Athlon (Hand Powered Tricycle)

Fold Table of Contents Group Members Mission Statement Introduction Design Specifications Design Concepts Design Concepts (1-3) Concept Evaluation Design Overview Engineering Analysis (1-4) Gear Ratio Analysis Ratio of Rotations per Full Stroke Distance per Full Stroke Steering Ratio Force Analysis Bill of Materials Part Drawings Assembly Images Videos Implemented Design Summary and Conclusions

Group Members Andrew Coats Kevin Cunningham Stephen Hamilton Andrew Lykins Joseph Sumners

Mission Statement Our team mission is to build a hand-powered tricycle for ages 10 - 16+. This main goal of this device is to inspire physical activity and recreation for a growing child who has no use of their lower extremities.

Introduction For the fall of 2010, our team has chosen to design a whole new tri-wheeled device. This device is meant to inspire physical activity and recreation for children ages ten and up who have either lost, or never had the use of their lower extremities. The name we have chosen for our device is the Athlon, which is Greek for the verb meaning “to compete.” Because we do not have a specific child in mind for our design, we have decided that one of the initial requirements for the Athlon is that certain sections should be adjustable in length. We believe that this will not only allow the Athlon to be used by a variety of middle-school aged children, but that it will also be capable of simple extension to provide use for the child as they reach adulthood. Our second requirement is that the Athlon should be powered by both pushing and pulling forces generated by the arms. Additional specifications involve safety, lightness of weight, easy transitions for mounting and dismounting, steering, breaking, and gear shifting. We hope to implement a continuously variable transmission for the Athlon; however, the addition of CVT’s would dramatically increase the production cost.

Design Specifications General Design Requirements 1. Hand Powered only (acceleration, brakes, steering, gear shift) 2. Fully Size-Adjustable (for a growing child, including growing arm lengths) 3. Adjustable Strength (a geared bike should allow a stronger rider to change gears for a faster ride(and more exercise)) 4. Ease of use (can the person easily move from their wheelchair to the trike?) 5. Safety of the child 6. Desirability (Is it fun, does the child think it looks cool? Will he/she ride it?) 7. Cost (Will the design meet our budget requirements)

Design Concepts Our team is currently considering 3 designs. The first concept uses rotational motion to power the trike. It has two wheels in the front and one wheel in the back. With this design, each of the front wheels is independent of one another. Each has it own braking and acceleration. This design offers a high level of maneuverability. Our 2nd design is a row-action powered trike. It is the only design with one wheel in the front and two wheels in back. The power drive is 2-wheeled, meaning the back two wheels will be locked together, and the steering is left to the front single wheel. Our 3rd deign is the most complex. It encompasses a mix between the last two designs. This design would be row-action like the first, but have its two wheels in the front. Like the 2nd design, each of the front wheels will be independent of one another, giving the driver steering ability in pumping and braking. This last design is expected to be the most unique, but most expensive to manufacture. Concept Design Part Color Specification Part Color Framing Green Tires Yellow Mechanical Drive Red Revolutes Blue Suspension Orange Steering Bearing Purple Kinematic Motion White

Design Concepts (1-3) Design Concept 1 Design Concept 2 Design Concept 3 For our previous two designs, we utilized functional base models that have been successfully built and tested. Each of these models has their own set of advantages and disadvantages, but both have been proven in the field. Our third design is meant to distinguish a hybrid concept of hand powered tricycle that implements features from both of the previous designs. Because we have not yet witnessed a completed prototype of similar design, many specifications are yet to be determined. Seating, breaking, handles, and gear-shifting has not yet been incorporated into design. Pros: Open front with extendable mechanism can make independent mounting and dismounting from a wheelchair easier. Rowing levers allow direct push and pull power transfer. Independent drives allow a tight turning radius. Mountain bike swing arms are pre-manufactured and afford good suspension and gearing. Kinematic design and frame can support the addition of adjustable seating and levers to accommodate child development and passengers of different sizes. Small enough to fit in the bed of a pick-up truck. Cons: Dual drives increase the cost of parts and maintenance labor. Drive linkage places passenger load further from the turn radius center, increasing centripetal force experienced during a turn. Extended length and load placement may cause instability in rear wheel. Breaking failure in one of the front drive wheels at high speeds might cause sudden change in direction and possibly tipping.

