Redesign of Mop Bucket and Wringer

FINAL REPORT DESIGN & PRODUCTION OF AN ALL – TERRAIN WHEELCHAIR

AGGRESSIVE DESIGNS From left: Connor Henley, Andrew Baigrie Miguel Tovar & Jeff Lance

University of Michigan College of Engineering ME450 Capstone Design Course Fall Term 2005 Executive Summary DESIGN & PRODUCTION OF AN ALL-TERRAIN WHEELCHAIR Andrew Baigrie • Connor Henley • Jeff Lance • Miguel Tovar

Of the 1.5 million Americans who use manual wheel chairs, roughly 600,000 are working age adults [1]. Currently, manual wheelchairs are not capable of any form of off-road travel without significant road harshness and external assistance. This paper presents the engineering scope of work necessary for a manual wheel chair redesign. The purpose of this report is to present our design, the fabrication process, and the final product of our project.

After developing an understanding of our product and redesign goals, we focused on evaluating our redesign components. A Quality Function Deployment chart was used to quantify the merits of our potential redesigns. From our QFD chart, we determined the characteristics for our design focus as the suspension, a 5th wheel, and the use of a recumbent seat.

After the selection of our design characteristics, we began to generate conceptual designs. Our product was decomposed into the two main design drivers: the suspension and the frame. For each driver five different concepts were generated and evaluated using Pugh Concept Selection matrixes. For the suspension, springs are the optimal dampening device for our application. For the frame, a single suspension design with a curved frame with a single suspension area was selected.

The main engineering challenge was to develop a design that would meet customer requirements while being structurally stable during off-road use. Finite element and structural analysis were performed on our design to ensure that it would be structurally stable. The geometrical constraints for the occupant were based on the current wheelchair of our primary customer. After developing a baseline frame design, we started to incorporate off the shelf components into our designing process (i.e. wheels, casters, shocks). We selected 6061 aluminum as the material for the frame based on machinability and cost considerations.

During the design phase of our project, we changed the scoping of the project and conscientiously made the collective decision to change some of the target design parameters. Changes in target weight and track resulted in usability gains that justified the deviation. Due to pricing constrains, we were not able to purchase shocks that permitted our target suspension travel. These deviations do not have an adverse affect on the performance of the final product. Additional validation was done over various terrains to ensure anticipated functionality.

The design and production processes illuminated a variety of areas for potential improvement. A redesign of the fifth wheel assembly would improve upon the current design, and power transmission could be developed and integrated to increase usability on steep terrain. Also, manufacturing improvements can also be realized through the production and use of a more precise jig.

TABLE OF CONTENTS

Introduction ...... 4 I. Engineering Specifications ...... 5

2 Customer Requirements ...... 5 Engineering Characteristics...... 6 Quality Functional Deployment ...... 7 II. Concept Generation ...... 8 III. Concept Selection ...... 11 IV. Selected Design Concept ...... 13 Concept Description ...... 13 Engineering Design Parameter Analysis ...... 14 V. Final Design ...... 17 Final Design Description ...... 17 Manufacturing Plan ...... 25 Project Validation ...... 28 VI. Engineering Changes ...... 29 VII. Discussion ...... 30 VIII. Recommendations ...... 31 IX. Conclusion ...... 32 X. Acknowledgements ...... 33 XI. Informational Sources...... 34 XII. References ...... 35 XIII. Appendixes ...... 36 Single Suspension Area Concepts ...... 36 Dual Suspension Area Concepts ...... 38 Tubing Dimensions ...... 39 Plate Geometry Dimensions ...... 40 Calculation of Suspension Load ...... 42 Three Point Bending Calculations ...... 43 Aluminum Tubing Properties ...... 44 FEA Output for Frame Analysis ...... 45 Bill of Materials ...... 47 Manufacturing Drawings...... 48

INTRODUCTION DESIGN & PRODUCTION OF AN ALL-TERRAIN WHEELCHAIR Andrew Baigrie • Connor Henley • Jeff Lance • Miguel Tovar

3 Of the 1.5 million Americans who use manual wheel chairs, roughly 600,000 are working age adults [1]. Despite significant design improvements in the last few decades, commercially available wheelchairs still lack the ability to provide users safe and affordable off-road accessibility. Typical wheelchair users are unable to access mountain trails and other off-road paths without significant after-market alterations or enduring hazardous passages with frequent assistance from others.

The wheel chair manufacturing industry has historically been dominated by large manufacturing firms. The firms have primarily focused the development of their “sport” chairs on increasing speed and maneuverability on hard surfaces. Currently, no marketplace offerings exist for a manual chair designed for extensive off-road usage. Wheelchair users must either use aftermarket alterations or powered chairs whose design and performance typically resemble small all-terrain vehicles. A manual off-road wheelchair would provide users the ability to travel in limited access areas with increased independence. . Customer research and competitive and lateral benchmarking were performed to develop an understanding of our product and redesign goals. A Quality Function Deployment chart was used to quantify the merits of our potential redesigns based on customer attributes. From our QFD chart, we determined the key focus areas for engineering: the suspension, a 5th wheel, and the use of a recumbent seat. The goal of this project was to design and prototype a wheelchair based on our customer attributes for off-road use.

I. ENGINEERING SPECIFICATIONS

CUSTOMER REQUIREMENTS

Both competitive and lateral benchmarking and customer surveying were performed to determine the most significant attributes for a wheelchair design in our target market. From this research, we developed the following customer requirements.

4 PRIMARY SECONDARY TERTIARY

Front and Back Suspension 5th Wheel

Off Road Rotate like Castor Capabilities 5th Wheel Larger, not castor size

Castor Style 5th Wheel Turning Easy To Maneuver Can easily traverse bumps/uneven terrain

Easy to move forward/backward

Fig. 1 Customer requirements for an all terrain wheelchair.

Additionally, our primary customer requested recumbent seating and easy transportation and storage. The customer was then asked to rank, in order of importance, attributes of wheelchair designs. These rankings are reflected in the QFD chart shown on page 7.

Currently, all commercially available manual wheelchairs still lack the ability to provide users safe and affordable off-road accessibility. The closest competitive product to an all-terrain design is the Quickie XTR. The XTR has limited suspension to reduce road harshness, but lacks the ability to traverse any type of rugged terrain and does not have recumbent seating for user comfort.

ENGINEREERING CHARACTERISTICS

The engineering characteristics were derived from the customer attributes using customer rankings and quality functional development charts. These characteristics are the driving factors in a new design to best meet the customer’s needs. They are summarized in the table below:

Characteristic Current Design Target Force Required to 12 lbs 12 lbs Move Horizontal/Vertical 20/20 in 20/18 in. Location of Center

5 of Mass Weight 35 lbs 25 lbs Suspension Travel 0 2 in. Wheel Base/Track 38/18 in. 40/18 in.

