaraj Ekabote, our project would never be a success

if they had not supported us. We like to express our sincere regards to our project

guide Dr. Siddhalingeshwar I.G. who has guided and helped us in every possible

manner throughout the journey. We are very thankful to our Prof. Nagaraj

Ekabote who taught us and helped us for learning the software and tools for

successfully performing analysis for our project, and Prof. Balachandra Halemani

who helped us in learning tools for designing. Also we would like to thank Mr.

Ravikiran Murthy and his team for helping us out in the technical issues. We

express our gratitude to all other teaching faculty of Automobile Department for

their kind support. Lastly we would like thank all the persons directly or indirectly

involved in success of our project.


CONTENTS PAGES

1. Introduction to ECO-KART 9

1.1. Objectives for the design 10

1.2. Major Components of Eco Kart: 10

2. Electrical System 11

2.1. Battery 11

2.2. Controller 14

2.3. Pulse-Width Modulator 15

2.4. Throttle or Speed Control 16

2.5. Forward & Reverse 17

3. POWER TRAIN 18

3.1. Motor 18

3.2. Calculations for Battery discharge. 18

3.3. Drive Train 19

3.4. Calculations of speed of the vehicle. 20

3.5. Calculation for size of Power shaft 22

3.6. Gradability 23

4. Steering:

4.1. Introduction 24

4.2. Ackermann steering geometry 24

4.2.1. Advantages of Ackermann steering 25

4.2.2. Design & choice of geometry 25

4.3. 27

4.3.1. Toe in/out setting 27

4.3.2. Ackerman 27

4.3.3. Caster 27

4.3.4. Camber 27

4.3.5. Front width 27

4.4. Steering parts Creo-parametric 2.0 model 28

5. Tyres: 34

5.1. Available tyres 34

5.2. General setup condition for Eco-kart 35

6. Braking System: 36

6.1. Abstract ` 36

6.2. Objectives 36

6.3. 36

6.3.1. Requirements 36

6.3.2. Different Conditions 36

6.4. Brake Subsystems 37


6.4.1. Braking Components & Configurations 37

6.5. Braking System Design 38

6.5.1. Master cylinder 38

6.5.2. Brake rotors 39

6.5.3. Brake pedal 39

6.5.4. Brake fluid 41

6.6. Kinematics of braking 43

6.6.1. Assumptions 43

6.6.2. Typical Measured Deceleration time-history 43

6.6.3. Retardation Force 43

6.6.4. Load Transfer 44

6.7. Brake calculations 45

6.7.1. Brake pedal 45

6.8. Vehicle Dynamics 45

6.8.1. Static axle load distribution 45

6.8.2. Relative centre of gravity height 45

6.8.3. Dynamic axle loads 46

6.8.4. Wheel lock 47

6.8.5. Brake torque 47

6.8.6. Foundation brake 47

6.8.7. Clamp Load 48

7. Frame 52

7.1. Introduction 52

7.2. Objectives 52

7.3. Design of frame 52

7.3.1. Safety 52

7.3.2. Ergonomics and comfort 52

7.3.3. Dimensions 53

7.3.4. Material selection 54

7.3.5. Structural considerations 57

7.3.6. Accessibility 58

7.3.7. Manufacturability 58

7.3.8. Body & floor pan 58

7.4. Model & Analysis 59

7.4.1. Design alternatives 59

7.4.2. Static Load 60

7.4.3. Frontal Impact 62

8. Assembly & Mountings 64

8.1. Rods & Fasteners 64

8.2. Mounts 64

8.3. Innovation in bumper design 68

8.4. Weight Distribution 69

9. References 70


LIST OF FIGURES/TABLES/GRAPHS PAGES

1. Fig 1: World record Fastest Acceleration 9

2. Fig 2.1: battery 12

3. Fig 2.2: Schematic of controller 14

4. Fig 2.3: Controller 14

5. Fig 2.4: Schematic of PWM 15

6. Fig 2.5: Layout of Motor controller 17

7. Fig 3.1: Motor 18

8. Table 3.1: CVT vs Chain sprocket transmission 19

9. Fig 4.1. Ackerman steering 24

10. Fig 4.2. Ackerman steering Geometry 26

11. Fig 4.3. Steering assembly 28

12. Fig 4.4 Tie rod parts 28

13. Fig 4.5 Tie rod and Ackerman arm joint 29

14. Fig 4.6. Steering column with Drop arm 29

15. Fig 4.7 Steering Wheel 29

16. Fig 4.8. Left stub axle dimensions 30

17. Fig 4.9. ISO-7379 Bolt & Nut 30

18. Fig 4.10. Inner wheel angle 31

19. Fig 4.11. Inner wheel turning radius 31

20. Fig 4.12. Outer wheel angle 32

21. Fig. 4.13 Outer wheel turning radius 32

22. Table. 5.1. Available tyres 34

23. Table. 5.2. Dimensions of available tyres 34

24. Fig. 6.1. Brake system layout 38

25. Fig. 6.2. Brake master cylinder 38

26. Fig. 6.3. Rotor 39

27. Fig. 6.4. Brake pedal 40

28. Table. 6.1. List of popular mass produced brake master cylinder along with diameter and their areas. 41 29. Table 6.2. Brake system assembly parts 42

30. Graph 6.1. Deceleration vs Time 43

31. Graph 6.2. Velocity vs Time 43

32. Graph 6.3. Displacement vs time 43

33. Fig. 6.5: Thermal 50

34. Fig. 6.6: Stress 51


35. Fig. 6.7: Strain 51

36. Fig. 6.8: Total Deformation 51

37. Fig. 7.1. Seeting position & dimension measurement 53

38. Fig. 7.2. Dimensions of frame ( top view ) 53

39. Fig. 7.3. Dimensions of frame (side view ) 54

40. Table 7.1. Properties of materials 55

41. Table. 7.2. Tubes of available size 56

42. Fig. 7.4. Iteration 1 59



45. Fig. 7.7. Stress 60

46. Fig. 7.8. Maximum Deformation 60

47. Fig. 7.9. Factor of Safety 61

48. Fig. 7.10. Forces acting while impact 61

49. Fig. 7.11. Stress 62

50. Fig. 7.12. Maximum Deformation 62

51. Fig. 7.13. Factor of Safety 63

52. Fig. 8.1. Front Bumper 68

53. Fig. 8.2. Distances of Weights from front axle 69


1. Introduction to ECO-KART:

An SAE Eco Kart vehicle is a single-seat, motor driven go kart building

competition. Undergraduate students from multiple academic fields

collaborated to design and manufacture a safe, high-performance, cost-efficient

Baja vehicle to serve as a prototype for mass production. The students utilized

and refined both financial procedures and engineering analyses to complete this

objective while Strictly following the prescribed SAE rules.

