DESIGN OF A POWER TRANSMISSION 
SYSTEM OF A PEDAL CAR 
by 
A.Edirisinghe 
Supervised by 
Dr. M.A.R.V.Fernando 
LIBRARY 
UNIVERSITY OF MORATuVJA. SRI LAWK A 
MORATUWA 
This thesis was submitted to the Department of Mechanical Engineering of the University of 
Moratuwa in partial fulfilment of the requirements for the Degree of Master of Engineering 
in Manufacturing Systems Engineering 
Department of Mechanical Engineering 
University of Moratuwa 
Sri Lanka 
July 2006 
University of Moratuwa 
87885 
8 7 8 8 5 
DECLARATION 
This Dissertation paper contains no material which has been accepted for the award of any 
other degree or diploma in any University or equivalent institution in Sri Lanka or abroad, and 
that to the best of my knowledge and belief, contains no material previously published or 
written by any other person, except where due reference is made in the text of this 
Dissertation. 
I carried out the work described in this Dissertation under the supervision of 
Dr. M.A.R.V. FERNANADO 
Signature Date : 2 2 n 0 July.2006 
Name of Student : A.Edirisinghe 
Registration No : 02/ 9630 
Signature Date 
Name of Supervisor: Dr. M.A.R.V. FERNANDO 
ACKNOWLEDGEMENT 
It is with deep gratitude I acknowledge the generous assistance, kind and valuable guidance of 
my Supervisor Dr. M.A.R.V.Fernando and Dr. G.K. Watugala of the Department of 
Mechanical Engineering University of Moratuwa in completing this study successfully. 
I wish to thank Dr.A.G.T. Sugathapala, Head of the Mechanical Engineering Department, 
Former Heads, Dr. R.A.Athalage and Dr. S.R.Thithagala, Course Coordinators, Dr. 
U.Kahangamage and Dr.P.A.B.A.R.Perera, Lecturer H.KG.Punchihewa and the academic 
staff of the University of Moratuwa for their valuable advice and excellent guidance offered 
throughout this Research Study and making arrangements to demonstrate First Embodiment 
of our pedal car in the Exhibition held at Bandaranayake Memorial International Conference 
Hall, and also wish to extend my thanks to visiting Lecturers and all the university Lecturers 
who enlightened throughout the Master of Engineering Course. 
I also wish to extend my sincere thanks to all other staff of the University of Moratuwa for 
their contribution and friendly support in the course of the study. 
Further, I wish to extend my warm gratitude and thanks to the Factory Engineer Mr. W. 
Galappaththi of the Government Factory for allowing me to use the resources for fabrication 
of First Embodiment of the Pedal car and, Former Factory Engineer and the Former Secretary 
to the Ministry of Cooperative Development, Eng. .K Mahanandan who generously gave me 
the opportunity to practice and develop my skills in par with my studies, and I shall not forget 
to appreciate the staff of the Government Factory, devoting their valuable time to help, 
fabricating the first embodiment, specially, the Supervisors of the Machine shop Mr. 
U.S.K.Pothupitiyage Mr. K.A.S. Prematilake and Motor Mechanic, Mr. H.A.S.K.Perera. 
I wish to appreciate my colleagues Mr. M.S.M. Zuhair and Mr. C.Molligoda who immensely 
coordinated and joined in fabrication of first embodiment, sharing information, sharing 
expenses of fabrication and completion within seven days. I further extend my sincere thanks 
iii 
to Mr .M.S.M.Zuhair and his staff of Test Com (Pvt.) Ltd of Dehiwala, who dedicated in 
doing finishing touches of the first embodiment beautifully. 
I specially thank my wife for encouraging me towards successful completion of this 
research study while my little son and daughter who tolerated and sacrificed their hour of 
need. 
Last but not the least I am grateful to my friends and colleagues who lavishly shared their 
knowledge and expertise and for all others who helped me in their own special way without 
which this would not have been a success. 
iv 
Abstract 
Transportation has become a major socio-economic and environmental problem in urban 
environments today. Escalation of oil prices, environmental pollution, unsafe conditions, 
unbalanced designs of bicycles, motorcycles, and three wheelers and complex lifestyle are 
some of those significant contributing factors to it. Ergonomically designed Human 
Powered transport is one of the feasible solutions for urban requirements. Ergonomics deals 
with human comfort in any work situation in order to operate it efficiently and effectively. 