Table 1: Engineering characteristics for all-terrain wheelchair.

The relationship between the customers’ attributes and the engineering characteristics are shown on page 7 in the QFD chart. The QFD is a tool that was used to translate customer requirements into design requirements. The QFD allows for quantitative ranking of design requirements that drive the design process of the project. For our project, the most important engineering design goals are: decreased road harshness, a rotating 5th wheel, and a recumbent seat.

6 Fig. 2: QFD chart for all terrain wheelchair.

7 II. CONCEPT GENERATION

The driver design areas for our project can be decomposed into two major areas: suspension and frame.

DESIGN DRIVER: SUSPENSION

Three types of suspension were researched for our project application. These types were coil over- springs, leaf springs, and scissor dampening. Some examples of these components are provided in the concept selection matrix, shown as Fig. 9 on page 11.

DESIGN DRIVER: FRAME

Numerous drivers exist for the design of our frame. The impact of these drivers varied throughout our brainstorming sessions, as we shifted our focus priorities. The majority of concept brainstorming was performed on chalk boards, but sample sketches of some preliminary design concepts are provided in Appendix A on page 36.

Fig. 3: Benchmark of current market wheelchair.

The datum for our project (concept 1) is shown above. After-market installation of a fifth wheel increases the off road mobility; however, road harshness and comfort are main determents to user satisfaction. Additionally, the chair has insufficient ground clearance and poor maneuverability and aesthetics.

8 Figure 4: Four competing designs.

From our preliminary design, we selected four promising designs to develop further and improve in CAD models. These competing designs are shown above in figure 4, and were evaluated in the concept selection matrix shown as Fig. 10. on page 12 to select the Alpha Design.

Fig. 5: Concept two introduces a curved frame design and rear suspension.

Concept two, shown above highlights a design class with rear suspension and fixed structural based front end. This design is structurally robust and strongly constrained to attempt to direct the dampening.

9 Fig. 6: Concept three uses rear suspension with slip joints and long curved structural bars.

Concept three highlights a design that also is based on a rear suspension that utilizes a slip joint to increase the dampening range. The structure is driven by large curved tubing.

Fig. 7: Concept four uses front and rear suspension, the structure is based on a single curved bar.

The design of concept four is driven by having dual suspension areas. The dual suspension areas create a structure which is supported by a single curved bar.

Fig. 8: Concept five uses only straight tubing and a single suspension area.

This design is driven by the use of only straight aluminum members. The use of straight bars mandates a single suspension area based on weight and manufacturing and disassembly constraints.

III. CONCEPT SELECTION PROCESS

DESIGN SELECTION: SUSPENSION

Subsystem: 1 2 3 4

10 Empty bucket

Road Harness 0 + + + Volume requirements 0 0 - - Production Costs 0 0 - 0 Safety 0 + - + Durability 0 0 0 0 Weight 0 0 - - Sigma + 0 2 1 2 Sigma - 0 0 4 2 Sigma S 6 4 1 2 Rank 3 1 4 2

Fig. 9: Pugh chart for suspension subsystem.

Based on the Pugh chart developed for the suspension subsystem, using springs as the damping element is the optimal design. A spring based suspension will allow a significant reduction in road harshness without compromising safety or additional space. The design has minimal additional cost and significantly increases the functionality of the overall system.

DESIGN SELECTION: FRAME

Subsystem: Frame 1 2 3 4 5

11 Road Harness 0 + + + + Weight 0 0 0 0 - Production 0 0 0 - 0 Costs Ease of 0 0 + - - Manufacture Aesthetics 0 + + + - Ease of 0 + + + 0 Disassemble Sigma + 0 3 4 3 1 Sigma - 0 0 0 2 3 Sigma S 6 3 2 1 2 Rank 4 2 1 3 5

Fig. 10: Pugh chart for frame subsystem.

Based on the Pugh chart developed for the frame subsystem, design number three is the optimal design. Design three improves over the datum frame in four customer requirements without compromising performance in the other requirement areas of concern. Design three offers a significant aesthetic improvement, while dampening road harshness and allowing for easier manufacturing and disassembly.

IV. SELECTED DESIGN CONCEPT

CONCEPT DESCRIPTION

12 Our final concept fulfills the customer requirements as discussed above and is shown below as Fig. 11. Through concept selection the two main subsystems were identified and chosen in section 2. The final concept adds the five pneumatic wheels to the design. Detailed engineering drawings are provided in section V which begins on page 17.

Fig. 11: Selected design concept.

The increased maneuverability for our design is based off the use of a fifth wheel. The fifth wheel allows the user to distribute their weight over the rear half of the chair. This distribution and the associated user position allow the drive wheels to contact obstacles first. The initial drive wheel contact increases the ability of users to traverse obstacles. The drive wheels size and relation to the user position create a change in magnitude and direction of the force that is applied to overcome obstacles.

Fig. 12: Operational diagram for selected design.

ENGINEERING DESIGN PARAMETER ANALYSIS

The engineering calculations were driven by the comfort and safety of our customer. Competitive and lateral benchmarking was performed to research design approaches. From these designs and customer interviews, a basic geometry for our design was developed. The geometry was first tested with basic dynamic calculations to determine the maximum loads that our frame would see during extreme usage conditions. After our preliminary geometrical design was tested, off-the-shelf components were researched and integrated into the design. Material selection was chosen based on machinability, cost constraints, and weight and strength considerations. Our material selections were validated using basic materials calculations. Using the loads from our dynamics calculations, we located key stresses and

13 weaknesses in our design. Finite element analysis (FEA) and hand calculations were used to validate our final design.

Basic Geometry The basic geometry of our wheelchair design was driven by the dimensions of our main customer. Using measurements taken from an existing chair, we defined the locations of critical locations such as the five wheels and the occupant. Other components, such as arm and foot rests, were also designed to fit our customer. The second driver of our frame design was the inclusion of suspension.

Suspension Forces A worst case loading scenario was used to calculate the loads applied to our frame. For the worst case scenario, the shock is replaced by a rigid link and a force twice the predicted mass of the wheelchair and rider was applied to the two wheels. This loading simulates the wheelchair and rider landing from a fall without any dampening from the suspension. A simplified drawing of this case is shown below in Fig. 13. Using basic dynamics tools, we determined the reaction forces applied by our frame at the pivot points of our suspension. These forces are summarized below where positive x is to the right, positive y is towards the top of the page and positive z is out of the page. Ax is the force applied by the frame at point A in the x-direction and so on. The complete calculation can be found in Appendix E on page 42.

Ax -27.03 lbs Ay -257.14 lbs Bx 27.03 lbs By 57.14 lbs

Fig. 13: Model used for calculating suspension forces.