The main intention behind that is to allow students to apply theory learnt class

to a practical situation. Provide students a favour of working in a simulated

industry environment. Students get an opportunity to apply theory learned in

classes to a practical engineering project. Students the knowledge and

experience in working in a simulated industry environment. Students are

challenged to provide an innovative design that meets the criteria of the design

competition.

Fig 1: World record Fastest Acceleration [0-60mph in 3.4 sec]


1.1. Objectives for the design

1. 100% pollution free operation,

2. Avoiding uses of conventional fossil fuel,

3. Safety and ergonomic consideration,

4. Maneuverability,

5. Energy efficient[light weight, aero dynamics],

6. Range of operation,

7. Aesthetics,

8. Easily accessible and repairable

9. Team identity and design novelty [Style, name, logo]

1.2. Major Components of Eco Kart:

1. Power Unit Motor

Motor controller

Battery

Battery Management System

Transmission

2. Wheels & Tires

3. Steering System

4. Braking System

5. Frame

6. Body design

7. Safety Equipments


2. Electrical system

2.1. Battery: The Eco kart vehicle is fully powered by electric battery. The below

details gives the full specification of Battery:-

Objectives of Battery:-

It should have long life

It should have less weight

It should give power required continuously for longer period.

• It should be charged easily and quickly after discharging.

• Cost effective.

• Safety.

• 12V, 42 A should be given out of each battery.

• Non-toxic.

• Compact and low weight in size.

• Easily available.

• Easily replaceable, repairable

Lead acid

battery

Lithium-ion

battery

Nickel-

cadmium

battery

Cost $40-65 $120-264 $69-120

No.of cells req. 12*4 12*2 12*1

Battery life

(cycles life)

300 500+ 1550+

Weight 25kg/1kWhr 6.7kg/1kWhr 5.6kg/1kWhr

Shelf life 12 months 12 months 6 months

Voltage range 2.1 V 3.7 V 1.2 V

Size 14 litres /1kWhr 2.5 litres/1kWhr 3.2 litres/1kWhr


Availability Easily avail Delivery at 2-3

days from

ordering

Difficult to gain

has much

powerful

Overcharging

tolerance

moderate high Very low

Table 2.1. Specifications of batteries

We have chosen battery from specification metrics table due to its efficiency of

quick charging and efficiency to discharge more power for longer time.

Chemical equation:

C + LiCoO2 LiC6 + Li0.5CoO2

Fig 2.1: battery

Battery type- Lithium-ion

Battery Voltage=12 V

No. of batteries required at one

time=4

Nominal voltage: 12.8V

Typical capacity: 20Ah

Max continuous discharge current

20A

Max pulse discharge current : 60A

Work voltage range: 9.2V~14.6V

Size: 180*75*165mm

Weight: 2.4kg each

The Batteries are connected in series so that all the 4 battery equals one

battery of 48V of 80Ah of current.


The Battery is connected to Battery safety system. It is installed so as to

protect the electrical systems and equipments from fluctuating voltages released

from the battery.

The Battery safety system consists of:-

1. Main switch.

2. Ignition switch.

3. Fuse.

4. Miniature circuit board.

5. Regulator of nominal voltage.

6. Contactor

Along with these, the system consists of KILL SWITCHES which is

connected before main switch near the driver as emergency to stop the flow of

current to electrical equipments.

The layout of Battery management system is given below:-

Battery

MAIN SWITCH

MINIATURE CIRCUIT BOARD

CONTACTOR

FUSE

REGULATOR

CONTROLLER

BRAKE LIGHT

POTENTIOMETER

BR

AK

E

PED

AL&

HA

ND

BR

AK

E

Ignition Switch


2.2. CONTROLLER

Objectives of motor control • Sustain fluctuating current and voltages of battery input and give a constant desired

output current.

• Throttle controlling

• Should be able to safeguard the motor by unnatural currents

• Cost effective

• Highly efficient

• Easily and cheaply available

• Should be used for multi purpose.

The controller is system which controls the speed and direction of rotation

of the Motor. It has a circuit board where a number of nominal capacity

capacitors, circuit links, modules etc., this controller connects the Motor in order

to operate it at required speed using the potentiometer signal according to given

Throttle.

The schematic circuit of Controller. The controller unit figure is shown below:-

Fig 2.2: Schematic of controller Fig 2.3: Controller


The specification of the controller is given below:-

Voltage - 48V

Current-35-42amp

Standby Battery Current: < 0.5mA.

5V Sensor Supply Current: 40mA.

Size: 122x87x32mm

Power requirement:10-50VDC

Rated current: 60A(Maximum

output current)

Frequency:15000HZ

Control Motor Power : 0.01-3000W,

Analogue Brake and Throttle Input:

05 Volts.

Motor Current Limit, 1 minute: 100A.

Motor Current Limit,continuous: 60A

.

2.3. Pulse-Width Modulator

The Controller contains a Pulse-width modulator circuit which controls the

fluctuating input voltages into mean output voltages.

Pulse Width Modulation circuit that is used to control the speed of the

motor by means of varying voltage supply to it. The Pulse Width Modulation is

connected to the

motor’s positive terminal and the negative is grounded.

The fig of Circuit (a) is shown below:-

Fig 2.4: Schematic of pulse width modulator

a


Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is

a modulation technique that conforms the width of the pulse, formally the pulse

duration, based on modulator signal information. Although this modulation

technique can be used to encode information for transmission, its main use is to

allow the control of the power supplied to electrical devices, especially to

inertial loads such as motor. The average value of voltage (and current) fed to

the load is controlled by turning the switch between supply and load on and off

at a fast pace.

The longer the switch is on compared to the off periods, the higher the

power supplied to the load is.

Pulse Width Modulation, as it applies to motor control is a way of

delivering energy through a succession of pulses rather than a continuously

varying analog signal. By increasing or decreasing pulse width, the controller

regulates energy flow to the motor shaft. The motor’s own inductance acts like a

filter, storing energy during the ‘ON’ Cycle while releasing it at a rate

corresponding to the input or reference signal. In other words, energy flows into

the load not so much the switching frequency, but at the reference frequency.

PWM is somewhat like pushing a playground style merry go round. The

energy of each push is stored in the inertia of the heavy platform, which

accelerates gradually with harder, more frequent, or longer lasting pushes. The

riders receive the kinetic energy in a very different manner than how it is

applied.

2.4. Throttle or Speed Control

The speed of the motor rotation is controlled by the motor controller

circuit with a input electrical signal from the potentiometer. This potentiometer

converts mechanical signal into electrical signal by actuating the potentiometer

which is been powered by battery. When the throttle is varied by the driver due

to the amount of actuation of the potentiometer the mechanical signal is

converted into electrical signal and is given to PULSE-WIDTH

MODULATOR.

