Lesson 4: Drive Train Mechanics—Power to the Pavement
Duration of Days: 5
Lesson Objective
SWBAT:
Calculate Gear Ratios to determine the trade-off between acceleration (torque) and top speed.
Align a drive chain and set proper tension to minimize friction and prevent "chain-drop."
Why does a race car need a different gear ratio for a hilly track vs. a flat track?
How does friction in a dirty chain "steal" battery life?
Gear Ratio, Sprocket, Drive Chain, Tensioner, Keyway, Set Screw, Friction, Torque, RPM, Center-to-Center.
CT-CTE.TRANS.B.11: Identify and describe the operation of power train systems.
DOK Level: 2 (Application)
This lesson covers the mechanical side of the drivetrain. The purpose is to understand how the motor’s rotational energy is transferred to the drive wheel via chains, sprockets, and bearings.
Misconception: "The tighter the chain, the better."
Correction: A chain that is too tight causes massive friction and can bend the motor shaft; it needs a specific amount of "slop."
Support: Provide a "Sprocket Calculator" spreadsheet where students can input tooth counts to see resulting speeds.
Extension: Students analyze the "Mechanical Advantage" of the current drivetrain and propose a change for a high-torque hill climb.
Students must align a motor sprocket to a rear wheel sprocket using a laser or straight-edge and justify their tension settings.