Off-the-Shelf Components Commercially available components were included when possible in the design. These components have been commercially proven and are easier for the consumer to service and repair. For example, commercial rod ends were purchased to serve as the pivot points for our trailing arm. The rods ends must withstand the suspension loads calculated above. We selected rod-ends from high strength steel that are capable of withstanding tensile forces of over 16,000 lbs. Other items we purchased include mountain bike style wheels, quick-release axle components, caster assemblies, bearings, and shocks.

Material Selection Material selection was chosen based on machinability, cost constraints, and weight and strength considerations. Our basic materials knowledge suggested that 6061 aircraft aluminum would be a good choice due to its strength to weight characteristics, as well as its good machine-ability and weld-ability. Cost analysis of other materials confirmed our selection, and we selected 1 inch outer diameter tubing with a wall thickness of 1/8 inch. The physical properties of this material can be found in Appendix G on page 44.

Material Verification The material was verified using the suspension loads found above. As shown in Fig. 14. the stress was calculated for a simply supported beam of aluminum tubing. The maximum stress predicted for our

14 design is approximately 5,800 psi located above each shock. Therefore, our safety factor for the tubing of the wheelchair is over 6. T he complete calculation of this value is shown in Appendix F on page 43.

Fig. 14: Three point bending model.

Finite Element Analysis Altair Hypermesh was used to build a finite element analysis (FEA) model for our project. A screen shot of the FEA model is shown below in Fig. 15. In this model, the chassis is represented using simple bar elements. The bar elements have been defined to have the same properties as the aluminum we plan to use to build our chassis. The forces from the previous hand calculations were then applied to the chassis at the points where the suspension attaches. The frame was held in position by constraining the two front wheel locations as well as the back rest from moving in the x, y, and z-directions. Stress was measured at four places on both ends of each bar. These stress recovery points were located on the top, bottom, and on either side of the tube as shown in Fig. 15. The maximum stress predicted by our model was 7,800 psi, which is well below the yield strength for 6061 aluminum. As predicted in our earlier analysis, the maximum stress was located on the top surface of the horizontal bar where the shock load is transferred to the chassis. The output from the FEA software can be found in Appendix H on page 45. Since both our hand calculations and FEA model agree, we feel that we can trust our numbers and say that the frame will hold up under suspension loads.

Fig. 15: FEA model of wheelchair frame and specified stress recovery points.

Finite element analysis was also performed on the main connection plate where our trailing arm meets the axle and shock. These four plates support the two large drive wheels and must not fail under suspension loads. Altair Hypermesh was used to build a two dimensional shell model of the plate as shown below in Fig. 16. The model was constrained along the bottom and along the right edge. These are the locations

15 where the plate will be welded to the trailing arm. The smaller hole on the left hand side of the plate was loaded vertically with the same force found in the hand calculations above. The load was only applied to the bottom half of the hole, because, under load, the bolt will only apply compressive forces. Similarly, the axle loads on the right hand hole were applied only to the top half. Figure 16 shows a color coded representation of the stresses in the plate. Blue areas see little or no stress while red ones are experiencing maximum stress. According to this model, there should not be more than 1,600 psi of stress in the connecting plates. These values are well below the yield strength of 40,000 psi and we are confident that they will not fail.

Fig. 16: FEA analysis of Axle Plate.

V. FINAL DESIGN

FINAL DESIGN DESCRITPTION

Shown below in Fig. 17 is our final design.

Fig. 17: Final wheelchair design.

16 Frame The frame for our wheelchair is constructed with the aluminum tubing that was discussed and analyzed in the previous section. The different lengths that will be cut and shaped can be found in Appendix C on page 39.

The major dimensions of our project are shown below in Fig. 18 below.

Fig. 18: Major dimensions of final wheelchair design.

As shown above in Fig. 18, the design dimensions meet our Engineering Specifications that were discussed on page 6.

A more detailed drawing, showing additional frame dimensions and part call outs is shown below in Fig. 19. Seat Back

17 Arm Rest Caster Attachment Attachment Attachment Supports Support Point

5th Wheel Support Foot Rest

Trailing Arm Caster Attachment Point

Fig. 19: Detailed drawing of the frame with dimensions and part call-outs. .

The attachment supports that we will be using for attaching our arm rest, seat back and 5th wheel support will be constructed of 6061 aluminum tubing with 0.75 inch OD and 0.125” wall thickness. These supports will be 3” long to allow for 1.5” of each portion of tubing in each section.

Arm Rest A detailed drawing of our arm rest assembly is shown below in Fig. 20.

18 Attachment Supports

Fig. 20: Detailed drawing of arm rest.

The arm rest design has 3 inches of height adjustability and five possible position settings. The arm rest slides on the attachment supports as shown above and will be secured in location with either cotter pins or easily removable bolts.

Seat Back A detailed drawing of the seat back is shown below in Fig. 21.

Attachment Supports

Fig. 21: Detailed drawing of seat back.

The seat back will be attached in a similar manner to the arm rest.

Fifth Wheel Support The fifth wheel support is shown in the detailed drawing below in Fig. 22.

19 Bearing Housing

Attachment Supports

Fig. 22: Detailed drawing of the 5th wheel support.

The fifth wheel support will be attached to the frame in a similar manner as the seat back and arm rest. The support will also house the two bearings for the rear caster. The bearings will be 1.125” OD with a 5/16” ID, and they will be pressed into aluminum tubing. The tubing will be welded to the legs as shown above to form the support for the firth wheel. The bearings will be spaced 1.25” apart and a 2” bolt used to attach the fifth wheel to the support.

Casters A drawing showing our caster attachment is shown below in Fig. 23.

Length of Caster Fork Bearing Housing

Caster Fork

Caster Wheel

Fig. 23: Caster attachment plan.

Different caster wheels will be used for the rear and front wheels as discussed above. These wheels will be bought commercially and will attach to the caster fork using 5/16” bolts. The front caster forks are 7” long and will be purchased. The rear caster fork will be 13” long and made out of 1/8” thick aluminum plate. The caster forks will attach to the bearing housing with a 2” x 5/16” bolt.

Trailing Arm A detailed drawing of our trailing arm and the suspension is shown below in Fig. 24.

20 Trailing Arm Shock Shock Plate Plate

Axle/Axle Sleeve

Re-enforcing Tube Rod End Axle Plate Trailing Arm

Fig. 24: Detailed drawing of trailing arm and suspension.

A rod end will be used to attach the trailing arm to the frame and trailing arm plate. Stainless steel JMX8 rod end from FK Rod Ends have been selected. The rod end will act as a pivot point, allowing the trailing arm to articulate up and down.

The axle is a ¾ x 16 threaded tube. We plan on tapping aluminum tubing and having the axle screw into the axle sleeve. Thread sealant and an axle nut will be used ensure a tight fit. The axle sleeve will be welded to the axle plate.

The three plates shown in Fig. 25 will be made of ¼” thick 6061 aluminum plate. They will be welded to the trailing arm or frame. Detailed drawings of each can be found in Appendix D.