In controller the circuit is designed in such a way that the amount of

voltage acquired by the electronic circuit is directly proportional current flown

to motor at that proportionate.


2.5. Forward & Reverse

The controller has the function of converting the polarities of the current

so as to change the direction of rotation of the motor. A switch to change the

polarity is been given on the Controller circuit itself.

Fig 2.5: The layout of Motor Controller


3. POWER TRAIN

In Eco-kart the power train includes the Motor and there-after it connects to

Transmission system.

3.1. MOTOR

The important component of the eco-kart and also the powertrain system

which is used for propelling of the vehicle. The motor specification is given

below:-

Rated Power (W) -- 3000

Rated Voltage (V) -- 48

Speed Range (rpm) -- 20003500

Efficiency (%) -- >80

Noise (dB) -- <65

Loading--110kg

Peak Torque--12.5Nm@2500rpm

Weight (kg) -- 5

Fig 3.1: Motor

3.2. Calculations for Battery discharge.

As all the electrical components of the vehicle is been listed the battery

discharge is to be determined respective of time


To calculate the discharge ,

Battery discharge TIME =

battery discharge ampere hour

total currentuswd by the components

⁄

=80/(potentiometer +controller & motor + brake lights)

= 80/ (2+40+5)

= 1.70 hr = 1hr 42min

3.3. DRIVE TRAIN

The Drive train of this vehicle consists of transmission system and a

rear shaft with justified bearing to the power shaft.

Transmission -

Comparison CVT Chain sprocket

Power Less power loss due to

precision manufacturing

{+}

Power losses due to

custom non- accurate

manufacturing

Weight More Less {+}

Torque availability More{+} Less

Speed Less compared to

Sprocket

More{+}

Gear ratios Variable {+} Fixed

Shifting mechanism Automatic{+} Derailleur shifter

(manual)

Table 3.1. Continuously Variable Transmission -VS- Chain sprocket variable

gear transmission.


Thus, from above chart it is decided that CVT to be used as the transmission

system.

CVT used - Belt type, Scooty pep.

CVT ratio @ different speeds

@1300 rpm = 22.11

@1700 rpm = 16.23

@2000 rpm = 8.997

@2500 rpm = 6.33

@3500 rpm = 4.884

The Motor shaft is directly connected to CVT Driver wheel so as to

reduce Primary reduction ratio to 1. Now the CVT through Belt drive runs the

Driven Wheel. The Driven has an advantage of connecting power shaft through

itself. This is an innovation of connecting Power shaft directly to the rotating

shaft by welding and other joining process without disturbing the variable

wheel of CVT and Clutch assembly.

The Power shaft is then connected to the Rear Wheels with support of

bearings of justified series no.

3.4. Calculations of speed of the vehicle.

1. Motor RPM : 1300 rpm

Wheel diameter : 11 inch (0.2794m)

Primary Reduction = 1

CVT input RPM= 1300 RPM

CVT Ratio at 1300 RPM is 22.11

Power shaft rpm = 1300/22.11

=58.79 RPM


Speed (Kmph) = Power shaft rpm * 𝜋* Wheel Diameter* 60/1000

=58.79 *3.14*0.2794*60*10-3

= 3.09 Kmph.


Wheel diameter=0.2749

Primary reduction= 1

CVT input rpm = 2500 rpm

CVT ratio at 2500 rpm =6.33


= 379.70 RPM

Speed (Kmph) = Power shaft rpm * 𝜋* Wheel Dia * 60/1000

=379.70*3.14*0.2794*60*10-3

=19.98 Kmph.


Wheel diameter=0.2749

Primary reduction= 1

CVT input rpm = 3500 rpm

CVT ratio at 3500 rpm =4.884


=716.625 RPM

Speed (Kmph) = Power shaft rpm * 𝜋* Wheel Dia * 60/1000

=716.625*3.14*0.2794*60*10-3

= 39.85Kmph.


Torque on the wheels

The maximum motor torque = 12.5Nm Transmission efficiency = 70% = 0.7

Drive torque (Nm) = Motor Torque * combined gear ratio * transmission

efficiency

Combined gear ratio = Primary reduction * CVT Ratio

1) @1300 rpm

Drive Torque = 12.0* 1 * 22.11 * 0.7 = 185.724 N-m

2) @ 2000 rpm

Drive Torque =12.0* 1 * 8.997*0.7 =75.574 N-m

3) @ 3500rpm

Drive Torque =12.0*1*4.884*0.7 = 41.02 N-m

3.5. Calculation for size of Power shaft

The power shaft size is available at standard size based upon its inner

thickness and outer diameter. The material is AISI/SAE-1080 stainless steel.

Thus formula to find Diameter of Power shaft is

𝜏

𝑟 =

𝑇

𝐽

𝜏= Shear Stress= 3.2MPa

T=Torque supplied = 185.724 N/mm

J= Polar moment of Inertia

r= radius of the shaft

3.2

𝑟 =

185.724

𝜋∗𝑟^4/32

r = 18 .10 mm Outer diameter = 36.20 mm

But, the nearest available safe size of the shaft is 38.10 mm having thickness of

6mm.


Vehicle Tractive Effort (or) Drive Torque

Drive Force = Drive torque / Wheel Radius

Calculation

1) 185.724/ 0.2794 = 664.72 N

2) 75.574 / 0.2794 = 270.48 N

3) 41.02 / 0.2794 = 146.81 N

3.6. Gradability

Drive force = mg sin Ɵz

m = 140 kg

g = 9.81 m/s-2

Ɵ = sin-1 ( Drive force / mg )

Calculation

Ɵ = sin-1( 664.72 / (140 * 9.81))

=28.94

Ɵ = sin-1( 270.48 / (140 * 9.81))

=11.35o

Ɵ = sin-1( 146.81 / (140 * 9.81))

=6.1


4. Steering:

4.1. Introduction:

Steering is the term applied to the collection of components, linkages, etc. which will allow

a vehicle to follow the desired course. Generally Steering used in an Go-kart is a simple linkage

type Ackerman steering. Ackerman Steering Principle describes the relationship between the

front wheels of a vehicle as they relate to each other when in a turn. The inner wheel will be

traveling in a smaller diameter circle than the outer wheel. All the wheels should move around

a common point.

When a car enters a corner, the inner wheels will cover a shorter radius than the outer

wheels. This is the explanation why the front wheels of the car do not point in the same

direction.

The Ackermann principle describes how the steering must be designed in order to allow

both of the front wheels follow a proper arc path.

Proper steering system reduces undue stress and heat to the front wheel and tires.

