http://www.sdsu-cav.com
Project Team: Mitchell Greene, Stephanie Jacobs, Betty Jo, Marshall Noble, Adam York Advisor: Ken Gamble
INTRODUCTION
As part of the Mechanical Engineering program at San Diego State University, it is
required that all students enroll and complete ME490, but what exactly is this
educational course? ME490 is a year long (two semester) course broken down into
two separate courses: ME 490A and ME490B. The overall objective of the course
is to apply the engineering principles and the design techniques learned in prior
course work to a “real world” engineering-like setting. More specifically, these
techniques and principles will be utilized in designing, building, and testing of an
engineering system. A single project is completed in this two-course sequenced and
is judged on the presentation of an oral and written report. In addition, issues
related to ethics and engineering practice are discussed.
Our team consists of five Mechanical Engineering Students: Marshall Noble,
Mitchell Greene, Betty Jo, Stephanie Jacobs and Adam York along with our
From Left to Right: Adam York, Brian Brink, Betty Jo, Mitchell faculty advisor Ken Gamble. Our ultimate Goal is to use compressed air as a fuel
Greene, Marshall Noble. (NOT PICTURED): Stephanie Jacobs source to power a light weight vehicle.
DESIGN SPECIFICATIONS DESIGN CONCEPT
Our first concept of this project was to use the golf cart as our vehicle and take out
•Maximum speed of 10 MPH
the electric motor where the differential is located. The existing differential is
•Driving Range of 9 holes of golf (Approx. 2 Miles) attached to the rear axle. In order to drive the differential we would need a coupler
that meshes with the existing spline. The electrical motor has a shaft and coupler
•Decrease Overall Golf Cart Weight
that was once attached to the gear of the differential. Our team decided to re-use this
coupler. We decided to have the shaft as an adapter for our air motor to the
FINAL DESIGN & ASSEMBLY differential. We used a hydraulic press machine in order to press out the shaft and
coupler that was inside of the electric motor. The air motor acquired for the project
is small enough to be directly mounted to the existing differential. To do this a
mounting plate was fabricated out of two steel plates, one which would be directly
bolted to the motor, the other directly bolted to the differential. A Chromoly Steel
tube would be present in between the two steel plates to house the shaft and the
coupler.
Shaft & Coupling Spline from Electric Motor
TOP LEFT: Exploded View of Assembly in SOLIDWORKS
TOP RIGHT: Assembly in SOLIDWORKS
Schematic of air line and pneumatic component assembly
BOTTOM: Fabricated Assembly in existing differential
TESTING & RESULTS
Pred. P N ω V V Nmotor
SPEED TESTING PROCEDURE PSI PSI RPM Rad/s Ft/s MPH Rad/s
1. Affix reflective tape on the wheel as your point of reference
30 50 196.6 20.59 15 11 2,446
2. Point the Stroboscope Tachometer beam toward the reflective
tape. 25 60 199.9 20.93 16 11 2,487
3. Use adjustment knob to adjust the rate of the strobe flashes 30 70 277.9 29.10 22 15 3,457
until it appears that the point of reference is no longer moving.
50 80 291.0 30.47 23 16 3,620
4. Read and Record the RPM value on the Stroboscope’s LED
display. 55 90 317.0 33.20 25 17 3,943
5. Use RPM values to calculate the “free” traveling speed. 60 100 329.4 34.49 26 18 4,098
ACKNOWLEDGEMENTS
We would like to thank the following companies for their continued support and contributions to our project.