A cam mechanism is a profiled shape (similar to the one shown on the right) mounted on a shaft that is used to convert rotary motion into linear motion - Leaving Cert DCG - Question C-4 - 2022

For the interval from 90° to 120°, the follower remains at the 70mm height without any movement. This should be depicted as a horizontal line at the 70mm mark until the 120° point.

During the segment from 120° to 180°, the follower falls 20mm uniformly. This will appear as a straight line descending from the 70mm line to the 50mm line, ending at the mark corresponding to 180°.

In this interval, the follower falls further down 50mm with simple harmonic motion. The graph should show a curve, starting at the 50mm mark at 180° and reaching the 0mm mark at 360°. The curvature can be approximated to represent the characteristics of simple harmonic motion.

Begin by drawing a rectangle to represent the elevation of the cylinder, with dimensions that correspond to its height of 120 mm. The plan view can be depicted as a circle drawn to scale, representing the top face of the cylinder.

From the plan view, mark a point representing the start of the helix and project lines upward to indicate the height of the helix. As you progress along the helix, ensure to maintain uniform spacing to reflect the regularity of the helical path.

In the elevation view, make sure to mark the ends of the helix on the cylinder’s side accurately. Use the projections to define the points along the height and curve of the helix.

Between points A and B, sketch the helix in elevation. Ensure it wraps around in an anticlockwise direction as it ascends from the base point A to the top point B.