4.2. Ackermann steering geometry:

It is a geometric arrangement of linkages in the steering of a car or other vehicle designed to

solve the problem of wheels on the inside and outside of a turn needing to trace out circles of

different radius.

Fig 4.1: Ackermann steering


4.2.1. Advantages

The intention of Ackermann geometry is to avoid the need for tyres to slip sideways when

following the path around a curve. The geometrical solution to this is for all wheels to have

their axles arranged as radii of a circle with a common centre point. As the rear wheels are

fixed, this centre point must be on a line extended from the rear axle. Intersecting the axes of

the front wheels on this line as well requires that the inside front wheel is turned, when steering,

through a greater angle than the outside wheel.

Rather than the preceding "turntable" steering, where both front wheels turned around a

common pivot, each wheel gained its own pivot, close to its own hub. While more complex,

this arrangement enhances controllability by avoiding large inputs from road surface variations

being applied to the end of a long lever arm, as well as greatly reducing the fore-and-aft travel

of the steered wheels. A linkage between these hubs pivots the two wheels together, and by

careful arrangement of the linkage dimensions the Ackermann geometry could be

approximated. This was achieved by making the linkage not a simple parallelogram, but by

making the length of the track rod (the moving link between the hubs) shorter than that of the

axle, so that the steering arms of the hubs appeared to "toe out". As the steering moved, the

wheels turned according to Ackermann, with the inner wheel turning further. If the track rod

is placed ahead of the axle, it should instead be longer in comparison, thus preserving this

same "toe out".

4.2.2. DESIGN AND CHOICE OF GEOMETRY

A simple approximation to perfect Ackermann steering geometry may be generated by

moving the steering pivot points inward so as to lie on a line drawn between the

steering kingpins and the centre of the rear axle. The steering pivot points are joined by a rigid

bar called the tie rod which can also be part of the steering mechanism, in the form of a rack

and pinion for instance. With perfect Ackermann, at any angle of steering, the centre point of

all of the circles traced by all wheels will lie at a common point. Note that this may be difficult

to arrange in practice with simple linkages, and designers are advised to draw or analyze their

steering systems over the full range of steering angles.

Modern cars do not use pure Ackermann steering, partly because it ignores important

dynamic and compliant effects, but the principle is sound for low-speed maneuvers. Some race

cars use reverse Ackermann geometry to compensate for the large difference in slip angle

between the inner and outer front tyres while cornering at high speed. The use of such

geometry helps reduce tyre temperatures during high-speed cornering but compromises

performance in low-speed maneuvers.


Fig 4.2: Ackermann steering geometry

The steering system used in our vehicle has its tie rod directly connected to the steering rod in

the ratio of 1:1. The Ackermann angle of this type of steering is calculated as follows:

β=tan−1((𝑇𝑟𝑎𝑐𝑘 𝑤𝑖𝑑𝑡ℎ)/2

𝑊ℎ𝑒𝑒𝑙 𝑏𝑎𝑠𝑒)

Where, β=Ackermann angle

From the below equation we can calculate the length of the Ackermann arm, the equation is

given by as follows

(Track width) - (2*Ackermann arm)=sin 𝛽

The value of turning radius is to be assumed. Also the values of track width and wheel base is

given. Substituting these values, the length of Ackermann arm is found. Now the values of

inner and outer angles are calculated as follows

R=(𝑅𝐼2 + 𝑇𝑊2)0.5

RI=(𝑇𝑊

tan 𝛼2)+(

𝑊𝐵

2)

Outer angle 𝛼2= (1

tan 𝛼1)+(

1

tan 𝛼1)=

𝑊𝐵

𝑇𝑊

Inner angle 𝛼1=

Track Width (TW) = 750mm

Wheel Base (WB) = 1200mm


Inner Angle = 30 degree

Outer Angle = 23 degree

Turning radius of inner wheel, 𝑅𝑖 = 2400mm

Turning radius of outer wheel, 𝑅𝑜 = 3072mm

Overall turning radius of the whole cart = 2525mm

Ackermann angle = 17.35 degree

4.3.1. Toe in/out setting

Toe setting will affect weight distribution, top speed and cornering response .the more toe in

or out, the slower the top speed becomes due to excessive drag by tires .despite this negative

effect, increase the toe out can have some benefits, for eg. increase toe out will increase initial

cornering response, thus giving the driver a better turn into corner and reducing understeer.

4.3.2. Ackerman

Ackerman steering makes the front tires turn at different rates for eg. the front inside tire will

turn faster than the outside tire when turning into a corner.

4.3.3. Caster

Caster affects the grip of both the front and rear of the cart .it does this by transferring weight

to the opposite rear wheel during cornering. if caster is decreased the kart will be easier to

steer

4.3.4. Camber

Camber is measurement by how far the front are leaning in or out as viewed from the front

of the kart.

4.3.5. Front width

The most common adjustment made to change the handling of kart is by working with its

front track, or front-end width widening the front track will create more of a jacking effect

when the wheels are turned .this will result in more front end grip and quicker turn in.

narrowing the front track will have the opposite effect. This result in slower in and less front

end bite.


4.4. Steering Parts Creo Parametric 2.0 model:

Fig 4.3: Steering Assembly

Fig 4.4: Tie rod parts


Fig 4.5: Tie rod and Ackermann arm joint

Fig 4.6: Steering column with drop arm Fig 4.7: Steering wheel


Fig 4.8: Left stub axle dimensions [all dimensions are in mm]

Fig 4.9: ISO 7379_M10_×_20 Bolt and Nut [all dimensions are in mm]


These figures below shows how the dimensions have been taken.

Fig 4.10. Inner wheel turns 30O

Fig 4.11. Inner wheel turning radius


Fig 4.12. Outer wheel angle of turn

Fig 4.13. Outer wheel turning radius


Fig 4.14. Turning radius of center of kart

Fig 4.15. Turning radius of midpoint of rear axle


5. TYRES:

5.1. Available tyres

10x4.50-5 KART 3

10x4.50-5 KART2

11x6.00-5 KART1

11x7.10-5 KART 3

11x7.10-5 KART1

10x4.00-5 RAINKART

11x6.00-5 RAINKART

– slick tyre for front use

– slick tyre for front use

– slick tyre for rear use



– tread pattern tyre for front use

– tread pattern tyre for rear use

Table 5.1. Available Tyres

Requirements for tyres for kart

It should be of small size.

It should have less friction coefficient with respect to road.

It should be durable

Cost of tyres should be minimum.

Radius of tyres should not be more than 10 inch.

Kart tyres have dimension as follows:

SIZE WIDTH (mm)

DIAMETER (mm)

RIM (mm)

10X4.00-5

RAINKART

123 250 4.00x5

10X4.50-5

KART2

133 264 4.50x5

10X4.50-5

KART 3

132 262 4.50x5

11X6.00-5 RAINKART

180 270 6.00x5

11X6.00-5 KART1

184 282 6.00x5

11X7.10-5 KART1

206 282 8.00x5

11X7.10-5

KART3

210 278 8.00x

Table 5.2. Dimensions of tyres available


As per our requirement tyre selected is 10x4.50x5 slick tyre for front, and

11x7.10x5 for rear.

5.2. General setup condition for eco kart

Chassis altitude should be in slope from rear to front. Rear should be slightly higher than

the front.

Weight distribution should be 40-45% front and 55-60% rear and 50-50 % side.

Toe should be set out 1/16” to 1/8”-(1-3mm).

More caster is needed over the weekend to fight the tyre wear and loss of grip.

Front bumper should be of less weight.

Tyres should have less grip.


6. BRAKING SYSTEM:

6.1. ABSTRACT

The purpose of this project is to design a braking system for a SAE Eco-cart vehicle that can

produce adequate braking force to meet competition regulations while being as light weight as

possible. The system should also limit un-sprung weight to help improve manoeuvrability.

Similar products and design of components will be researched for this project. A budget,

timeline, proof of design and testing will also be looked at in this report.

6.2. BRAKE SYSTEM

OBJECTIVE - Design a braking system that can produce more than adequate braking force to

meet SAE Eco-Cart competition regulations while being as light weight as possible. The

system should also limit un-sprung weight to help improve manoeuvrability.

6.3. Braking System

6.3.1 Requirements –

Decelerate in a controlled repeatable manner.

Help maintain constant speed.

Hold vehicle stationary on a flat or on a gradient.

6.3.2 Different condition in which brake system should work properly:-

Slippery, wet and dry roads.

Rough or smooth road.

Split friction surfaces.

Straight line braking or when braking on a curve.

Wet or dry brakes.

New or worn linings.

Laden or unladen vehicle.

Frequent or infrequent applications of short or lengthy duration.

High or low rates of deceleration.

Skilled or unskilled drivers.


6.4. Brake – Sub systems

Energy source (muscular effort vacuum boost/power braking/surge brakes / spring brakes).

Modulation System (to control brake force).

Transmission systems (brake lines/tubes, brake hoses (flexible tube), rods /livers/cams/cables

etc. Foundation brakes.

6.4.1 System Vehicle parameters required for brake system design

Laden and unladen vehicle mass

Static weight distribution when laden and unladen

Wheelbase

Height of center of gravity when laden and unladen

Maximum vehicle speed

Tyre and rim size

Vehicle function

6.4.2 Braking standards Brake System Components & Configurations

Pedal assembly

Brake booster to reduce manual pressure ,vacuum booster(uses negative pressure in

intake manifold

Master cylinder -initiates & control braking -two separate braking circuits (primary &

secondary) -2 pistons in the same cylinder - If one system has a leak , the other takes

care

Regulating valves -when load transferred to the front , braking at rear need to be

reduced


Fig 6.1: brake system design.

6.5. BRAKING SYSTEM DESIGN – The brake system was designed to the rules,

restrictions, and requirements provided by the SAE to ensure the vehicle can decelerate and

stop within a reasonable distance. The brake system was designed with a budget of 8000 rupees

and 10kg (98 N) of pressure applied by driver.

6.5.1 MASTER CYLINDER – The master cylinders play a large part in the design phase. In

order to satisfy the deceleration goal of 0.9 g the master cylinders would have to be able to

transfer the correct amount of pressure to the brake caliper pistons. The master cylinders

chosen to do so are the rear master cylinders for a Yamaha r15 disk brake. With a 0.75 in.

bore, they would provide more than enough pressure given an average 40 kg(392N ) driver

input force by a 4:1 pedal ratio(lever arm ratio for master cylinder input force). The average

10 kg driver input force was determined thru literature survey by the team and the 4:1 pedal

ratio was decided based off calculations and pedal configuration and verified by the average

driver foot size.

Fig 6.2: brake master cylinder.


6.5.2 BRAKE ROTORS – The brake rotors are a part of the system that can be optimized

to gain performance as well as limit weight. The rotors chosen for our application is Yamaha

r15 disk brake “1CKF582W0000”. Because we are using the spindles and callipers from the

disk brake kit this match the hubs and bearing carrier selected by the chassis design

requirement.

Fig 6.3: brake disc rotor.

6.5.3 BRAKE PEDAL – The brake pedal was designed to accommodate the required pedal

ratio. The minimum ratio required to generate required force to stop the vehicle is 3.4:1 with

a driver input force of 98N. In order to make the brake pedal the correct length for the average

foot size of our drivers the ratio was increased to 4:1 (8 inch pedal). This will allow us to

require even less driver input force than the minimum experimentally measured. With the

pedal ratio of 4:1 the new minimum required driver input force to stop the vehicle becomes

40kg. Not only will this help us stop quicker but this will also help prevent driver fatigue

during an endurance race. The brake pedal will be designed out of 6061-T6 aluminium to keep

weight down while still having more than enough strength.


Fig 6.3: brake pedal.


Table 6.1: list of popular mass produced brake master cylinder along with diameter and their areas.

6.5.4 Brake fluid The three main types of brake fluid now available are DOT3, DOT4 and DOT5. DOT3 and

DOT4 are glycol-based fluids, and DOT5 is silicon-based. The main difference is that DOT3

and DOT4 absorb water, while DOT5 doesn't.

One of the important characteristics of brake fluid is its boiling point. Hydraulic systems rely

on an incompressible fluid to transmit force. Liquids are generally incompressible while gases

are compressible. If the brake fluid boils (becomes a gas), it will lose most of its ability to

transmit force. This may partially or completely disable the brakes.

As a DOT3 or DOT4 brake fluid absorbs water, its boiling point decreases. It can absorb water

from the air, which is why we should avoid opening your car's brake fluid reservoir. For the

same reason, we should always keep containers of brake fluid tightly sealed. DOT5 fluid does

not absorb water. This means the boiling point will remain relatively stable, but it also means

that any water that does get into your brake system will tend to form pure water pockets, which

could cause brake corrosion.

http://auto.howstuffworks.com/auto-parts/brakes/brake-parts/brake2.htm


Two other important things about brake fluid: DOT3 and DOT4 eat paint, . Also, none of the

different types of brake fluid should be mixed. They can react badly with each other and

corrode your brake system.

Table 6.2: brake system assembly parts along with cost.


6.6. Kinematics of braking

Graph 6.1: deceleration vs time graph.

Graph 6.2: velocity vs time graph.