A re-enforcing tube is used to prevent the axle plate from rotating during loading. The tubing also links the rear suspension so that both wheels move with each other and are not independent. An independent suspension would require users propel the wheelchair with the user’s arms at two different positions.

Foot Rest A detailed drawing of the foot rest is shown below in Fig. 25.

The foot rest will also be constructed out of ¼” thick 6061 aluminum plate. The foot rest was designed with many holes; both for aesthetics and to lighten the part. The part will be welded onto the front-most tube of our frame. From user testing, we determined the optimal angle for the foot rest to be 30 deg above horizontal.

21 Fig. 25: Detailed drawing of the foot rest.

Parts List The major components that were used to build the wheelchair are shown below in Table 2. A detailed bill of materials is shown in Appendix I on page 47.

Qty. Part Manufacturer Cost (total) 4 1" OD x 1/8" wall Aluminum Tubing (12 ft. section) Alro $122.00 2 1 1/4" OD x 1/4" wall Aluminum Tubing (3 ft. section) Asap Source $60.00 1 3/4" OD x 1/8" wall Aluminum Tubing (3 ft. section) Alro $12.14 1 1/4" x 12" x 24" Aluminum Plate Asap Source $52.92 1 26x2.1" Off Road Rear Wheels Sport Aid $299.00 1 6" x 1 1/4" Pneumatic Caster Sport Aid $59.00 1 12" x 1 1/4" Scooter Wheel EBAY $10.00 2 5" slotted Aluminum Caster Fork Sport Aid $60.00 4 5/16" Caster Bearings Sport Aid $20.00 1 1/2" diameter X 4 5/8" length Quick Release Axle Sport Aid $55.00 2 1/2" diameter Quickie Axle Sleeve Sport Aid $35.00 4 3/4" x 16 Quickie Axle Sleeve Nut Sport Aid $4.40 2 1" travel Shocks EBAY $57.00 2 JMX-8 Rod Ends for Trailing Arm FK $40.00 1 30’ Seat Belt Material General Motors $150.00

Table 2: Parts list for major components.

22 MANUFACTURING PLAN

A detailed fabrication plan is provided in table 3 on page 25. Figs. 26-29 are provided for identifying parts.

Fig. 26: Chair frame labeling scheme.

Fig. 27: Arm rest labeling scheme.

23 Fig. 28: Fifth wheel fork labeling scheme.

Fig. 29: Seat back labeling scheme.

24 Step Machine/Speed Circular Saw - 4500 Cut base for jig out of plywood rpm Circular Saw - 4500 Cut supports for jig out of 2 x 4 's rpm Measure locations of supports on plywood base Screw necessary supports together Screw supports to plywood base Cut bar A Band Saw - 300 ft/min Bend bar A to proper radius Hydraulic Bender Attach both bar A's to jig using duct tape Cut bar L Band Saw - 300 ft/min Mill ends of bar L to create fit with bar A Mill - 1200 rpm Attach bar L to jig using duct tape Cut bar H Band Saw - 300 ft/min Bend bar H to proper radius Hydraulic Bender Mill bar H to create fit with bar A Mill - 1200 rpm Cut bar C Band Saw - 300 ft/min Cut bar N Band Saw - 300 ft/min Mill bar N to create fit with bar C Mill - 1200 rpm Cut bar V Band Saw - 300 ft/min Cut bar W Band Saw - 300 ft/min Cut bar X Band Saw - 300 ft/min Mill bar V to create fit with bar W Mill - 1200 rpm Mill bar X to create fit with bar V Mill - 1200 rpm Turn bar 3 so that it very tightly fits inside bar C Lathe - 500 rpm Press fit bar 3 into bar C Press File bar 3 so that it smoothly slides into bar V Slide bar 3 into bar V Drill a hole through the center of where bar 3 and V connect Drill Press - 2000 rpm Remove bar 3 from inside bar V Remove bar A from jig Mill end of bar A to create fit with bar C Mill - 1200 rpm Reattach bar A to jig with duct tape Attach bar H to jig, should rest between the two bar A's Remove all duct tape from jig and attach bars to jig with clamps Cut bar 1 Band Saw - 300 ft/min Turn bar 1 so that it fits tightly into bar N Lathe - 500 rpm Press fit bar 1 into bar N Press Tack weld bar V to bar W Welding Torch Tack weld bar X to bar V Welding Torch Tack weld bar A to bar L Welding Torch Tack weld bar N to bar C Welding Torch Tack weld bar H to bar A Welding Torch Tack weld bar C to bar A Welding Torch Cut bar M Band Saw - 300 ft/min Mill ends of bar M to create fit where bars A and L meet Mill - 1200 rpm Cut bar I Band Saw - 300 ft/min

25 Mill ends of bar I to create fit with bar M at one end and bar A at the other Mill - 1200 rpm Attach bars I and M to jig with clamps Tack weld bar M at joint with bars L and A Welding Torch Tack weld bar I to bar M and bar A Welding Torch Cut bar B Band Saw - 300 ft/min Cut bar D Band Saw - 300 ft/min Attach bar D to jig with duct tape Mill ends of bar B to create fit with bar D Mill - 1200 rpm Bore out bar D to create fit for caster fork bearings Lathe - 500 rpm Attach bar B and bar D to jig using clamps Tack weld bar B to bar D Welding Torch File bar 1 until it smoothly slides into bar B Drill hole through center of where bar B and bar 1 overlap Hand Drill Mill axle plate, shock plate, and trailing arm plate CNC Mill Mill foot rest plate CNC Mill Cut bar E Band Saw - 300 ft/min Cut bar F Band Saw - 300 ft/min Cut bar G Band Saw - 300 ft/min Clamp bar E, bar F, bar G and the trailing arm plate in the proper orientation Finish weld trailing arm assembly together Welding Torch Tack weld foot rest plate to bar L Welding Torch Attach trailing arm assembly to jig Determine location of axle plate on bar A Clamp axle plate to bar A Tack weld axle plate to bar A Welding Torch Determine location of shock plate on bar A Clamp shock plate to bar A Tack weld shock plate to bar A Welding Torch Cut bar K Band Saw - 300 ft/min Bore out bar K to create fit for caster fork bearings Lathe - 500 rpm Cut bar J Band Saw - 300 ft/min Mill bar J to create fit with bar K Mill - 1200 rpm Attach bars K and J to jig with clamps Tack weld bar K to bar M Welding Torch Tack weld bar J to bar K Welding Torch Cut bar 2 Band Saw - 300 ft/min Cut bar P Band Saw - 300 ft/min Cut bar Q Band Saw - 300 ft/min Cut bar R Band Saw - 300 ft/min Cut bar S Band Saw - 300 ft/min Cut bar R to create an angled fit with bars Q and S Band Saw - 300 ft/min Mill bar P to create fit with bar Q Mill - 1200 rpm Turn bar 2 so that it slides easily into bar P and S Lathe - 500 rpm Clamp bars P,Q,R, and S together Tack weld arm rest assembly together Welding Torch Tack weld bar 2 to bar A Welding Torch Slide arm rest assembly onto bar 2

