Recumbent Tricycle for Disabled User - Research Paper Example

RECUMBENT TRICYCLE FOR DISABLED USER A Dissertation Presented to the Faculty of the Department of Mechanical Engineering College of Engineering Write Your University In Partial Fulfilment Of the Requirements for the Degree Bachelor of Science in Mechanical Engineering Submitted By: Write Your Name Please ACKNOWLEDGMENT The researcher wishes to convey his profound gratitude and sincerest appreciation to those who have extended much effort and assistance contributory to the success of the dissertation. His deepest indebtedness goes particularly to the following: Almighty God, for giving him strength, wisdom, and vision to finish his study; His Supervisor, for his guidance and suggestions to improve the research work; His family, who reassured, inspired, and supported him morally, and financially; His colleague and friends, for their words of encouragement; All others who helped the researcher make this dissertation possible. ABCTRACT This dissertation aims to discuss the development of a recumbent tricycle for disable user (one-handed user). It will specifically endeavour to examine the design and manufacture of the suspension system of the recumbent tricycle especially designed to be driven single handed. Full suspension is integrated in the proposed recumbent tricycle for single - handed users; this means that it has front and rear suspension system. The front suspension will simply make use of the front fork suspension common in other bicycles and tricycles. The rear suspension however, has been designed particularly to provide additional comfort and safety for a disabled user. It will make use of shocks and external springs together with movable joints and axles. TABLE OF CONTENTS Title Page ''''''''''''''''''''''''''''''.... i Acknowledgment ''''''''''''...''''''''''''''' ii Abstract '''''''''''''''''''''''''''''''. iii Table of Contents '.......................................................................................................... iv List of Figures '''''''''''''''''''''''''...'''. v List of Tables ''''''''''''''''''''''''''''' vi INTRODUCTION CHAPTER 1. INTRODUCTION 1.1 Aim and Objective 1.2 Basic Assumptions 2. HISTORY 2.1 Tricycle 2.2 Suspension 3. PROJECT MANAGEMENT 3.1 Summary of Risks and Actions to Take 3.2 Development of Key Skills 4. BACKGROUND 4.1 Suspension System for Tricycle 4.2 Tricycle Lay-outs 5. USER 6. THEORY AND EQUATION 6.1 Spring Rate 6.2 Damping 7. MOTION MECHANICS 7.1 Front Fork Suspension 7.2 Rear Suspension 8. DEVELOPMENT AND DESIGN OF SUSPENSION BY SOLIDWORKS 9. MATERIALS FOR THE SUSPENSION SYSTEM 10. MANUFACTURING THE SUSPENSION 11. CONCLUSIONS REFERENCES LIST OF FIGURES Figure 2.1 Starley's Coventry Rotary Tricycle Figure 2.2 Humber Cripper (Griffin 1885) Figure 2.3 Leaf Springs (Courtesy of Yahoo! Images) Figure 2.4 The English longbow (Courtesy of Yahoo! Images) Figure 2.5 Helical or Coiled Springs (Courtesy of Yahoo! Images) Figure 2.6 Shock Absorber Diagram (http://www.babcox.com/editorial/tr/30158.htm) Figure 2.7 Anti-roll Bar Figure 2.8 Track Bar (Courtesy of Yahoo! Images) Figure 4.1 Fork Suspensions (Silltech Inc. 2005; Yahoo! Images). Figure 4.2 Suspension Seat Post Figure 4.3 Rear Suspension Figure 4.4 Typical Upright Tricycle (Yahoo! Images) Figure 4.5 Delta Recumbent Tricycle (Yahoo! Images) Figure 4.6 Tadpole Recumbent Tricycle (Yahoo! Images) Figure 5.1 Brakes Figure 5.2 Rear View of the Proposed Suspension System for a Single-handed Recumbent Delta Tricycle (Seen at the Back). Figure 6.1 The Force to Stretch a spring is Proportional to its Elongation: Figure 6.2 Shock Absorbers: A - Piston; B - Cylinder; C - Piston Rod; D - Oil Figure 7.1 Threaded Adjuster Cap Figure 7.2 Lock - ring Adjuster (Baker 2008) Figure 7.3 Ramp - type Preload Adjuster (Baker 2008) Figure 8.1 Shocks and Springs System Figure 8.2 Shocks and Spring System Assembly Parts Figure 10.1 Rear Suspension Assembly Figure 10.2 Rear Wheel Movements within the Suspension Frame Figure 10.3 When Rear Wheel Hits a Bump Figure 10.4 When Rear Wheel Hits a Hole LIST OF TABLES Table 1 Front Spring Selection Options Table 2 Rear Suspension Modification Options Table 3 Standard Springs CHAPTER 1 INTRODUCTION 1.1 Aim and Objective This dissertation aims to discuss the development of a recumbent tricycle for disable user (one-handed user). It will specifically endeavour to examine the design and manufacture of the suspension system of the recumbent tricycle especially designed to be driven single handed. This study will also provide answers to the following questions. 