Spring 2023 > Shifting Gears

Objectives

1. Understand how to calculate a gear ratio.
2. Gain an understanding of how gears work.
3. Build an intuition of what different gear ratios are best used for.

Announcements

1. Welcome back!
2. Discuss engineering notebook.
3. Discuss Engineering Design Process.

Lesson

1. Calculating Gear Ratios
   • Gear Ratio Formula
   • Speed vs Torque
   • Gear Ratio with 3 or more Gears
   • Discuss gear ratio calculation and how it works in LEGO.
2. Video “Spinning Levers – How a Transmission Works“
3. Lab
   • Build geared vehicle
   • Do a test run
     • Does the reference motor complete one rotation?
     • Do both motors stop turning at the same time?
   • Run five experiments using different gear trains
     • Record results in engineering notebook
4. Group discussion

Extras

Gear examples

These gears are in an exercise the team will use to calculate ratios and determine if speed, torque, or neither one will be increased.

Videos

I like how this old video very clearly explains the concept of how car transmissions switch between different gears to change the amount of power sent to the wheels. The video starts with a lever and explains how a gear is like a whole bunch of levers put together. I hope the team gets a kick out of the old style video!