Background
Engineering Context
A rover motor spins too quickly and does not provide enough output torque for a wheel or lifting mechanism.
IED Unit 4 | Mission Brief 4.3
Design a 5:1 Gear Reduction
Design a gear system with an overall reduction close to 5:1 and demonstrate the expected speed and torque tradeoff.
Objectives
What You Will Practice
- Calculate gear ratios
- Design single- or multi-stage systems
- Connect ratio to speed and torque
- Build or model a mechanism
Materials
What You Need
- Gear sets or CAD gear models
- Axles and supports
- Calculator
- Tachometer or rotation-count method
- Engineering notebook
Procedure
Instructions
- Review the required input and desired approximate 5:1 reduction.
- Create three possible gear-train layouts and calculate each overall ratio.
- Select a design based on ratio accuracy, part count, size, and direction of rotation.
- Build or model the selected train.
- Mark input and output gears.
- Rotate the input a known number of turns and count output turns.
- Compare measured and calculated ratio.
- Explain the expected effect on output speed and ideal torque.
Requirements
Engineering Requirements
- Target an overall reduction between 4.8:1 and 5.2:1
- Show calculations for three concepts
- Support and align every axle
- Demonstrate rotation without gear skipping
- Compare calculated and measured ratio
Constraints
Constraints & Safety
- Use available gears only
- Do not force mismatched gears
- Ignore friction only when labeling the result as ideal
- Mechanism must fit within the assigned footprint
Deliverables
What You Submit
- Three gear-train sketches
- Ratio calculations
- Selection justification
- Built or CAD mechanism
- Measured ratio data
- Speed/torque explanation
Reflection
Reflection Questions
- Why might measured rotation differ from the calculation?
- What changed when an idler gear was added?
- How would you reverse output direction?
- Where is energy lost in the real system?