1. What are the features of the existing recumbent tricycles to be considered in the development of the proposed one-handed user recumbent tricycle' 2. What will be the features of the proposed one-handed user recumbent tricycle in terms of: a. Tricycle Lay-out b. Suspension System c. User Friendliness 3. What will be the materials used by the proposed project, particularly the suspension system' 1.2 Basic Assumptions The above questions are taken from the following assumptions. 1. The suspension system of this Recumbent Tricycle for Disabled User will be making use of parts and components readily available in the market. 2. This Recumbent Tricycle for Disabled User will be user friendly. 3. The One-handed Recumbent Tricycle will incorporate some designs and features from existing recumbent tricycles available today. CHAPTER 2 HISTORY 2.1 Tricycle Three - wheeler rides or tricycles caught the interest of many people because of the safety and merits it brought to cycling. Riding a tricycle does not require enormous skill or strenuous practice. The only thing you have to do is position yourself, step on the pedals and ride on. There are several expediencies that a tricycle can offer such as sustaining larger baggage capacity and accommodating conventional women's wear. Thus tricycle offers both convenience and comfort. A German paraplegic named Stephen Farffler constructed the first tricycle in 1680. Several improvements, enhancements and developments were made to the tricycle during the next few decades, specifically from 1789 to 1886. The first patented tricycle was the "Coventry Lever Tricycle" in 1876 (Bijker 1997, p. 56). This was driven by a lever gear with no chain. This type of three-wheeler, with a fixed axle on the two gears, presented some trouble: there was difficulty in making turns. In order to correct this problem, differential gears was introduced. James Starley's invention of the differential gear successfully corrected this. The two axles are not anymore connected, but two bevel wheels connect the two gears in the middle. Starley's invention was patented in London. (Bijker 1997, p. 56) This gave birth to the first generation tricycles such as the Starley's Coventry Rotary (See Figure 2.1) which became popular during the years from 1876 to 1884. The modern invention introduced the chain driver which is safer and faster. Figure 2.1 Starley's Coventry Rotary Tricycle The Humber Cripper, named after professional racer Robert Cripps, is a classic second generation tricycle which emerged in 1885. It is apparent in Figure 2.2 that the front wheel of the tricycle is way much smaller than the rear wheels. The front wheels typically have a diameter of about 18 to 24 inches in diameter whilst the rear wheels are around 40 inches. In 1892 one of the earliest third generation tricycles is the Starley Psycho. These types of tricycles are much like of what can be seen today. The size of both the front and rear wheels were the same, usually 28 inches in diameter. (Triporteurs 2007) Figure 2.2 Humber Cripper (Griffin 1885) Tricycles were eventually modified. One such modification was the recumbent three - wheeler ride. The Recumbent Recumbent means "laid back"; thus in a recumbent vehicle the rider is in a reclined position as the legs are extended forward from the body. The 'first illustration of a recumbent bicycle was printed in 1893 in the Fliegende Bltter ("Flying Pages"), a humour magazine from Munich' [and] the 'Fautenil Velociped, which said that the first recumbent bicycle in the world was built using balloon tires'. (Fehlau 2006, p. 5) In a recumbent, the rider is not required to sit very high thus the risk and likelihood of a fall is reduced compared when riding a bicycle. Furthermore, the rider could easily steer with one hand. Recumbent brakes are rather unique, for example a shoe brake which is astutely mounted to the rear wheel may be used. Recumbent tricycles are classified into two namely, the Delta Recumbent and the Tadpole Recumbent. The Delta Type This type of tricycle