Concept of pedal car came into being in order to eliminate discomfort and unsafe conditions 
due to heat, dust, rain, unbalanced designs, uncovered body, and fatigue due to uneasy 
postures. In addition to the above it provides cheap transport and recreational facility, physical 
exercise, while providing additional value for the rider to iron out complex health hazards. 
Design of Power transmission system integrates with Engineering aspects, strength, rigidity, 
stability and ergonomics aspects. One of the major innovative steps taken in fabrication of 
first embodiment of the pedal car is to eliminate long chains by introducing pedal linkage with 
a shorter chain. First embodiment incorporates positive achievements such as; ergonomically 
designed compact long wheel base and seat, shorter chain, standard parts, small wheel sizes, 
affordable price, environmentally friendly, fashionable appearance, Easy manufacturability 
and maintainability of Driving Mechanism, and physical exercise to the rider. Over weight of 
frame and wheel assembly deprived acceleration in gradient at 30° to 8Km/h and 15-18Km/h 
in level roads. Reduction of weight of the first embodiment by re-design and re-selection of 
parts with lighter hood cover with additional power supply to the system also required to 
overcome the above problem. One of the major limitations of this study is maximum human 
power in put. Further study on maximum power application in relation to pedal height, seat 
angle, foot position and crank length is also important for further improvements. 
Table of Contents 
Title 
Declaration 
Acknowledgement 
Abstract 
List of contents 
List of illustrations 
List of tables 
Chapter I - Introduction 
1.1 Overview 
1.2 Outline 
1.3 Limitations 
1.3.1. Length of the First Embodiment and 
Recumbent type 
1.3.2. Seat Adjustability 
1.3.3. Speeds in Level Roads and Gradient 
1.4. Literature Survey 
1.5. Conceptual Frame work 
1.6. Methodology 
1.7. Background 
1.7.1. Factors that interrelated to 
Transmission Efficiency 
1.8. Possible Solutions 
Chapter 2 - Literature R e v i e w 
2.1. Introduction 
2.2. Literature Survey 
2.2.1. Propulsion and Transmission Efficiency 
2.2.2. Power Required for Propulsion 
vi 
2.2.2.1. Resistances 22-23 
2.2.2.1.1 Rolling Resistance 23-24 
2.2.2.1.2. Frictional Resistance 25 
2.2.2.1.3 Rolling Resistance 25 
2.2.2.1.4. Gradient Resistance 27 
2.2.2.1.5. Air Resistance 27 
2.2.2.1.6. Tractive Resistance (Axle) 28 
2.2.2.2. Power required or demand power 28 
2.2.3 Power Available 29-30 
2.2.4. Gradient Performance 30 
2.2.5. Tilt resistance of tricycles 31-33 
2.2.6. Types of Belt Drives 34-40 
2.2.7. Chain Drives 40-42 
2.2.7.1. Chain classified 43 
2.2.7.2. Chain Selection Factors 44 
2.2.7.3. Basic Structure of Power 
Transmission Chain 44-45 
2.2.7.4. Roller chains 45 
2.2.7.5. Bushing chains 46 
2.2.7.6. Silent Chains 46 
2.2.7.7 Type of Sprocket 47 
2.2.7.8. Kinematics of Chain Drive 48 
2.2.7.9. Angular velocity ratio 49 
2.2.7.10. Mean velocity ratio and 
Length of the chain 49 
2.2.7.11 Relationship between Pitch 
and Pitch circle diameter 50-51 
2.2.7.12. Power transmitted by the chain 51 
2.2.7.13. Impact loading 51-52 
] 
2.2.7.14. Principal Parameters of 
Chain Drives 52-54 
2.2.7.15. Distance between the sprocket 
axel and the and the chain length 54 
2.2.7.16. Advantages and Disadvantages 
of Chain for Power Transmission 55-56 
Chapter 3 - Governing Equations 57 
3.1 Introduction 57 
3.2 Governing Equations 57 
3.2.1. Motive Force 57 