Graph 6.3: displacement vs time graph.


6.6.1 Assumptions

Instantaneous change in declaration

no driver reaction time

no system response time

no deceleration rise time

no release time

6.6.2 Typical Measured Deceleration time-history

Driver reaction time t0 -t1 -driver responds & move his foot to the pedal.

Initial system response time t1 -t2 -up to start of braking force at tyre.

Deceleration rise time -time to reach peak deceleration t2 -t3.

Braking time t 3 - t 4 -till vehicle stops.

Release time t 4 - t 5 -brake release starts stopping timeto end of brake force t 0 - t 4

/t 5.

Braking time t 1 - t 4 /t 5.

Graph 6.4: declaration time behaviour for braking.

6.6.3 Retardation force

Primarily foundation braking

Rolling resistance (=0.01g).

Aerodynamic drag (proportional to at high speed) =0.03g.

Drive train drag - can contribute to the braking effort or use brake torque.

6.6.4 Load transfer during braking

• A variable brake effort ratio is required to provide ideal braking.

• Factors

Change in vehicle weight;

Change in weight distribution;


The effect of gradients (positive and negative);

Cornering, (also lateral forces);

Varying road surfaces and weather conditions;

Split friction surfaces where the coefficient of adhesion changes from front to rear.

6.6.5 Brake calculation

6.7. The Brake Pedal

The brake pedal is a simple lever. The fulcrum is at the top of the pedal arm, the input is at

the opposite end, and the output is somewhere in between. For example, a driver input force

of 98N is multiplied by a 4:1 ratio into 392N of output force. This output force becomes the

input force for the power brake unit or booster. The travel of the driver’s foot will of course

be 4 times the travel of the booster input pushrod. Pedal ratios on most vehicles today vary

between 3:1 and 5:1.

6.8. VEHICLE DYNAMICS

6.8.1 Static Axle Load Distribution

Ms/M =¥

Ms = static rear axle load (kg)

M=total vehicle mass (kg)

¥= static axle load distribution

Taking maximum total vehicle mass 140 kg

60%of total weight as static rear axle loads 84kg

Static axel load distribution is =.6

6.8.2 Relative Centre of Gravity Height

H/Wb = X

h = vertical distance from C to G to ground on the level (m)

Wb = wheelbase (m)

X= relative center of gravity height

Vertical distance from c of g to ground is 10 inch = .254 m


Wheelbase is 1150 mm= 1.15 m

Therefore, relative center of gravity height = .22

6.8.3 Dynamic Axle Loads (Two Axle Vehicles Only)

The changes in axle loads during braking bear no relationship to which axles are braked.

They only depend on the static laden conditions and the deceleration.

((1 - ¥) + (X.a)).M = Mfdyn

a = deceleration (g units)

M = total vehicle mass (kg)

Mfdyn = dynamic front axle load (kg)

Dynamic rear axle load =83.72 kg

6.8.3 STOPPING THE VEHICLE

Braking Force

The total braking force required can simply be calculated using Newton’s Second Law

M=140 kg

A= .9 g

G=9.81m/sec2

Total braking force =1236.06 N


6.8.4 Wheel Lock

The braking force can only be generated if the wheel does not lock because the friction of

a sliding wheel is much lower than a rotating one. The maximum braking force possible

on any particular axle before wheel lock is given by:

Dynamic axle mass =83.72kg

G=9.81m/s2

Coefficient of friction b/w road and tyre= 0.7

Total possible braking force on axel =574.90N

6.8.5 Brake Torque

Braking force for the axel= 574.90N

Static laden radius of tyre 10 inch =.254m

Speed ratio =1

Brake torque = 146.02 Nm

6.8.6 FOUNDATION BRAKE

Disc Effective Radius

The effective radius (torque radius) of a brake disc is the centre of the brake pads by area.

For dry discs it is assumed to be:


D=.220m

D=.170m

Effective radius =.09m

6.8.7 Clamp Load

T=146.02Nm

Re=.09m

Coefficient of friction =.40

N=2

Clamp load = 2028.05N

8.8 GENERATING BRAKING

System Pressure

Pressure is a function of the required clamp load and the piston area. Remember on an

opposed piston disc brake it’s only the area on one side of the disc.

C= 2028N

A=.4418

P=4590.3 MPa


6.8.9 Calculating Master Cylinder Line Pressure

Pressure = (Leg force on the pedal) x (Pedal Ratio) divided by (Master Cylinder Piston Area).

Pressure =484 psi

Stopping distance

Work done =force x distance

K.E= ½ x mass x velocity2

Mass of car 140 kg

Velocity =11.11m/s

Braking force= 2028N

K.E= ½ x 140x11.11x 11.11

=8640.27j

W.D=K.E

8640=2028 x stopping distance

S.D= 4.26m.

Braking efficiency =brake is 100% efficient. Producing deceleration equal to 9.81m/s2.

Considering reaction time of 0.25 sec.

Thinking distance =.25x 11.11=2.77m

Deceleration = 1x 9.81=-9.81m/s2

Stopping distance = 4.26+2.77

= 7.03mts


Fig 6.5: Thermal

Maximum heat flux is 3.7e-13 W/mm2

Minimum heat flux is 8.1e-16 W/mm2


Fig 6.6: Stress

Maximum Stress is 0.26 MPa

Fig 6.7: Strain

Maximum strain is 1.32e-6

Fig 6.8: Total Deformation

Maximum Deformation is 1.54e-5 mm


7. FRAME:

7.1. Introduction

Here is a discussion about the design of the Frame. Frame is one of the most important part

of a vehicle as it is responsible to provide the driver safety and each and every component of

the vehicle will be mounted on it. Even it responsible for weight distribution hence stability of

the vehicle. The chassis design is crucial to the success of the project because if the chassis

fails, that puts the Baja and the driver at tremendous risk.

7.2. Objectives:

Our objectives in designing an Eco Kart frame are:

Providing ultimate level of safety for absorbing all the impact and protect the driver

Be aesthetically pleasing

Lightweight

Easy to sit and leave the seat

Simple Design for Easy Manufacture

7.3. Design of frame:

For designing Eco Kart frame some parameters are considered. They are:

7.3.1. Safety:

Safety is the top priority in the design of the frame. Most of the SAE rules pertain to safety.

The selected material has been chosen is strong enough to sustain all types of load which are

supposed be applied over it. And the diameter and thickness of primary and secondary

members must be enough with some factor of safety.

Triangulation has been done to the places where the loads are more which are proved to more

efficient than rectangular members.

Shock absorbing bumper is used, where spring is used which increases comfort while small

impact.

