1. P08002: Raising the Bars Ryan Hellems Project Lead Justin Knowles ME
Justin Vowles ME
Jeff Osborne ME
Jessica Stalker ISE
Dr. B. DeBartolo Project Advisor
Customer: Nazareth Physical Therapy Clinic, JJ Mowder
Sponsor:
This material is based upon work supported by the National Science Foundation under Award No. BES Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation

2. Project Rationale
The physical therapy clinic at Nazareth uses parallel bars to aid in walking rehabilitation for stroke and other neurological patients.
Peg and pin system is difficult, time consuming, and inaccurate when adjusted.
Redesign needs to simplify raising and lowering of parallel bars, and insuring they remain level.

3. Key high level customer needs
Must be safe
Support patient load without drop (350 lbs)
Stable upright supports
No pinch points or sharp edges
No trip or snag hazards
Accurate height adjustment
Must be easy to use
<9 Lbs force to raise
Reasonable time to adjust (90s)
Bars remain level along full length
Reliable for 5 years of service

4. Current System

5. Selected Concept Selected Concept Existing Parallel Bars
Hand Crank Tower
Lifting System
Drive Shaft w/cover

6. Design Details – Lifting System
Three posts tied-in series by singular drive shaft
1:1 perpendicular miter gears transmit rotation from drive shaft to ACME rod
5/8-8 ACME Rod supports vertical loads, transmits weight to outer post.
ACME nut welded to inner post rides up/down rotating threaded rod

7. Design Details – Hand Crank Tower
4:1 gear ratio for belt drive provides 0.5 inch lift per revolution
Ergonomically located hand crank, easy to turn
Removable handle prevents incidental adjustment

8. Testing & Lessons Learned
ACME Nut Alignment Test
Results: Nuts not square, rod contacts shaft wall
Corners of the acme nut were turned down from the as-built to a standard sized hole.
Half-part chamfer was added to keep the part square to the shaft as it was welded.
Miter Gear Alignment Test
Results: Too much movement of gears, bad mesh
Thrust plates redesigned to tighten some tolerances
Snap rings added to prevent any gear travel
Split ring collars added to restrict motion of drive shaft

9. Testing & Lessons Learned
Ease of Installation Check
Results: Uneven floor, drive shafts not straight, need to calibrate towers to ensure level
Added universal joints with slot for drive shaft length and set screws for angular adjustment
Changed bearing design
Full Extension Deflection Test
Results: Current system better than redesigned at max height
Limit functional max height to 42”
Powder coat inner post
Proposed plastic shim at top of outer post

10. Budget Lifting System - $310.03 Drive Shaft System - $371.30
Hand Crank Tower – $327.04
Powder Coating - $235.00
Misc. Hardware - $80.00
Shipping & Handling – $132.37
Total Cost - $1,455.74

11. Project Evaluation Strengths Easy to use Easy to adjust
central location to adjust both sides; saves walking
Easy to adjust
Low torque requirement - ergonomics
Ability to revert to previous set of parallel bars if design is unacceptable or customer is dissatisfied
16 gauge steel cover to protect against rotating drive shaft
can withstand 250 individual falling or jumping on it
Professional looking – powder coating won’t rust over time

12. Project Evaluation Weaknesses
Lack of safety cover for hand crank tower
exposed belt and sprockets poses pinch point
Lack of height indicator
Sprocket misalignment may cause premature belt wear
Too much deflection from clearance between inner and outer posts

13. Current State Of Design
Design does not meets all customer needs
Lacks height indicator & safety covers for hand crank towers
Design does not current meet all engineering specs
Horizontal deflection is still unknown, close to spec without powder coating, expect better results
Torque to raise needs quantification – passed usability trial
Budget: Below target
Schedule:
Schedule slipped, due to long lead time at powder coaters, delay of assembly and testing
Successful prototype had unrealized flaws
Partial installation scheduled for this afternoon; target completion next week during clinic downtime
Future Improvements
Easy to convert to electric drive in future
Tighter tolerances on posts, looser control of ACME nuts

14. Acknowledgements A special thanks to: Guide: Dr. Beth DeBartolo
Corporate Contact: Nazareth Physical Therapy Clinic
JJ Mowder-Tinney
Lindsey Pendleton
A special thanks to:
Rob Kraynik
Steve Kosciol
Dave Hathaway
Paul Gaylo
Frank Lucisano (welding)
Andrew Cappella (welding)
Dr. Daniel Haines (Manhattan)
Brian Kolenich (Bailey)