The document summarizes the design of a planetary gear transmission for a Baja SAE vehicle. It outlines the project background, constraints, and design process. The transmission uses a planetary gear system to achieve forward, neutral, and reverse with a 7:1 gear ratio in a compact design. Team members presented on the gear and shifting systems, transmission box, shafts, bearings, and safety analysis. Testing showed gear ratios of 6.56:1 for speed and 3.79:1 for torque. The basic functioning design demonstrates the feasibility of a lighter, more efficient planetary transmission for the competition.

1. Planetary Gear Transmission
Final Presentation
May 27, 2016
Team Members: Joel Huerta
Miguel Avila
Jonathan Villamor
Richie Aunchareonpornpat
SAE BAJA Liaison: Kevin Knarr
Faculty Advisor: Ted Nye
California State University, Los Angeles

2. AGENDA
2
1. Background and Programmatics Joel
2. Design Options, Planetary Gear System, and Shifting Miguel
3. Transmission Box, Bearings, and Shafts Jonathan
4. Bolts, Screws, and Margin of Safety Richie
5. Design Challenges, Mechanical Assembly, and Conclusion Joel

3. WHAT IS BAJA?
• Annual Competition
by Society of
Automotive Engineers
• Small off-road cars
that can withstand
harsh terrain
• Judged based on
various events (Hill
Climbs, Rock Crawls,
Endurance Race, etc.)
3

4. PROJECT BACKGROUND
• All teams are given the same engine
• A lighter, smaller, and more efficient gearbox would help the team
become more competitive
• A set up using a planetary gear system was proposed as a way to satisfy
all three requirements
4
Current System Proposed System

5. SCOPE
• Design and analyze a
prototype gearbox
• Provide a more efficient and
lighter planetary gearbox
• Investigate if a more efficient
gear ratio reduction in a
more compact volume is
reasonable
5

6. ORGANIZATION CHART DEFINED PROJECT
RESPONSIBILITIES
6
Student Lead
Joel Huerta
Technical
Review
Theodore Nye
Project Review
Authority
Kevin Knarr
Design of Gear and
Shifting Systems
Miguel Avila
Gear Box and Overview
Richie A. and Joel Huerta
Shaft and Bearing
Analysis
Jonathan Villamor

7. PROJECT CONSTRAINTS WERE MET
WITH SCHEDULE
7
WBS 4 11 18 25 1 8 15 22 29 6 13 20 27 3 10 17 24 31 7 14 21 28 6 13 20 27 3 10 17 24 1 8 15 22 29 5 12 19 26
1 ProgramMilestons SRR/CoDR PDR Deliver CDR/Expo
1.1 ProgramKeyEvents OrderParts Receive Parts Baja Competition
1.2 Phase 1-Requirements andConcept Design
1.3 TransmissionRequirements
1.4 Reviews
2 Phase 2-Detail DesignandFabrication
2.1 Designof Transmission
2.2 Analysis of Transmission
2.3 Concept Designof TransmissionBox
Select Appropriate Shaft Lengths and Diameters
2.4 Stress and LoadingAnalysis of Gears
2.5 Stress and LoadingAnalysis of Shafts and Sizingof Bearings
2.6 Designof Prototype
3 Phase 3-Final AssemblyandEvaluation
3.1 Fabricationof Prototype
3.2 Assemblyof Gear Box
3.3 Testingof Gear Box
3.4 Evaluationof Output Gear Ratio
3.5 Failure Modes and Effects Analysis
4 ProgramManagement
4.1 WeeklyMeetings Agendas and Minutes
4.2 OralPresentationand WrittenReport
4.3 Reviews
Nov
FallQuarter2015
Dec Jan
Activity
Apr May JuneOct
WinterQuarter2016 SpringQuarter2016
MarFeb

8. PROJECT CONSTRAINTS DEFINED BY REQUIREMENTS
8
No. Requirement Name Performance Objective Capabilities
1 Gear Ratio 7:1 7.01:1
2 Weight <39lbs 51 lbs
3 Volume 4 in. x 12 in. x 8 in. 6.41 in.x 15.05 in. x 10.16 in.
4 Transmission Modes Forward, Neutral, Reverse Forward, Neutral, Reverse
5 Max Continuous Torque >42 lb-ft 180.28 lb-ft
6 Max Shock Torque >293.02 lb-ft 306.37 lb-ft
7 Moisture Environment Sealed Gearbox and Bearings Comply
8 Interface Shall Meet MICD Non Compliant

9. AGENDA
9
1. Background and Programmatics Joel
2. Design Options, Planetary Gear System, and Shifting Miguel
3. Transmission Box, Bearings, and Shafts Jonathan
4. Bolts, Screws, and Margin of Safety Richie
5. Design Challenges, Mechanical Assembly, and Conclusion Joel

10. CONCEPT DESIGN OPTIONS
10
Design 2Design 1 Design 3
• Most Efficient
• Heaviest Design
• Hard to achieve reverse
• Expensive Ring Gear
• Lightest Design
• Spur Gears Easy to Design