26 Measure locations of where arm rest should adjust to and mark Drill holes in bar 2 and arm rest assembly where marked Hand Drill Cut plate T and U Band Saw - 300 ft/min Drill Hole through center of plate U Drill Press - 2000 rpm Drill Hole in plate T where axle for fifth wheel will be located Drill Press - 2000 rpm Clamp plates T and U together Finish weld plate T to plate U Welding Torch Cut triangular plate supports Band Saw - 300 ft/min Tack weld triangular plate supports at joint of plate T and plate U Welding Torch Finish weld all parts that were previously only tack welded Welding Torch Sand and file frame Spray paint frame Put rod ends in the end of bar E Attach rod end to axle plate using a bolt Attach shock to trailing arm plate using a bolt Attach other end of shock to shock plate using a bolt Attach ratchet straps to bar V to create a back for the seat Attach bar V to bar 3 using screw Attach wooden base over top of the two bar H's to create a base for seat bottom Attach two main drive wheels to frame (bar G) Attach two front casters to frame (bar K) Attach rear wheel caster to frame (bar D) Attach arm rest assembly (slide bar 2 into arm rest assembly and insert screw) Attach bar B to bar N and insert screw

Table 3: Manufacturing plan.

PROJECT VALIDATION

27 The usability of our project drives our design validation. The majority of our engineering specifications were dimensional design drivers. Therefore, our design is based on and fulfills the majority of the engineering specifications. The final product exceeds the weight and wheel track that we had established in our initial target. During the design phase of our project, we changed the scoping of the project and conscientiously made the collective decision to change the design parameters. The increased weight and track resulted in usability gains that justified the deviation from the target. Due to pricing constrains, we were not able to purchase shocks that permitted our target suspension travel. Though this characteristic was not fulfilled, the deviation is not noticeable or detrimental to the use and appeal of the final project. The only engineering specification that was not a dimensional constraint was the force required to move the chair. This was measured using a digital spring scale as done during our competitive benchmarking. The engineering specifications are shown below in Table 4.

Characteristic Target Final Design Force Required to 12 lbs 12 lbs Move Horizontal/Vertical 20/18 in. 20/18 in. Location of Center of Mass Weight 25 lbs 30 lbs Suspension Travel 2 in. 1.5 in. Wheel Base/Track 40/18 in. 35/21 in.

Table 4: Engineering characteristics for all-terrain wheelchair.

Additional project validation was performed in a variety of locations around Ann Arbor to establish performance and identify recommendations for product usage and potential future work. This validation included usage over a variety of terrain that would be characteristic of the intended use including log and rock climbing, stream crossings, hill assent and decent and washboard trails.

VI. ENGINEERING CHANGES

28 1

2 1

3 2

4 3

Fig. 30: Design changes from initial concept shown on the left, to the final design on the right.

1. The seat back support was removed to increase user comfort and facilitate removal of the seat back. The change was authorized by the entire group on 12/1/05.

2. The angle of the 5th wheel support was increased to enhance comfort and usability. The initial angle was too shallow and required excessive force from the user to maintain a reclining position. The angle was also increased to allow the castor fork to be in a horizontal position, which allows the rear wheel to turn with less force. This change was approved by the entire group on 11/29/05.

3. Plating was added to increase the strength of the 5th wheel support and the seat back. This modification prevents removal of the 5th wheel support from the frame. The change was approved by the entire team on 11/21/05 to ensure a robust attachment.

4. The design of the handle support was changed to allow for a variety of users. The vertical tubes were reattached to the side of the chair instead of directly attaching them to the top of the seat. This modification increased the width of our chair by 2”, allowing for wider people to fit. This changed was approved by the entire group on 11/30/05.

VII. DISCUSSION

Our completed prototype fulfills the proposed customer requirements. The design and production processes both illuminated opportunities for improvement and areas of potential future work. Based on our experience, our design recommendations focus on the fifth wheel assembly and power transmission. The current fifth wheel assembly experiences significant free rotation of the back caster during use. The free rotation of the caster hinders tight maneuverability by changing the orientation of the tire when jarred

29 on rugged terrain. Another design possibility for increased functionality is the addition of power transmission to the chair. The power transmission would allow users the option to either push or pull on the wheel handrails to move forward. The power transmission could be accomplished by using a toggle gearing mechanism that could be shifted while parked. The ability to pull would allow users a significant advantage while climbing hills and would help decrease user fatigue.

Areas for improvement in manufacturing were identified during production of the prototype. A wooden jig was constructed to ensure the correct orientation of components during assembly and welding. Our jig was constructed with standard contractor equipment and had significant tolerances relative to component sizes. For future projects, we recommend the production of a high precision jig. The time invested in a jig has a significant payback during the manufacturing phase.

VIII. RECOMMENDATIONS

SYSTEM LEVEL

Our basic system design has been successful in addressing the consumer attributes. The suspension on the main drive wheels was an effective way to fulfill the customer’s comfort requirements while the rotating fifth wheel allowed for both increased turning and increased off- road capabilities. We recommend that future of-road wheelchairs continue to use this five-wheel setup. Improvements in maneuverability and usage can still be easily addressed in future designs. Maneuverability can be enhanced with changes in camber and materials selection. We recommend that future chairs incorporate drive wheels designed with negative camber as commonly found on commercially available chairs. During the design phase we made the trade

30 off between chair width and camber. In retrospect, we would recommend the additional width to increase turning and maneuvering capabilities. Additionally, the weight of the chair could be decreased with the appropriate manufacturing and costing availability. Further analysis and testing of the frame could reduce the wall thickness on tubes and plates. Usability could also be enhanced with additional suspension. Both the fifth wheel and front casters could incorporate suspension to decrease vibrations felt by the user. A commercial product made by Frog Legs is currently available but was omitted from our design for cost reasons.

COMPONENT LEVEL

Cost was a driving factor in our component selection. Based on future costing and availability, multiple areas of the design could be optimized with component changes. Our selected shocks were very competitively priced, but they lack adjustability and have excessive damping. The selection of coil over shocks with adjustable damping and 150lbs/in springs would greatly improve the suspension performance. The suspension design could be improved further by reselecting rod-ends for use as the front pivots. The current rod-ends were donated and are oversized for our needs and weigh 1/4 lbs each. By decreasing the size of these components, the weight of the chair could be reduced without weakening the structure. The tires that were chosen were one of the greatest strengths of the project. During testing we found they provide enough traction on slippery or muddy surfaces. They are also strong enough to take whatever punishment that the user can put them through.