7.3.2. Ergonomics and Comfort:

For designing and deciding the dimension we first considered the space needed by the driver

to seat comfortably. To improve ergonomics, driver is provided with more legroom. And we

have taken care that driver of 5’6” height to 6’2” can be seated without compromising with

comfort.


7.3.3. Dimensions:

As proclaimed before dimensions are decided mainly considering two things

Drivers’ comfortable seating position

Minimum wheel base possible

For that we first let the drivers of

different height, be seated in their

comfortable position and took

measurements.

Fig 7.1: Seating position & dimension measurement

And further more keep the space minimum just to keep the motor and CVT assembly behind

the driver seat. Here’s a diagram showing all dimensions

` Fig 7.2: Dimension of frame design (Top view) [all dimensions are in mm]


Fig 7.3: Dimension of frame design (Side view) [all dimensions are in mm]

7.3.4. Material Selection:

Material selection impacts both the weight of the frame, its rigidity, and its safety.

Vehicle is small kart of less weight, with less speed of 40 kmph, and supposed to run on smooth

road, considering this we have set our benchmark maximum strength will not be more than

SAE BAJA frame. The rules specify the bending stiffness as no less than that of a 1in diameter

steel tube made out of AISI 1018 alloy with a 0.12 in wall thickness.

There are lots of materials which are used now a days. Steel is mostly used everywhere,

following it aluminum and even carbon fibers.

Carbon fiber does not come in our budget, and also not available here easily, so we firstly

rejected it.

And aluminum has density 3times less than that of steel, hence increasing strength to weight

ratio a lot, really a tempting one. But it costs more, and comes with unnecessary complication

for fabrication. We need to take special care for attaching each and every mere thing.

Where working with steel is very easier compared to all other material. On steel we can mount

each part easily by simple welding processes. It is the most promising one. Price is also less,

and easily available. And a little heavier chassis may show better results in weight distribution.

So we decided to use steel for frame. But in some other parts, where it is convenience we will

use aluminum also.

But there are a few thousands types of steel available. We faced it very difficult for choosing

among them. We need to find best strength to weight ratio and also other favorable properties

like ease of fabrication.


Here is comparison of the properties of some materials

Table 7.1: Properties of Materials

From these materials list we have chosen AISI 1080 (annealed) to make frame. It is available

in near to our locality. Which has good strength to weight ratio.

AISI 1080 is a Standard grade Carbon Steel. It is composed of (in weight percentage) 0.75-

0.88% Carbon (C), 0.60-0.90% Manganese (Mn), 0.04 %( max) Phosphorus (P), 0.05 %( max)

Sulfur (S), and the base metal Iron (Fe). Other designations of AISI 1080 carbon steel include

UNS G10800 and AISI 1080.

Typical chemical composition of AISI 1080

C: 0.60-0.90

Si: 0.60

Mn: 0.45/0.70

S: 0.05

P: 0.04

Ni: 1.30/1.70

Properties:

Density: 7850 kg/m3

Elastic modulus: 205 GPa

Poisson’s ratio: 0.285

Yield strength: 390 MPa

Tensile strength: 650 MPa

Steel Yield strength(MPa) Tensile strength(MPa) Density (kg/m3)

1018 365 435 7870

1020 295 395 7870

1030 340 460 7870

1080 390 635 7870

4130 460 560 7850

4340 470 740 7850


From table 1 we can chose best suited material for our design. But, there are so many

combination of standard external diameter with wall thickness available.

Table 7.2: Tubes of available sizes.

We need to choose the best in our way.

Bending Stiffness (M) = EI

Where,

E: Elastic modulus [205000MPa]

I: Second moment of inertia (mm4)

The best way to increase I while decreasing area is to increase outer diameter and decrease

wall thickness. The minimum wall thickness we are recommending to be 1.6mm as anything

less than that is very difficult to weld.

And to keep the weight minimum we need take minimum outer diameter, which just can bear

the load on it in all driving condition.

Choosing correct outer dia was like a iteration. First we choose 25.4mm, then found it not

satisfactory and decided to use 31.8. Then after analysis we found 28.6mm tube also holds

good and we finalized it. Only one tube on which most of the drivers weight directly affects

we are providing wall thickness of 2mm.


M = 205000 × 𝜋

64 × (28.64 – (28.6 – 3.2)4)

= 254417772

I = 12410.62 mm4

Bending strength, B =

Where, Sy = 390 MPa

C = distance of extreme fiber from neutral axis = 14.3mm

B = 338471 Nmm

= 338 Nm

It is enough because it achieved even the BAJA rule which was our bench mark for highest

strength.

7.3.5. Structural Considerations:

Using a bend instead of welding the tubes produces a sturdier frame. Tubes may bended as

much of the frame as possible.

Circles or semicircles are good shapes to work with since they lack corners. Corners tend to

act as stress risers. Welding involves joining two or more metal parts together. When this is

done, it creates a corner or an edge, where stress concentrations can occur.

Furthermore, bending one is not joining two separate bodies so the end result is tougher as

the weld is something that is more likely to fail. Bending instead of welding, the loads are

distributed more evenly improving the rigidity of the frame.

In areas of the frame where welds are needed, there three tubes may be joined and that join

together to create a triangle. Triangle is a good shape from a structural standpoint as it is the

next shape with the fewest corners. A triangle less likely to twist than a rectangle or other

polygon. Another advantage of the triangle is that is can be slanted and this increases the

likeliness of something to deflect off of it when it is hit.


7.3.6. Accessibility:

As a go kart is not having body works much, and all the parts are open, all the component are

quite easily accessible by default.

Still for the driver comfortable work all the parts are spaced such a way that from his seating

position he can extend his arms to the all components he may need to.

7.3.7. Manufacturability:

Simplicity in the design is important in order to make it easier to manufacture. However, due

to a combination of the material choice and bend usage instead of welds in certain locations,

the overall manufacturability is negatively impacted. The steel has a tendency to wrinkle when

bending because of its high stiffness and the relative thinness of the walls of the tubes. To

improve manufacturability, only the tubes having less relative thickness may be blended.

But overall it is easier than aluminum and other materials.

Welding: Tungsten inert gas, or TIG welding is most time consuming type of welding

process. But it is too costly and not available everywhere. And for critical joints it is difficult

to do.

So for us metal inert gas, or MIG welding will be helpful. And it is cheaper and easier than

TIG welding. This process is very precise and suitable for ECO KART frame as it creates no

spatter or slag and is the cleaner type of welding process because it requires no clean up.

However, it requires a lot of pre-weld prepping and meticulous cleaning of the material.

7.3.8. Body & Floor pan:

Modern racecar bodies are usually made out of the lightest materials with only enough

strength to accomplish the task of holding their shape for aerodynamic performance during the

race. The best composite material would be carbon fiber. However, carbon fiber material is

not a feasible idea because of its price and unavailability.