3.2.2 Frictional Resistance 58 
3.2.3 Rolling Resistance 58 
3.2.4. Gradient Resistance 58 
3.2.5 Air Resistance 59 
3.2.6 Tractive Resistance (Axle) 59-60 
3.2.7. Power required or demand 
power is given by 60 
3.2.8. Power transmitted by the chain 60 
Chapter 4 - Methodology 61 
4.1 Introduction 61 
4.2 Conceptual Frame Work 61-62 
4.2.1 Use Need 62 
4.2.2 Engineers Perspectives 62 
4.2.3 Identifying Alternatives 63 
4.2.3.1 Recumbent Positions 64-65 
4.2.3.2 Wheel Sizes 65-66 
4.2.3.3 Ergonomics- Which configuration 
will work best? 66 
viii 
4.2.3.4 Types of recumbent steering 67 
4.2.3.5 Driving Mechanism 67 
4.2.4. Problems 68 
4.2.4.1 Recumbent Positions 68 
4.2.4.2 Wheel Sizes 69 
4.2.4.3 Ergonomics- Which configuration 
will work best? 70 
4.2.4.4 Types of recumbent 
steering 70 
4.2.4.5 Driving Mechanism 70 
4.2.5. Sub Problems 71 
4.2.5.1 Recumbent Position 71 
"\ 4.2.5.2 Driving Mechanism 72-74 
Chapter 5 - Construction o f the First Embodiment 75 
5.1. Introduction 75 
5.2. Frame Construction 76 
5.3 Rear Wheel and Shock Absorbers 76-77 
5.4 Steering ,Front Wheels Suspension and Brake 77 
5.5 Fixing Power Transmission System 78-79 
5.6 List of Materials, Parts used and 
Construction and Manufacturing Cost 84-85 
5.7. Problems Encountered in Fabrication 
and Solutions 86 
ix 
•4 
Chapter 6 - Performances of the First Embodiment and 
Related Issues 87 
6.1 Introduction 87 
6.2 Problems Encountered in Fabrication 87-88 
6.3. Performance of the First Embodiment 88 
6.3.1 Speeds in level Roads and Gradients 88 
6.3.2 Recumbent Position and 
Tilting Resistance 88-89 
6.3.3 Strength, Rigidity and Ergonomic 
Considerations 89 
6.3.4 Power Transmission System 89 
6.3.4.1 Crank Length and Power 
Input by the Rider 90 
6.3.4.2 Pedal Mounting 90 
6.3.4.3 Chain Drive 91 
Chapter 7 - Calculations 92 
7.1 Introduction 92 
7.2. Calculations of Power Requirements 92-93 
7.2.1 Calculation of Power Required for 
Propulsion in Level Roads 93 
7.2.1.1. Rolling Resistance 93 
7.2.1.2. Air Resistance 93 
7.2.1.3. Tractive Resistance 94 
7.2.1.4. Power required or 
power demand 94 
7.2.1.5. Power Available at 
Road Wheels 94 
7.2.1.6. Calculation of Power Required 
for Propulsion in level roads 
whenm=113Kg 95 
7.2,1.7. Power Required at road 
Wheels at different speeds 
in Level Roads for 
Acceleration 96-97 
7.2.2. Calculation of Power Required for 
Propulsion in gradients 97-98 
7.3. Discussion 100 
Chapter 8 - Conclusion 101 
8.1 General Overview 101 
8.2 Achievements and Positive Aspects 101 
8.2.1 Configuration of the first Embodiment 
(CLWB) and Ergonomically 
Designed Seat 102 
8.2.2. Stability while Riding 102 
8.2.3. Pedalling Efficiency 102 
8.2.4. Easy Manufacturability and 103 
Maintainability of Driving Mechanism 
8.2.5. Brake and Steering System 103 
8.2.6. Environmentally friendly, Fashionable 
Appearance and Inherent 
Values in Pedalling 103 
8.2.7 Affordable price 103 
8.3. Problems encountered and 
Limitations of the Study 104-105 
8.4. Recommendations 106-108 
8.5 Further Studies 108 
8.5.1 Research on application of Optimum 108-109 
Human Power against pedal height 
for Compact Long Wheel Base 
Recumbent in Sri Lanka 
% • • • 
References (Bibliography) 
Appendices A Eras of Invention of Automobile 
First patented Benz automobile of 1885 -
B Velomobile- Recent development -
C Calculation of power required for 
Acceleration in Gradients when total 
Mass of the First embodiment is lOOKg 
D Power required for acceleration in gradients 
at different speeds when M=100Kg. 