11. PLANETARY GEAR SYSTEM
• Forward, neutral, and reverse were
obtained
• Gear system still needs to be optimized
for mass
11

12. GEAR TEETH DETAILS
12
Output Spur Gear: 68
Ring Gear: 46 Planet Gears:16
Sun Gear:14
Carrier Spur
Gear: 42
Idler Input
Gear: 18
Output Idler
Gear: 25 Output spur gear:
1.0 inch
Planetary system:
1.1 inch
Idler gear:
1.0 inch
Carrier spur gear:
1.0 inch
Reverse gear:
1.0 inch

13. GEAR RATIOS BETWEEN GEARS
13
Output forward gear
ratio: 7.01
Output reverse gear
ratio: 4.96
Gear ratio of planetary
system: 4.34
Equation used for
Planetary Gear Analysis:

14. SHIFTER DESIGN MODES
14
Forward
7.01:1
Neutral
Reverse
4.96:1

15. SHIFTER DESIGN
15

16. AGENDA
16
1. Background and Programmatics Joel
2. Design Options, Planetary Gear System, and Shifting Miguel
3. Transmission Box, Bearings, and Shafts Jonathan
4. Bolts, Screws, and Margin of Safety Richie
5. Design Challenges, Mechanical Assembly, and Conclusion Joel

17. TRANSMISSION BOX
17
*Transmission Box Material is Aluminum Alloy 2024 T-4
Dimensions are in inches.
6.41
10.16

18. SHAFTS AND BEARINGS
18
BearingsShafts

19. 19
Shaft Bearing # Bore Dynamic Load Static Load Material Margin of
Safety
Input 7206-2RS 1.1811 in 4,875 lbs. 3,165 lbs. 52100
Chrome
Steel
0.98
Output 7206-2RS 1.1811 in 3,435 lbs. 2,020 lbs. 52100
Chrome
Steel
1.58
Idler 7205-2RS 0.9842 in 4,875 lbs. 3,165 lbs. 52100
Chrome
Steel
1.31
BEARING ANALYSIS
Ball Bearing : 𝐿10
𝐶
𝑃
3

20. SHAFT ANALYSIS
20
Shaft Length Diameter Margin of
safety
Input 8.44 in. 1.18 in. 1.32
Output 10.41 in. 1.18 in. 1.50
Idler 6.41 in. 0.98 in. 2.01
𝑑=
32 𝑁 𝑓
𝜋
𝑘 𝑓
𝑀 𝑎
𝑆 𝑓
2
+
3
4
𝑇 𝑚
𝑆 𝑦
2
1/2 1/3
*Factor of Safety Factor Assumption, N=1.1

21. AGENDA
21
1. Background and Programmatics Joel
2. Design Options, Planetary Gear System, and Shifting Miguel
3. Transmission Box, Bearings, and Shafts Jonathan
4. Bolts, Screws, and Margin of Safety Richie
5. Design Challenges, Mechanical Assembly, and Conclusion Joel

22. BOLTS AND SCREWS
22
Bolts Screws

23. MARGIN OF SAFETY TABLE
Face
Width
Number
of Teeth
Bending
Stress
Margin of
Safety
Gear F (in) N σb (psi) Bending
Sun 1.1 14 74749.15 0.37
Planet 1.1 16 76410.24 0.34
Ring 1.1 46 44082.83 1.32
Carrier 1 42 83913.81 0.22
Idler 1 18 25923.03 2.94
Reverse 1 25 81228.26 0.26
Output 1 68 94766.31 0.08
Margin of Safety:
𝑀𝑆 =
𝜎 𝑦
𝜎 𝑝𝑟𝑒𝑑
′
∗ 𝑁
− 1
*Factor of Safety Factor
Assumption, N=1.1
Bending Endurance Strength (SFB)=112400 psi

24. OLD VS. NEW
24

25. AGENDA
25
1. Background and Programmatics Joel
2. Design Options, Planetary Gear System, and Shifting Miguel
3. Transmission Box, Bearings, and Shafts Jonathan
4. Bolts, Screws, and Margin of Safety Richie
5. Design Challenges, Mechanical Assembly, and Conclusion Joel

26. DESIGN CHALLENGES
26
Fixed Clutch and U-Joint Distance
6.41 inches
Volume Requires Frame
Modifications
(Old Design)

27. PRINTED GEARBOX
27
11.81 in.

28. 3D PRINTED GEARBOX
28

29. GEAR RATIO TESTING AND
SCHEMATIC
Test
Ratio
Obtained
Turn Test 7:1
Speed Test 6.56:1
Torque Test 3.79:1
29
Speed Test
POWER
SOURCE
MOTOR
GEAR
SYSTEM
TACHOMETER
BRAKE
GEAR
SYSTEM
TORQUE
WATCH
SENSOR
TORQUE
TRANSDUCER
MULTIMETER
POWER
SUPPLY
Torque Test

30. SUMMARY AND REVIEW
30
• Forward, neutral, and reverse were achieved by prototype
• 7:1 gear ratio achieved by design
• Basic design shows feasibility, ready for future optimization

31. 31

32. QUESTIONS?