The design of the fifth wheel attachment could also be optimized. Initially, the rear wheel attachment in our prototype required excessive force from the user to maintain the reclined position. To correct this we raised the rear wheel by tilting the rear arm upward. This modification slightly hinders the ability of the wheel to swivel freely. While the current prototype is functional, in future designs it is critical that the swivel axis be vertical for the rear wheel to function smoothly as a caster.

IX. CONCLUSION

The selected concept for our project was developed based on the optimal integration of the most important engineering design goals: decreased road harshness, a rotating 5th wheel, and a recumbent seat.

The final design incorporates five wheels; two front castors, the two drive wheels, and a fifth wheel in the back. The fifth wheel on the back of the chair makes it easier to traverse over objects and rough terrain. Additionally, the seat back and bottom form a ninety degree angle, but the whole seat is tilted at a five degree angle. This helps relieve some of the pressure that is placed on the lower back and makes the ride more comfortable.

31 From the FEA analysis done on the frame, the stresses that the frame will see are considerably less than the yield strength of the 6061 aluminum that was used. The frame for our design has a safety factor of over 5, and the connecting plates have a safety factor of over 25. These safety factors ensure safe operation and flexibility of our design.

Engineering changes were made from the original design concept to the final design. The angle on the back wheel attachment was altered to make the ride more comfortable. By increasing the angle, it makes it easier for the rider to stay on the fifth wheel. Additionally, the cross bar that ran across the top of the seat was removed to increase the comfort of the rider. The attachment of the arm rest was also altered, which allows the wheelchair to accommodate a wider rider than it could with the previous design.

X. ACKNOWLEDGEMENTS

ME Design and Manufacturing Machine Shop: Mr. Robert Coury & Mr. Marvin Cressey

ME 450 Instructional Team: Professor Albert J. Shih & Mr. Scott Miller School of Art & Design Metal Studio: Mr. Chris Whaley

University of Michigan Hospitals, Biomedical Engineering: Mr. Patrick Lobbestael

ProCEED: Mr. Peter Adamczyk

Adaptive Materials Inc, Ann Arbor, MI

Ms. Julie Harrison

XI. INFORMATIONAL SOURCES

Primary users provided the baseline and target data from which design benchmarking and brainstorming began. Our primary customer contact provided the initial data through the introductory interview. Specifically, she gave a general overview on current wheelchairs usability and potential areas for improvement. Additionally, she provided introductions and assisted in obtaining feedback from other users to increase our knowledge about the target population.

Current wheelchair designs were examined and evaluated for benchmarking purposes. Data was obtained by hands-on testing and reference material that was found through product literature (owners’ manuals), advertisements, and online forums and sales outlets. This information broadened our knowledge database of current production chairs and after market enhancements. Specially, we focused on all-terrain and other athletically targeted wheelchairs (rugby, basketball, etc.). The benchmarking exercises allowed us to generate the data that drives our engineering specifications.

While there have been a few attempts for traditional manual wheelchairs to expand their road handling, we have found no constraining patents in our searches. In particular, we have focused our search effort on rear suspensions and fifth wheel designs, without finding any possible conflicting patents.

33 XII. REFERENCES

[1] Kaye, Stevens, et al. “Wheelchair Use in the United States.” Disabilities Statistics Center, University of California. May 2002.

[2] Brethour, Patrick. “Wheels of freedom, and fortune.” Globe Investor. August 15, 2005

[3] Invacare, “Product Catalog,” September 14, 2005.

[3] Invacare Corporation, “A-4 Owner’s Operator and Maintenance Manual”, 1999

[4] Harrison, Julie, Personal Inteviews, September 15th and 21st, October 18th, 2005.

[5] eFunda, “Properties of Aluminum Alloy AA 6061,” Accessed on October 19th, 2005,

34 XIII. APPENDIXES

APPENDIX A: SINGLE AREA SUSPENSION CONCEPTS

Fig. A.1: Sketch of single rear suspension with curved support bars.

35 Fig. A.2: Sketch of rear suspension with lower center of mass structural support.

Fig. A.3: Sketch of possible suspension for seat.

36 Fig. A.4: Sketch of possible leaf design for suspension.

Fig. A.5: Sketch of rear suspension design with curved arm.

APPENDIX B: DOUBLE AREA SUSPENSION CONCEPTS

Fig. B.1: Double suspension sketch with extensive bending in production.

37 Fig. B.2: Dual seating suspension concept.

Fig. B.3: Dual “Bus Driver” seat suspension concept.

APPENDIX C: TUBING DIMENSIONS

Length Total Length Item Quantity (in) (in) 10" Radius 2 40 80 Trailing Arm 2 24 48 Seat Vert. Supports 2 18 36 Top/Horrizontal Seat Back 1 15 15 Arm Rests 2 17 34 Seat Bottoms 2 16 32 Trailing Arm Connector 1 18 18 5th wheel extension 2 18 36 Foot Rest 1 12 12 Front Caster Connector 1 12 12 Connect Caster to Foot Rest 2 8 16 Connect Caster to 10" Radius 2 11 22

Front Caster Tube (1/2" wall) 2 5 10 Rear Caster Tube (1/2" wall) 1 5 5

Table C.1: Lengths of the tubing that will be used to build our wheelchair.

38 APPENDIX D: PLATE GEOMETRY AND DIMENSIONS

Fig. D.1: Detailed drawing of the Axle Plate, four parts will be made.

39 Fig. D.2: Detailed drawing of the Shock Plate, four parts will be made.

Fig. D.3: Detailed drawing of the Trailing Arm Plate, four parts will be made.

40 APPENDIX E: CALCULATION OF SUSPENSION LOAD

Fig. E.1: Model used for calculating suspension load.

41  M B  0  200(310.5) T cos6(10.5)  200(310.5)  T  10.5cos6  T  258.56lbs

 Fx  0  Bx T sin 6

 Bx  27.03lbs

 Fy  0  200 T cos6  By

 By  T cos6  200

 By  57.14lbs

 Fx  0  Bx  Ax

 Ax  27.03lbs

 Fy  0  200  By  Ay

 Ay  257.14lbs

APPENDIX F: THREE POINT BEAM BENDING CALCULATIONS

Fig. F.1: Three point beam bending model.

42 Mc   m I 1 M  FL 4 1 I   (r 4  r 4 ) 4 o i 1 FLc   4 m I 1 (130)(12)(0.5)   4 m (0.033556)

  m  5811psi

APPENDIX G: MATERIAL PROPERTIES OF 1”OD 0.125”WALL 6061 ALUMINUM [5]

Elastic Modulus, E, psi 10,000,000 Poisson’s Ratio, ν 0.33 Density, ρ, lbs/in3 0.0975 Tensile Strength, psi 45,000 Yield Strength, psi 40,000 Cross Sectional Area, A 0.344 Moment of Inertia, I, in4 0.0336 Table G.1: Material Properties

43 APPENDIX H: FEA OUTPUT DATA FOR FRAME ANALYSIS

STRESSES IN BAR ELEMENTS (CBAR) ELEMENT SA1 SA2 SA3 SA4 AXIAL SA-MAX SA-MIN ID. SB1 SB2 SB3 SB4 STRESS SB-MAX SB-MIN 1 9.87E+00 -3.20E+01 -9.87E+00 3.20E+01 0 3.20E+01 -3.20E+01 -9.92E+00 2.95E+01 9.92E+00 -2.95E+01 2.95E+01 -2.95E+01 3 5.79E+00 -2.74E+03 -5.79E+00 2.74E+03 -3.92E+01 2.71E+03 -2.78E+03 1.76E+01 1.26E+03 -1.76E+01 -1.26E+03 1.22E+03 -1.30E+03 4 1.54E+01 2.74E+03 -1.54E+01 -2.74E+03 -3.13E+02 2.43E+03 -3.06E+03 5.69E+00 2.33E+03 -5.69E+00 -2.33E+03 2.02E+03 -2.65E+03

44 6 -2.88E+00 -2.36E+03 2.88E+00 2.36E+03 -3.14E+02 2.05E+03 -2.67E+03 4.12E+00 -2.74E+03 -4.12E+00 2.74E+03 2.43E+03 -3.06E+03 7 2.88E+00 -2.74E+03 -2.88E+00 2.74E+03 -3.74E+01 2.70E+03 -2.78E+03 1.16E+01 1.28E+03 -1.16E+01 -1.28E+03 1.24E+03 -1.31E+03 8 3.04E+01 1.02E+01 -3.04E+01 -1.02E+01 9.03E-01 3.13E+01 -2.95E+01 -9.20E-01 -3.19E+00 9.20E-01 3.19E+00 4.10E+00 -2.29E+00 9 -3.45E+00 -3.19E+00 3.45E+00 3.19E+00 7.68E-01 4.22E+00 -2.68E+00 -3.44E+01 -2.49E+01 3.44E+01 2.49E+01 3.52E+01 -3.36E+01 10 3.40E+01 -1.01E+01 -3.40E+01 1.01E+01 -1.27E+00 3.28E+01 -3.53E+01 9.05E+00 -2.94E+01 -9.05E+00 2.94E+01 2.81E+01 -3.06E+01 11 6.15E+00 -2.94E+01 -6.15E+00 2.94E+01 -1.37E+00 2.80E+01 -3.07E+01 -1.84E+01 -3.50E+01 1.84E+01 3.50E+01 3.37E+01 -3.64E+01 12 -3.99E+01 6.47E+03 3.99E+01 -6.47E+03 -1.17E+02 6.35E+03 -6.58E+03 -2.44E+01 5.81E+03 2.44E+01 -5.81E+03 5.69E+03 -5.93E+03 13 3.01E+01 6.44E+03 -3.01E+01 -6.44E+03 -1.12E+02 6.33E+03 -6.55E+03 3.23E+01 5.78E+03 -3.23E+01 -5.78E+03 5.67E+03 -5.89E+03 14 2.37E+01 2.37E+03 -2.37E+01 -2.37E+03 -3.12E+02 2.05E+03 -2.68E+03 -3.10E+01 -1.65E+01 3.10E+01 1.65E+01 -2.81E+02 -3.43E+02 15 1.54E+01 2.33E+03 -1.54E+01 -2.33E+03 -3.14E+02 2.01E+03 -2.64E+03 -2.86E+01 1.65E+01 2.86E+01 -1.65E+01 -2.86E+02 -3.43E+02 16 1.17E+01 7.92E+02 -1.17E+01 -7.92E+02 6.15E+01 8.53E+02 -7.30E+02 2.06E+01 7.08E+01 -2.06E+01 -7.08E+01 1.32E+02 -9.27E+00 17 1.03E+01 -1.29E+00 -1.03E+01 1.29E+00 -1.15E-01 1.02E+01 -1.04E+01 -3.03E+01 -3.25E+00 3.03E+01 3.25E+00 3.02E+01 -3.04E+01 18 -3.55E+00 -3.24E+01 3.55E+00 3.24E+01 -1.36E-01 3.23E+01 -3.25E+01 -4.04E+00 -2.41E+01 4.04E+00 2.41E+01 2.40E+01 -2.42E+01 19 -9.91E+00 1.29E+00 9.91E+00 -1.29E+00 8.42E-02 1.00E+01 -9.83E+00 3.07E+01 -4.88E+00 -3.07E+01 4.88E+00 3.08E+01 -3.06E+01 20 -6.02E+00 -2.41E+01 6.02E+00 2.41E+01 1.45E-01 2.42E+01 -2.40E+01 -6.51E+00 -3.23E+01 6.51E+00 3.23E+01 3.25E+01 -3.22E+01 21 8.94E+00 -7.92E+02 -8.94E+00 7.92E+02 -3.34E+01 7.58E+02 -8.25E+02 3.65E-01 1.24E+03 -3.65E-01 -1.24E+03 1.20E+03 -1.27E+03 22 -1.30E+01 -7.85E+02 1.30E+01 7.85E+02 -3.43E+01 7.51E+02 -8.20E+02 -8.85E+00 1.24E+03 8.85E+00 -1.24E+03 1.21E+03 -1.28E+03 23 -2.20E+01 -7.23E+01 2.20E+01 7.23E+01 0 7.23E+01 -7.23E+01 3.31E+01 -5.37E+01 -3.31E+01 5.37E+01 5.37E+01 -5.37E+01 26 -1.72E+01 -7.15E+01 1.72E+01 7.15E+01 6.09E+01 1.32E+02 -1.06E+01 -1.30E+01 -7.85E+02 1.30E+01 7.85E+02 8.46E+02 -7.24E+02 29 -1.70E+02 -2.21E+03 1.70E+02 2.21E+03 2.41E+01 2.23E+03 -2.18E+03 -1.24E+02 -1.44E+03 1.24E+02 1.44E+03 1.47E+03 -1.42E+03 30 -1.25E+02 -1.44E+03 1.25E+02 1.44E+03 3.81E+01 1.48E+03 -1.41E+03 -7.97E+01 -7.84E+02 7.97E+01 7.84E+02 8.22E+02 -7.46E+02 31 -7.38E+01 -7.84E+02 7.38E+01 7.84E+02 4.97E+01 8.33E+02 -7.34E+02 -2.85E+01 -2.69E+02 2.85E+01 2.69E+02 3.19E+02 -2.19E+02 32 -1.93E+01 -2.69E+02 1.93E+01 2.69E+02 5.80E+01 3.27E+02 -2.11E+02 2.60E+01 6.68E+01 -2.60E+01 -6.68E+01 1.25E+02 -8.76E+00 33 1.61E+02 -2.24E+03 -1.61E+02 2.24E+03 2.43E+01 2.26E+03 -2.21E+03 1.15E+02 -1.46E+03 -1.15E+02 1.46E+03 1.49E+03 -1.44E+03 34 1.17E+02 -1.46E+03 -1.17E+02 1.46E+03 3.85E+01 1.50E+03 -1.42E+03 7.17E+01 -7.95E+02 -7.17E+01 7.95E+02 8.33E+02 -7.56E+02

45 35 6.73E+01 -7.95E+02 -6.73E+01 7.95E+02 5.02E+01 8.45E+02 -7.44E+02 2.20E+01 -2.74E+02 -2.20E+01 2.74E+02 3.24E+02 -2.24E+02 36 1.48E+01 -2.74E+02 -1.48E+01 2.74E+02 5.87E+01 3.33E+02 -2.15E+02 -3.06E+01 6.53E+01 3.06E+01 -6.53E+01 1.24E+02 -6.63E+00 50 -1.01E+01 1.27E+03 1.01E+01 -1.27E+03 -4.00E+01 1.23E+03 -1.31E+03 -8.44E+00 7.68E+03 8.44E+00 -7.68E+03 7.64E+03 -7.72E+03 51 -8.44E+00 7.68E+03 8.44E+00 -7.68E+03 -1.16E+02 7.56E+03 -7.80E+03 -6.75E+00 6.45E+03 6.75E+00 -6.45E+03 6.34E+03 -6.57E+03 52 -1.89E+01 1.26E+03 1.89E+01 -1.26E+03 -3.66E+01 1.23E+03 -1.30E+03 1.23E+01 7.68E+03 -1.23E+01 -7.68E+03 7.64E+03 -7.72E+03 53 1.23E+01 7.68E+03 -1.23E+01 -7.68E+03 -1.13E+02 7.57E+03 -7.79E+03 4.36E+01 6.45E+03 -4.36E+01 -6.45E+03 6.34E+03 -6.57E+03 54 -8.57E+01 1.25E+03 8.57E+01 -1.25E+03 -1.16E+02 1.13E+03 -1.36E+03 -6.52E+01 9.10E+02 6.52E+01 -9.10E+02 7.94E+02 -1.03E+03 55 -6.52E+01 9.10E+02 6.52E+01 -9.10E+02 -7.19E+01 8.38E+02 -9.82E+02 -3.71E+00 -3.60E+03 3.71E+00 3.60E+03 3.52E+03 -3.67E+03 56 1.36E+02 1.21E+03 -1.36E+02 -1.21E+03 -1.13E+02 1.09E+03 -1.32E+03 9.24E+01 9.15E+02 -9.24E+01 -9.15E+02 8.01E+02 -1.03E+03 57 9.24E+01 9.15E+02 -9.24E+01 -9.15E+02 -6.96E+01 8.45E+02 -9.84E+02 -3.94E+01 -3.54E+03 3.94E+01 3.54E+03 3.47E+03 -3.61E+03

Table H.1: FEA output data.

APPENDIX I: BILL OF MATERIALS

Cost Qty. Part Manufacturer (total) 4 1" OD x 1/8" wall Aluminum Tubing (12 ft. section) Alro $122.00 2 1 1/4" OD x 1/4" wall Aluminum Tubing (3 ft. section) Asap Source $60.00 1 3/4" OD x 1/8" wall Aluminum Tubing (3 ft. section) Alro $12.14 1 1/4" x 12" x 24" Aluminum Plate Asap Source $52.92 1 1/4" x 2" x 36" Aluminum Plate Asap Source $10.00 1 1/8" round Aluminum (3 ft. section) Asap Source $2.00 1 26x2.1" Off Road Rear Wheels Sport Aid $299.00

46 1 6" x 1 1/4" Pneumatic Caster Sport Aid $59.00 1 12" x 1 1/4" Scooter Wheel EBAY $10.00 2 5" slotted Aluminum Caster Fork Sport Aid $60.00 4 5/16" Caster Bearings Sport Aid $20.00 1 1/2" diameter X 4 5/8" length Quick Release Axle Sport Aid $55.00 2 1/2" diameter Quickie Axle Sleeve Sport Aid $35.00 4 3/4" x 16 Quickie Axle Sleeve Nut Sport Aid $4.40 2 1" travel Shocks EBAY $57.00 2 JMX-8 Rod Ends for Trailing Arm FK $40.00 1 30' Seat Belt Material General Motors $150.00 6 Caster Fork Bearings Sport Aid $36.00 4 5/16" Plastic Spacers ME Shop $0.00 3 3" x 5/16-18 Bolts Home Depot $2.00 4 1.5" x 5/16-18 Bolts Home Depot $3.00 4 5/16-18 Lock Nuts Home Depot $3.00 3 5" x 1/2-13 Bolts Home Depot $3.00 3 1/2-13 Lock Nuts Home Depot $4.00 2 Wheel Chair Brakes UM Hospital $0.00 20 1/8 Short Pop Rivets Home Depot $10.00 2 Roll of Hockey Tape College Shoe Repair $6.00 1 Box 10-32 x 1.5" Home Depot $5.00 8 0.5 ID .75" OD Nylon Spacers Home Depot $4.00 4 8-32 x .75" bolts Home Depot $1.00 4 8-32 washers Home Depot $1.00 1 1/4" Plywood Home Depot $10.00 1 7/16" Plywood Home Depot $10.00 2 2" x 4" Pine Board (8 ft. section) Home Depot $10.00 2 lbs 2 1/2" Wood Screws Crown Bolt $10.00 2 cans Orange Spray Paint Rustoleum $6.00 1 can Grey Primer America's Finest $4.00 2 cans Clear Coat Rustoleum $6.00

Table I.1: Complete bill of materials.

APPENDIX J: MANUFACTURING DRAWINGS

47 Fig. J.1: Part A, two pieces required.

Fig. J.2: Part B, two pieces required.

48 Fig. J.3: Parts C and N, two pieces required of each.

49 Fig. J.4: Part D, two pieces required. Tubing is 1.25” OD.

50 Fig. J.5: Part E, two pieces required.

Fig. J.6: Part F, one piece required.

51 Fig. J.7: Part G, two pieces required of 1” OD.

Fig. J.8: Part H, two pieces required.

52 Fig. J.9: Part I, two pieces required.

Fig. J.10: Part J, one piece required.

53 Fig. J.11: Part K, two pieces required.

Fig. J.12: Part L, one piece required.

54 Fig. J.13: Part M, two pieces required.

Fig. J.14: Part N, two pieces required.

55 Fig. J.15: Arm rest and shock plate locations.

56 Fig. J.16: Seat back assembly.

57 Fig. J.17: Fifth wheel caster fork sides, two pieces required.

58 Fig. J.18: Fifth wheel castor fork top, one piece required. Construct from eighth inch aluminum plating.