E Calculation of power required for 
Acceleration in level roads when total 
Mass of the First embodiment is lOOKg 
F Power required for acceleration in gradients 
at different speeds when M=100Kg. 
G Body shape recommended for the pedal car 
xii 
List of Illustrations 
(Page 1 of 2) 
Page# 
Figure 1: Rowing Bikes 4 
Figure 2.1: Belt Drive with two pulleys 37 
Figure 2.2: Cross section of the belt drives 37 
Figure 2.3: Basic structure of a power transmission chain 44 
Figure 2.4: Types of sprockets 47 
Figure 4.1: Types of recumbent 65 
Figure 4.2: Configuration of Compact wheel base recumbent 68 
Figure 4.3: Comparison of Delta and Tadpole layouts 69 
Figure 5.1: Model of the first Embodiment 75 
Figure 5.2: Configuration of the Frame of First Embodiment 76 
Figure 5.3: Front suspension and steering assembly to the frame 76 
Figure 5.4: Part of rear wheel assembly cut from a bicycle 76 
Figure 5.5: Assembly of front suspension to the frame 76 
Figure 5.6: Rear wheel assembly to the frame 77 
Figure 5.7: Front wheel assembly to the frame 77 
Figure 5.8: Front wheel assembly to the frame with pedal mounting 77 
Figure 5.9: Power Transmission Mechanism 77 
Figure 5.10: Front wheel racers and trust bearings 78 
Figure 5.11: Parts of hub brake 78 
Figure 5.12: Pedal Mechanism 78 
Figure 5.13: Parts of front wheel assembly 78 
Figure 5.14: Turned out parts of brake and steering assembly 78 
List of Illustrations 
4 
Page# 
Figure 5.15: Seat and steering assembly 79 
Figure 5.16: Side Elevation of the first embodiment 80 
Figure 5.17: Plan View of the First Embodiment 80 
Figure 5.18 Final Design of the first embodiment 81 
Figure 5.19: Three dimensional view of the First embodiment 82 
Figure5.20: Finished product 82 
Figure5.21: Configuration Diagram of Power Transmission System 83 
Figure 7.1: Power required at road wheels at different speeds in level roads 97 
Figure 7.2 : Power Required at different speeds in Gradients 100 
Exhibit 2.1 : Power available at the road wheels verses vehicle speed in top gear 29 
Exhibit 2.2 : Effects on traction against speed ratio 30 
Exhibit 2.3 : Traveling around a curve with single wheel in front 31 
Exhibit 2.4 : Traveling around a curve with single wheel in front 32 
Exhibit 2.5: Tadpole Configuration 32 
Exhibit 2.6 : Kinematics of chain drives (Chain drive with sprockets wheels) 48 
Exhibit 2.7 : Elastration of chain and sprocket motion 49 
Exhibit 2.8 : Chain running round a sprocket 50 
Exhibit 4.1: Delta Layout of a tricycle 63 
Exhibit 4.2: A Trice X2R back-to-back recumbent tricycle 63 
Exhibit 4.3: Proposed layout of Driving Mechanism 73 
xiv 
(Page 2 of 2) 
List of Tables 
Page# 
Table 1.1: Factors that interrelated to Transmission Efficiency 18 
Table 2.1: Rolling Resistance for various surfaces 24 
Table 2.2: Types of belt drives and applications 35 
Table 2.3: Types of belt drives and applications 36 
Table 2.4 Types of chains and applications 43 
Table 2.5 Speed of rotation of different types of chains in relation to pitch 53 
Table 2.6 Comparison of Chain, belts, and Gears 56 
Table 4.1: Recumbent types 64 
Table 4.2: Comparison of Tadpole and Delta models 72 
Table 4.3: Comparison of relationship between input power exerted by the rider 
and Crank Length of bicycles 74 
Table 5.1: List of parts used for Fabrication 79 
Table 5.2: List of Materials, Parts used for Construction and 
Cost of Manufacturing 84-85 
Table 7.1 Power Required for Propulsion in Level Roads When M=l 13Kg 95 
Table 7.2 Power Required at road Wheels at Different Speeds in Level 
Roads 96 
Table 7.3 Power Required at different speeds in Gradients 98 
Table7.4 Power Required at road Wheels at Different Speeds in 
Gradients when mass reduced to 1 OOKg 99 
« 
xv