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Drivetrain Design
42 Tooth Sprocket Design
High-performance sprocket for electric vehicle power transmission
Overview
Timeframe: 2023
Category: Drivetrain / Mechanical Design
Designed a custom 42-tooth sprocket for the UTFR FSAE EV, hitting the target ratio while staying light and strong for racing loads.
The Problem
Needed a 42T sprocket with smooth engagement, low rotating mass, and enough strength for racing loads; off-the-shelf parts were heavy and wrong ratio.
Constraints
- Fixed 42T, 3.67:1 ratio
- Chain and hub compatibility
- Low rotating mass, CNC friendly, student budget
Technical Approach
- Involute-based tooth geometry for smooth engagement
- Tooth root and hub stress checks to set thickness and fillets
- Web and pocket pattern optimized for mass while staying stiff
- FEA plus CNC-ready drawings for quick manufacture
Tools & Technologies
SOLIDWORKS
Finite Element Analysis
Gear Design
CNC Programming
Material Selection
Mechanical Optimization
Impact & Results
1.2 kg
Final Weight
3.5×
Safety Factor
42
Teeth
Results:
- Lightweight part that kept rotating inertia down
- Smooth power delivery from precise tooth form
- Manufacturing-ready package with validated stresses
Design Philosophy
Remove mass only where analysis says it is safe. Involute teeth, targeted pockets, and validated fillets kept the sprocket light without sacrificing stiffness.
Key Learnings
- Gear fundamentals and stress checks matter even on “simple” parts.
- Manufacturing limits can guide cleaner, faster-to-machine geometry.