has one wheel in front and two wheels at the back. Generally delta tricycles are front wheel steer and rear wheel drive. According to David Williams (2009), "One-wheel drive delta tricycles pull to one side when accelerating and climbing which can be annoying [while] the less expensive Delta tricycles usually have over seat steering (OSS). They are typically higher, easier to get into and out of, larger, heavier, slower and less sporty. Delta tricycles are the least expensive recumbent tricycles." The Tadpole Type This type of recumbent tricycle has two front wheels that steer. This type has one rear wheel, driven by pedals, with an under seat steering (USS). This kind of recumbent tends to be lower, smaller, lighter, faster, sportier, harder to bet into and out of and more expensive than the Delta tricycles. The tadpole type is not apt for low speeds but is suited for higher speeds and long distance rides. Recumbent tricycles became popular to the public because it offers comfort and stability. The sitting or reclined position allows the driver's feet in a forward and relaxed position. It is just like you are seated in your favourite sofa in your living room watching television. Recumbent tricycles made it unnecessary for fans and enthusiasts to bring with them chairs during a tour or a trip to the beach. The expediency and safety are pronounced in the recumbent. Riding experience is rather comfortable in this type of tricycle. Unfortunately the popularity of tricycles faded during the 1900's. Most people have relied on bicycles and eventually, the tricycle industry took a plunge. This is basically due to the modernization of the bicycle components and lack of evolution in the tricycle production. Numerous companies around the world stopped manufacturing tricycles. Today however, tricycles are still used for recreation, exercise and as a commercial transportation. 2.2 Suspension In transportation, suspension system is primarily used to lessen vibration in a vehicle. It reduces the jolt of bumps and uneven pavements on the vehicle's occupants and provides the wheels better surface contact. The idea of a suspension can be traced back from the ancient Egyptians. They used wooden leaf springs, such as with a bow, in catapults. Later during the early 19th century, British horse carriages made use of springs which are either made of wood or steel. These steel springs were made of low - carbon steel and typically resembled a multiple layer of leaf springs (See Figure 2.3). Due to some application constraints, the British springs were not frequently used in the United States. Instead, the Abbot Downing Company of Concord, New Hampshire developed leather thoroughbraces which offers a swinging motion to minimize the shock in a vehicle. Figure 2.3 Leaf Springs (Courtesy of Yahoo! Images) A suspension system primarily consists of springs, shock absorbers, stabilizers and bushings. Springs Springs are elastic and stores mechanical energy. They are commonly made out of medium or high carbon steel known as hardened steel. Unlike typical springs that we can see today, ancient non - coiled springs such as the English longbow (Figure 2.4) were made of wood. It is only during the 15th century that coiled springs (Figure 2.5) appeared. Figure 2.4 The English longbow (Courtesy of Yahoo! Images) Figure 2.5 Helical or Coiled Springs (Courtesy of Yahoo! Images) Springs can be classified according to the material they are made from and the load they are designed for. Depending on the spring material, it can either be a wire/ coil spring or flat spring. With regards to load bearing, they can either be tension/ extension spring, compression spring or torsional spring. In a suspension system, the springs provide cushioning when the vehicle's wheels strike a bump or hole in the road. The placement of springs varies in every particular suspension system. Usually, springs are placed close to every wheel so that when a wheel hits a bump and pushed up, the spring is compressed. Then the spring opposes the force and recoils, shoving the wheel back down. Shock Absorbers Shock absorber is a damper that is designed to even out shock impulse. It is commonly used to help cushion vehicles on jagged road. Like springs, a shock absorber is sited at each wheel; it prevents the springs to continue vibrating. A