Lesson 4: Ackermann Steering Geometry
Duration of Days: 3
Lesson Objective
SWBAT:
Diagram a steering system that follows the Ackermann Principle.
Measure the difference in steering angle between the inside and outside wheels at full lock.
If both wheels turned at the exact same angle, why would the car slow down in a turn?
How does the position of the steering arms (relative to the kingpin) create the Ackermann effect?
Ackermann Principle, Inside Wheel, Outside Wheel, Turning Radius, Slip Angle, Steering Arm.
CT-CTE.MFG.B.07: Apply geometric principles to layout.
DOK Level: 3 (Strategic Thinking)
Students dive into the geometry of turning. The purpose is to understand why the inside wheel must turn at a sharper angle than the outside wheel during a corner to prevent "scrubbing" speed.
Misconception: "Both wheels turn at the same angle."
Correction: Because the inside wheel follows a smaller circle than the outside wheel, it must turn more sharply to avoid sliding.
Support: Use a compass to draw two concentric circles (tracks) and show that they have different diameters.
Extension: Students modify a steering arm design in CAD to improve the Ackermann percentage of a vehicle.
The Turning Radius Test: Students roll the vehicle through a 90-degree turn and check for skid marks/scuffing from the outside tire.