Active learning ideas
Cams and Followers are essential components in mechanical engineering, used to convert rotary motion into precise linear motion. From the valves in a car engine to the complex movements in industrial packaging machines, cams are everywhere. In the DCG syllabus, students learn to design cam profiles based on a required 'displacement diagram,' which maps the follower's movement over time.
Activity 01
Give groups three different displacement diagrams and three physical cam models. Students must analyze the 'slopes' and 'curves' on the diagrams to correctly pair them with the cams, explaining how they identified features like 'dwell' or 'SHM'.
How does a displacement diagram dictate a cam's profile?
Activity 02
Using a simple 'cam kit' or digital simulation, students are given a target motion (e.g., 'rise 40mm with SHM in 180 degrees'). They must draw the cam, cut it out, and test it against a follower to see if it achieves the desired height and timing.
What is the difference between simple harmonic motion and uniform acceleration?
Activity 03
Show a cam profile designed for a point follower. Students individually sketch how the profile would need to change to accommodate a large roller follower. They then pair up to discuss why the 'pitch curve' is different from the 'cam profile'.
How do roller followers affect the cam profile construction?
A few notes on teaching this unit
Watch Out for These Misconceptions
Students often think the cam profile is the same as the displacement diagram wrapped in a circle.
Use a 'cam-tracer' demonstration. Show that while the diagram represents the *follower's* height, the cam's shape must also account for its own base circle and the follower's width. This distinction is best learned by physically tracing a cam's movement.
Confusion between Uniform Velocity and Simple Harmonic Motion.
Use a pendulum to demonstrate SHM (slow at the ends, fast in the middle) versus a conveyor belt for UV (constant speed). Drawing the displacement curves for both side-by-side helps students see the 'S-curve' of SHM versus the straight line of UV.
Methods used in this brief
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