common shock absorber is composed of a piston snugly fitted inside an oil - filled or air - filled cylinder (Look at Figure 2.6 for the Diagram of a Shock Absorber). Stabilizers A suspension has to be provided with additional precision thus stabilizers are incorporated. Stabilizers are flexible and supple. Some popular types are the anti - roll stabilizer (Figure 2.7) and track bar stabilizer (Figure 2.8). The anti - roll stabilizer is usually used to connect the two rear or two front wheels of a vehicle to prevent the vehicle's frame to lean during turns. Whilst the track bar ensures that the rear and front wheels are headed in the right direction throughout the suspension activity. Figure 2.6 Shock Absorber Diagram (http://www.babcox.com/editorial/tr/30158.htm) Figure 2.7 Anti-roll Bar Figure 2.8 Track Bar (Courtesy of Yahoo! Images) CHAPTER 3 PROJECT MANAGEMENT This chapter provides information on managing the risks and time restraints that may arise throughout the course of the study. It also presents the development of key skills involved in the improvement of the designs and reports of the dissertation. Project management is mainly centred on 'how' this project should be tackled. Who are to manage and how should it be done' What should be the proper flow of all activities' What are the anticipated problems' How should these problems be solved' How about time management' There are so many things to be taken into consideration. Problems are inevitable. Thus a clear and unobstructed view of the project at hand is a necessity. We have to look beyond the horizon - what will be the final outcome. As Heerkens (2001) state: "One of the biggest single challenges all project managers face is risk and uncertainty." Surely, there are things beyond our knowledge and control. However precautionary measure should be done before catastrophe comes. 3.1 Summary of Risks and Actions to Take Software Accessibility Location Problems Action to take if problem arises SolidWorks Not Available Online Buy Software At Authorized SolidWorks Distributors No Free Downloads Buy Software At Authorized SolidWorks Distributors 3.2 Development of Key Skills Microsoft Office Microsoft Office Word provides an indispensable typing tool for accomplishing and managing this paper. It showcases a user friendly panel and workspace, specifically Microsoft Word 2003. The Autoshape feature was used to design some of the figures and diagrams in this report. SolidWorks This 3D CAD Design software made it possible to develop 3D images of the components of the proposed project. SolidWorks provides load or forces simulation which is especially useful for the suspension system design. CHAPTER 4 BACKGROUND 4.1 Suspension System for Tricycle Tricycle suspension protects the rider and the tricycle itself from the unevenness of the road; it also provides comfort to the rider. Suspension system further 'improve both safety and efficiency by keeping one or both wheels in contact with the ground and allowing the rider's mass to move over the ground in a flatter trajectory'. (Silltech Inc. 2005) Suspension system for tricycles is somewhat similar to those that are employed in bicycles. One or a combination of the following suspension can be used. Front Suspension fork Suspension seat post Rear suspension Full suspension tricycles are those that have front and rear suspension system. To provide additional support and comfort, suspension may also be 'incorporated in the seat or saddle, and/or the hubs' (Silltech Inc. 2005). Front Suspension Fork Front suspension fork is frequently employed with a set of shock absorbers. When two wheels are in front, the suspension fork is used jointly with an anti-roll bar. Figure 4.1 shows a fork suspension and its details. Figure 4.1 Fork Suspensions (Silltech Inc. 2005; Yahoo! Images). Suspension Seat Post Some tricycles are fitted with suspension seat posts 'to take the edge off some of the bumps encountered on the trail'. Shown below (Figure 4.2) is a 'seat post with an elastomer dampener'. Other seat posts make use 'more conventional piston shocks'. (Silltech Inc. 2005) Figure 4.2 Suspension Seat Post Rear Suspension Among the three, it is more complicated to design and install a rear suspension. When the two wheels are located at the back they are joined using the anti-roll bar and used together with shock absorbers like the one shown in Figure 4.3. If the is only a single wheel, the arrangement in Figure 4.3 may be enough. Figure 4.3 Rear Suspension 4.2 Tricycle Lay-out Generally, there are three tricycle lay-out from which to choose from: Upright Delta Tadpole Upright Tricycle An upright tricycle has similarities with the common bicycle except it has two wheels at the back. It is also steered directly through a handle bar connected to the front wheel like a bicycle. In Figure 4.4 a typical upright tricycle is shown. Figure 4.4 Typical Upright Tricycle (Yahoo! Images) Recumbent Tricycle The last two lay-outs are for a recumbent tricycle; in this configuration the rider is lying down. Delta Configuration It is actually similar to an upright tricycle in terms of wheel configuration except that the seat is designed so that the rider is seated in a lying position. Driving the delta recumbent tricycle can use one or both rear wheels. The front wheel is used for steering, just like in the usual tricycle lay-out. Figure 4.5 Delta Recumbent Tricycle (Yahoo! Images) Tadpole Configuration Tadpole recumbent tricycle is designed with two steered wheels at the front and one driven wheel at the back. Figure 4.6 Tadpole Recumbent Tricycle (Yahoo! Images) In a recumbent tricycle it is needless to support your legs on the ground while not moving. But in a recumbent bike, you have to hold your legs on the ground. Whether the vehicle is in motion or not a recumbent tricycle is more relaxing compared to an upright one. Furthermore, many of the present recumbent are built to be suitable for long distance riding by the many present-day enthusiasts who favour the recumbent than other motor-power vehicles. The recumbent surpassed the difficulties in the ordinary bicycle or tricycle. "Because you can ride in the most comfortable seated position with never a need to put your feet down, a recumbent tricycle is like your favourite living room chair and the entire world is your television set. Often we ride our recumbent tricycles to the beach or somewhere to have a picnic, and we never have to bring chairs alone." (Graham & McGowan, 2008, p. 97) The disadvantage of the present recumbent is that they are more expensive, and harder to climb mountains. In climbing, the rider has to practice the feat at high pedal frequency. However some modifications and inventions by recumbent experts were done to counter this flaw. Additionally, the recumbent tricycle has eliminated second thoughts and doubts about safety; recumbent is no doubt safer for the disabled user or rider. The rider is safe in a reclined seat, and the positioning of the legs in a forward position is favorable for a comfortable and fine riding. Steering and Driving Recumbent Tricycles Delta Recumbent Tricycle Delta recumbent tricycle can be driven using one or both rear wheels whilst the front wheel is used for steering. Tadpole Recumbent Tricycle Tadpole recumbent tricycle is designed with two steered wheels at the front and one driven wheel at the back. It can be steered directly or indirectly. Indirect steering is done through a single handlebar connected with tie rods to the front wheels' stub axle structure. Direct steering on the other hand, is accomplished with two handlebars each bolted to a steering tube. The tadpole tricycle is often preferred because it has a very low center of gravity and superior aerodynamic layout. It is also light weight and more lithe. CHAPTER 5 USER Recumbent tricycles provide additional comfort for users compared to an upright tricycle. The lying position of the rider may even be varied to cater for different physical and visual preference of the user. It is also more suitable and appropriate for people with balance or limb disabilities and infirmities. This project allows the driver to sit in a laid back position, at the same time exerting less effort because his weight is not pressed downward; his weight is actually at the back not pressed on the centre of the bicycle. The driver does not sit so high and a fall is less likely to incur injury on the rider. There are some innovations on the "lying position" of the recumbent. Other manufacturers make it in between lying and sitting position, adding an angle on the seat and the pedals; thus it's not actually forward position of the legs, but with a certain angle downward. Moreover, traditional recumbent have diversities pertaining to the lying and the forward angle of the legs with respect to the pedals. But this innovation of making an angle of lying and sitting is more revolutionary. Some experimentation and study have to be made on this type, with observations and guidance from a doctor or health practitioner, to make recommendations on the health side of it. Single-Handed Controls for Recumbent Tricycles Modifications and enhancements in the recumbent tricycle so that it can be driven by a single-handed user may just seem difficult. Take for example the steering and braking mechanism, it can be made with dual brakes that can be actuated by one lever (See Figure 5.1). Figure 5.1 Brakes Suspension System Usually, the rear and front suspension of a recumbent tricycle are different. They have to be designed to offer smooth ride and superior handling features. For instance, we use the delta tricycle configuration (two rear wheels, one front wheel), the front suspension can simply make use of the front fork suspension common in other bicycles and tricycles (Look at Figure 4.1). The rear suspension however, is different. Figure 5.2 shows the proposed design of the suspension system for a delta recumbent tricycle. The detailed discussion of its mechanism will be discussed in Chapter 9. Figure 5.2 Rear View of the Proposed Suspension System for a Single-handed Recumbent Delta Tricycle (Seen at the Back). CHAPTER 6 THEORY AND EQUATION 6.1 Spring or Suspension Rate A suspension is simply a type of spring and all springs have rates. Spring rate is the measure of resistance during compression or extension. Under normal circumstances (spring is not compressed or elongated beyond the elastic limit); most springs abide by Hooke's Law. According to Hooke's Law, the 'force required to stretch or compress a spring is directly proportional to the amount of elongation or compression' (Sears, Zemansky, & Young 1987). It is given by the equation, Where is called the force constant, or the stiffness of the spring, is the displacement of the spring during deformation and is the force exerted by the spring (Sears et. al. 1987). (Look at Figure 6.1) Figure 6.1 The Force to Stretch a spring is Proportional to its Elongation: (Google Images) 6.2 Damping A tricycle suspension's travel speed and resistance is controlled by damping. It is the process wherein oscillations are controlled. The hydraulic gauges and valves in a shock absorber are employed to perform damping. If the tricycle is undamped, it will vibrate up and down thus it is necessary to design proper damping levels. Usually, tricycles and other vehicles control damping by varying the resistance to fluid flow in the shock absorber (Figure 6.2). Figure 6.2 Shock Absorbers: A - Piston; B - Cylinder; C - Piston Rod; D - Oil CHAPTER 7 MOTION MECHANICS Installing a good and durable tire for a recumbent tricycle is not enough. Even though tires are responsible for grounding the tricycle and affects other functions such as cornering and stopping, it is the suspension system's responsibility for 'keeping tires in contact with the ground so that they can do their job'. The suspension is required to 'accomplish this task over a wide spectrum of road conditions, while simultaneously giving a comfortable ride'. (Baker 2008)' 7.1 Front Fork Suspension In order to keep the front wheel in contact with the ground, front suspension is essential in any tricycle. Forks with internal springs and damping are frequently used for such purpose. Several brands with varying specifications and appearances are available in the market. An example is the one shown in Figure 4.1 (right image). Basically, 'the springs within the fork tubes are under compression, even when the tube has been removed from the tricycle'. This is called preload 'which essentially means the compression the spring is under when the suspension is not subjected to any weight'. The threaded adjuster on the cap of the fork is used to adjust the preload. (Baker 2008)' 7.2 Rear Suspension The rear suspension is made up of shock with an external spring (See Figure 8.1). Preload in the rear can be adjusted 'by lock rings or a ramp-type adjusting collar' (Baker 2008). ' ' Figure 7.2 Lock - ring Adjuster (Baker 2008) Figure 7.3 Ramp - type Preload Adjuster (Baker 2008) Baker (2008) provided a quick review of formulas that can be useful in suspension preload tuning which can also be applied in recumbent tricycles: ''''''' Static Friction1 = (A - B) - (A - C) ''''''''''''''''''' Static Sag2'= A - (B+C)/2 * ''''''''''''''''''' Free Sag3 = A - (B+C)/2 ** ''''''' Where: ''''''''''''''' ''''''''''' A = Full extension ''''''''''''''' ''''''''''' B = Suspension Measurement after Extend and Release ''''''''''''''' ''''''''''' C = Suspension Measurement after Compress and Release *Suspension Measurement with Rider(s) and Gear Onboard ''''''''''' **Suspension Measurement with Unladen Motorcycle CHAPTER 8 DEVELOPMENT AND DESIGN OF SUSPENSION BY SOLIDWORKS The Solid Works software proved to be an indispensable tool for creating, designing and simulating the shocks and springs system used in the suspension of the recumbent tricycle. Figure 8.1 shows the completed design of the shocks and springs system to be used for the rear suspension of the proposed recumbent tricycle. Figure 8.1 Shocks and Springs System The following images show the different parts of the shocks and springs system. (a) Brace (b) (c) Piston Rod (d) (e) (f) (g) Cylinder (h) Spring Figure 8.2 Shocks and Spring System Assembly Parts CHAPTER 9 MATERIALS FOR THE SUSPENSION SYSTEM The rear front fork suspension can be purchased readily in markets whilst the rear suspension should be assembled using acquired materials. The following tables4 provide a wide array of springs and suspension parts selection from which materials can be chosen for the manufacture of suspension. Table 1 Front Spring Selection Options Table 2 Rear Suspension Modification Options Table 3 Standard Springs CHAPTER 10 MANUFACTURING THE SUSPENSION The front fork suspension does not really have to be made; convenient types are available in the market. The rear suspension however, should be designed more carefully. The assembly of the rear suspension system is shown in Figure 10.1. Figure 10.1 Rear Suspension Assembly The system is designed to prevent the recumbent tricycle from banking when it passes through a bump or a gap. The action of the joints and the suspension is shown in Figure 10.2, 10.3 and 10.4. Figure 10.2 Rear Wheel Movements within the Suspension Frame Figure 10.3 When Rear Wheel Hits a Bump Figure 10.4 When Rear Wheel Hits a Hole CHAPTER 11 CONCLUSIONS This paper aimed to develop a suspension design for a recumbent tricycle especially intended to be driven single handed. The steering and braking mechanism was purposed to be made with dual brakes that can be actuated by one lever. Full suspension is integrated in the proposed recumbent tricycle for single - handed users; this means that it has front and rear suspension system. The front suspension simply made use of the front fork suspension common in other bicycles and tricycles. The rear suspension however, has been designed particularly to provide additional comfort and safety for a disabled user. It made use of shocks and external springs together with movable joints and axles. It has been shown that the rear suspension was prepared so that the tricycle will not bank if ever it hits a bump or a hole. Moreover, further improvements ought to be done and additional components should be added for a more dependable and safe suspension design. REFERENCES BAKER, DEAN. (2008). Suspension tuning: preload, viewed 21 May, 2009 . BIJKER, W. E. (1997). Of bicycles, bakelites, and bulbs: toward a theory of sociotechnical change, Edition 3. USA: MIT Press. FEHLAU, G. (2006). The recumbent bicycle. Grand Rapids, MI: Jeff Potter. GRIFFIN, HARRY HEWITT. (1885). The New York Times, Sept. 9, 1885 - bicycles & tricycles of the year 1886, viewed 21 May, 2009 . GRAHAM, B. & MCGOWAN, K. (2008). Bike, scooter, and chopper projects for the evil genius. USA: McGraw-Hill Professional. HEERKENS, G. (2001). Project management. U.S.A.: McGraw Hill. TRIPORTEURS. (2007). Page 3. History of tricycles, viewed 21 May, 2009 . SEARS, FRANCIS W., ZEMANSKY, MARK W., YOUNG, HUGH D. (1987). University physics, Seventh Edition. Addison - Wesley Publishing Company, Inc. Massachusetts, USA. SILLTECH INC. (2005). Suspension, viewed 21 May, 2009 . WILLIAMS, DAVID. (2009). Recumbent tricycles, viewed 21 May, 2009 . Read More