Concept Evaluation Meeting with a team of three engineers, the project received some clarification. The biggest change would be the order of importance we ranked our different objectives. We were advised not to focus on adjust-ability. Issues like functionality, efficiency, and safety will be our core focus. The engineer group commented on several specific ideas. One concern was a child's ability to learn to drive on a bike that requires two seperate inputs. Would a child that has never rode a bike before struggle steering? Here our second design stands out in the simplicity of controls. Another concern is an overcomplicated design. We were advised that time and cost constraints should narrow the scope of our project to the points that matter. Again, the second design was chosen as the best choice. With a unanimous decision among the engineering group, Design 2 will now be the focus of our project. Rated 1-5; worst to best Consideration Design 1 Design 2 Design 3 Ease of Use: 3 5 4 Cost: 2 4 1 Learning Curve: 2 5 3 Motion/Manuv. 4 3 4 Ease of Construction: 3 5 1 Total 14 22 13

Design Overview Fully Assembled Side View Kinematic Motion Grashof Mechanism

Engineering Analysis (1-4) Our Analysis focus on the kinematic movements of our Bike. First we've chosen to look at a Gear Ratio Analysis, which looks mostly at gear teeth relations. Second, we've examined the Ratio of Rotations per Full Stroke and the Distance per Full Stroke, which take into account the CVT we will be using to gear the bike. Next the steering Ratio was examined. Here we look at input vs. turn angle to make sure the bike will turn properly. Lastly, we look at the drive system, measurements, and expected lengths of the drive system. Engineering Analysis 1 Engineering Analysis 2 Engineering Analysis 3 Engineering Analysis 4 Gear Ratio Analysis Part teeth circ (in) CW 28 CVP hub 20 CVP CW 44 Rear hub 20 Tire 62.83185307 (CW=Chain wheel) Ratio of Rotations per Full Stroke Gear Ratio Chain wheel CVP hub CVP CW Rear Hub 0.5 1 1.4 0.7 1.54 0.6 1 1.4 0.84 1.848 0.7 1 1.4 0.98 2.156 0.8 1 1.4 1.12 2.464 0.9 1 1.4 1.26 2.772 1 1 1.4 1.4 3.08 1.1 1 1.4 1.54 3.388 1.2 1 1.4 1.68 3.696 1.3 1 1.4 1.82 4.004 1.4 1 1.4 1.96 4.312 1.5 1 1.4 2.1 4.62 1.6 1 1.4 2.24 4.928 1.7 1 1.4 2.38 5.236 1.8 1 1.4 2.52 5.544 Distance per Full Stroke Gear Ratio Inches Feet 0.5 96.76128 8.06344 0.6 116.113536 9.676128 0.7 135.465792 11.288816 0.8 154.818048 12.901504 0.9 174.170304 14.514192 1 193.52256 16.12688 1.1 212.874816 17.739568 1.2 232.227072 19.352256 1.3 251.579328 20.964944 1.4 270.931584 22.577632 1.5 290.28384 24.19032 1.6 309.636096 25.803008 1.7 328.988352 27.415696 1.8 348.340608 29.028384

Bill of Materials Part Part # Quantity ID OD Length Width Cost/Part Cost Tricycle - Traditional 20" N/A 1 449.99 449.99 Seat 2680T58 1 132.13 132.13 Bearings 6384K61 3 .5" 1.125" .375" 6.90 20.70 Tubing (steel) 7767T43 1 1.26" 1.5" 6' 29.98 29.98 Tubing (steel) 9220K92 1 .402" .5 36" 7.15 7.15 Tubing (steel) 89955K86 1 .75" .875" 6' 27.85 27.85 Square Tubing (steel) 6527K31 1 .75" 1" 6' 1" 24.14 24.14 Rod (steel) 8924K35 1 .5" 6' 9.53 9.53 Rod (steel) 8924K33 1 .375" 6' 6.03 6.03 Rod Ends 1064K741 2 .375" 1" .5" 6.13 12.26 Elbow 4891T14 1 1.278" 1.66" 2.701" 16.40 16.40 Shaft Collar 9414T11 4 .5" 1" .4375" 0.79 2.37 Shaft Collar 9414T8 3 .375" .75" .375" 0.65 1.95 Connecting Rod 6516K22 1 .375" 12" 8.72 8.72 Pulley 3091T521 2 .5" 2" Guide: 1.625" .625" 12.45 24.90 Steel Flat Stock 8910K554 1 .25" 36" 1.5" 18.36 18.36 Steel Flat Stock 8910K941 1 .5" 12" 1.5" 12.48 12.48 Aluminum Sheet 8975K923 1 .125" 36" 5" 23.63 23.63 Aluminum Flat 8975K429 1 .5" 12" 4" 16.81 16.81 Aluminum Flat 8975K86 1 .25" 12" 4" 10.39 10.39 SS Cntersunk Screws 91771A539 1 .25" - 20 .625" 5.84 5.84 SS Cntersunk Screws 91771A537 1 .25" - 20 .5" 7.55 7.55 Total not including taxes or S&H 869.16

Part Drawings Original Tricycle #1 #2 #3 #4 #5 Top View of Drive System and Frame

Assembly Images Sorry, no photos. Videos The video below demonstrates the trike's Grashof Mechanism, which has 2 toggle points when the two bars are in parallel. To get around this we will attempt to use a magnetic assist to push/pull the bars through.

Implemented Design

Summary and Conclusions