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