We need body works just to make the kart look good and for a little aero dynamic effect. It

should be little strong just to be able to withstand the aero dynamic resistances. We are fixing

foam sheet with fasteners and glue as body of our vehicle

The bottom floor pan will be made from a sheet of aluminum having thickness of 0.035”,

for allowing the driver to keep his feet comfortably on the frame.


7.4. Model & Analysis:

We made several models of our chassis using Creo Parametric so that to check how the kart

does looks. It was also an iterative process we made so many models. Some of them are shown

below:

7.4.1 Design Alternatives:

Fig 7.4: Iteration 1



Design are progressively superior to the previous in terms of strength to weight ratio.


To analyze the strength, factor of safety ANSYS is employed. Taking proper loads on each

members with appropriate G forces the analysis for

1. Static load

Fig 7.7: Stress

Maximum stress is 37.96MPa

Fig 7.8: Maximum Deformation

Maximum deformation is 0.64 mm


Fig 7.9: Factor of Safety

Minimum factor of safety is 2.27

2. Frontal Impact

Fig 7.10: forces acting while an impact

Applying 4g force impact analysis is done. The results are shown below:


Fig 7.11: Stress

The maximum stress is 33.434 MPa

Fig 7.12: Total deformation

Maximum deformation is 0.557 mm


Fig 7.13: Factor of safety

The minimum Factor safety is 2.57.


8. Assembly & Mounting:

All the other components are spaced on with so many things in mind like, because it has

influence on ergonomics, aesthetics, weight distribution and accessibility.

We decided the proper space for the components and made another small frame according to

the dimensions of the components and provide proper mounts for them.

We trying to make them to do multiple task, like instead of making separate mountings for

each parts we are making them the sub frame to hold more than one components which are

comfortable with each other. For eg. On the side cage made for battery we are attaching brake

master cylinder. This idea helped us to decreasing weight a lot and complexity and cost as

well.

8.1. Rods & Fasteners: For assembly we have used some materials and fasteners, here’s

a list of some most used things.

1. Shape rod for making cage for battery, stand for motor, CVT, and other

components

2. Shape rod for making sub frame on main frame to keep and mount all

other components

3. Nuts & bolts:

8.2. Mounts:

8.2.1. Steering system mount:

On the high lightened portion steering column will

be place through some bushes, so that it can be turned

easily.


8.2.2. Front stub axle mount:

C clamp made of iron plate of 5 mm thickness is used. Iron

can be easily joined to the chassis by means of any welding

processes, that’s why in spite of heavy weight we are using it.

8.2.3. Electrical system:

Display for showing battery status (with kill switch) is

mounted on the stand for steering column,on a L shape rod. It

will be simply attached with the help of tape and adhessives so

that it can be easily removed when needed.

The figure shows the cage made of L-shape rod for battery

and the small box for main switch, which is spaced on the left

side of the driver seat.

Motor controller and Battery management system is placed

on a tray on the left side of the driver seat.


8.2.4. Seat:

The back portion of the seat is kept on the tube which goes

across the frame, which takes most of the driver’s weight.

On those cross tubes there are to L-shape small stand which

supports the seat from the front. And seat is fitted on those

with suitable nuts and bolts.

8.2.5. Fire extinguisher:

Fire extinguisher is placed on the right of the driver

seat. On the joint of tubes of main frame creates a tri arm

shape on those three arms we made stand with L-shape

rods on which fire extinguisher can easily seat. This idea

reduces complexity and weight. And driver can easily

remove it from its place and use it in minimum possible

time.

8.2.6. Power unit:

Behind the driver seat stand are made for motor and cvt. The L-

shape rods are used. On which motor will be place by means of

screws.

The power shaft is mounted on the

frame by four bearings and bearing

holders on it. The bearing holder


gives the power shaft required height, and holds it strongly to the chassis.

8.2.7. Braking system:

Brake master cylinder is

attached on a rod of the cage

for battery. In this way we are

making the mounts to

perform multifunction. It

reduces weight and implied

costs also.

8.2.8. Front and rear bumper:

On the front and rear of the frame tubes

are kept open through which the front and

rear bumper will be connected, which is

removable, so if any damage appears on

bumper it is easily removed, repaired

then again fitted.


8.3. Innovation in bumper design:

We have done an innovation to our front and rear bumpers. It is mostly based on safety of

driver as well as its comfort level also enhanced at time of impact. We have employed shock

absorbing spring between the main frame and bumper, which absorbs the most of the shocks

before it gets transmitted through metal tube.

Fig 8.1: Front Bumper


8.4. Weight distribution: Weight distribution is a very important issue for making an efficient go kart. Our target

is to achieve 43-57 front to rear and 50-50 left-right weight distribution. Which was roughly

achieved.

Fig 8.2: Distances of the weights from the front axle [all dimensions are in mm]

The figure shows the distances of considerable weights. From the values and distances of the

weights the distance of the center of mass from the front axle was found. From that we got a

ratio of weights acting front and rear axle.

The result is

Front: rear = 40.0625: 59.9375

Left: Right = 49.77: 50.23

Which is not 100% perfect but the results are acceptable. There should not be any problem

with it.


9. REFERENCES

1. Multibody Systems Approach to Vehicle Dynamics –by Michael Blundell & Damian

Harty

2. An Introduction to Modern Vehicle Design - Edited by Julian Happian-Smith

3. (IJISME) “An Innovative Energy Efficient Automobile Design” ISSN: 2319-6386,

Volume-2 Issue-10, September 2014

4. (IJAET) “DESIGN AND ANALYSIS OF HYBRID GO-KART” E-ISSN 0976-3945

5. “SHELL ECO-MARATHON Final Report”-Florida International University;

February 20, 2012

6. (IJITEE) “Optimization of Chassis of an All-Terrain Vehicle” ISSN: 2278-3075,

Volume-2, Issue-2, January 2013

7. 2013-2014 WPI SAE Baja Vehicle; Date: April 10, 2014

8. (IJERA) “Design And Fabrication Of Environment Friendly Kart”; ISSN: 2248-9622

13th-14th March 2014

9. DESIGN REPORT OF THE ECOKART VEHICLE - BY HAMMER HEADS

TEAM

10. Ackermann steering geometry-Wikipedia, the free encyclopedia

11. The S-90 Go-Kart; Alternative Design Report 1-By James Paolino, Alexander

Jadczak, Eric Leknes, and Tarek Tantawy; Sean Stenglein. NSF Projects; Ashford,

CT. 860-429-1059

12. Union College SAE Baja Vehicle Design Report- by Matthew Beenen, Jon Wilson

and Ned Lincoln



Documents

SAE-ECOKART Final Report