1. Design of an Off-Road Front Suspension and Steering System
OFF-ROAD INNOVATIONS
Design of an Off-Road Front Suspension and Steering System
GROUP M2: ANDREW SNELGROVE  CALVIN HOLLOWAY  JEREMY SHEPHERD  KATE PRICE

2. Outline The SAE Baja Competition Problem Definition The Current System
Suspension System Validation
Steering System Validation
Design Methodology
Design Targets
Moving Forward
Management Plan

3. The SAE Baja Competition
The Baja SAE Series is an international competition testing the limits of off-road vehicles designed and built by engineering students from around 100 universities each year.

4. Introduction to SAE Baja Competition
Suspension and Traction

5. Introduction to SAE Baja Competition
Rock Crawl
Mud Pit

6. Introduction to SAE Baja Competition
Design Competition

7. Problem Definition
Off-Road Innovations’ goal is to develop a front suspension and steering system for the Memorial Baja team that will:
Provide more driver room
Improve ground clearance
Absorb frontal impact forces
Maintain safety, reliability and low weight

8. 2013 Memorial Baja Steering
The Previous System
2013 Memorial Baja Steering
2013 Memorial Baja Suspension

9. Steering System Validation
Manual Rack and Pinion
Pro: Lightweight and Robust
Con: More Effort to Steer

10. Steering System Validation
Recirculating Ball Gearbox with Pitman Arm
Pro: Less Effort to Steer
Con: Complicated and no driver feedback

11. Steering System Validation
Electric Power-Assisted
Hydraulic Power-Assisted
Pro: Less Effort to Steer
Con: Complicated and Heavy

12. Steering System Validation
Criteria
Rack and Pinion
Recirculating Ball Gear
Hydraulic Power-Assisted
Electric Power-Assisted
Score
Weighted Score
Cost (0.1) 5 1 4
0.8 2
0.4
Weight (0.2)
1.5
4.5
1.35
0.45
1.2
Manufacturability (0.2)
2.5
0.5
0.1
0.3
Performance (0.35)
0.375
3.5
0.525
Maintenance (0.1)
0.6
0.15
Weighted Total
4.275
3.55
1.625
2.725
Final Selection: Rack and Pinion

13. Suspension System Validation
To validate that the chosen system was the best choice for our application we compared alternatives using a decision matrix. Alternatives considered include:
Swing Arm
Double Wishbone
MacPherson Strut
Trailing Links
Swing Axle Pro: Robust Con: Heavy
Double A-arm Pro: Large Motion Range Con: Complexity

14. Suspension System Validation
Trailing Arms
Pro: Compact
Con: Difficult Mounting
MacPherson Strut Pro: Simplistic Con: Limited Range

15. Suspension System Validation
Criteria
Swing Axle
Double A-arms
MacPherson Strut
Trailing Link
Score
Weighted Score
Cost (0.1) 1
0.1 2
0.2 4
0.4
Durability (0.2)
0.8 5 3
0.6
Weight (0.2)
Manufacturability (0.15)
0.3
0.75
0.15
Performance (0.35)
0.7
1.75
1.05
0.35
Maintenance (0.1)
Weighted Total
4.9
2.95
2.5
Final Selection: Double A-arms

16. Design Methodology

17. Design Methodology
Ackerman Steering
Track
Wheelbase

18. Design Targets Design Parameters Previous Design Clarification Value
Static Camber
-4 deg
Camber Change
-6 deg
Steering Axis Inclination
8 deg
Scrub Radius
30 mm
Static Toe
0 deg
Toe Change (over travel)
Static Caster Angle
3 deg
6 deg
Leans into Turns 
Caster Change (over travel)
Track
1350 mm
Wheel Base
1558 mm
1450 mm
 Improves Handling
Static Ride Height
230 mm
281 mm
Raising Ground Clearance 
Vertical Wheel Travel (Jounce)
152.4 mm
200 mm
Shock Compression
Vertical Wheel Travel (Rebound)
100 mm
Recessional Travel
0mm
51 mm
Absorbs Frontal Impact
Unsprung Weight
16.5 Kg

19. Moving Forward Next steps include: Finalizing geometry
Generating Models
Simulation and FEA

20. Management Plan
To mitigate the risks to driver safety and project completion:
Closely follow SAE standards for the Baja SAE series
Monitoring progress with respect to planned milestones

21. References

22. Questions?
More information is also available at: