Question

For the better dynamic performance of cam follower mechanism, the following displacement diagrams should be chosen

• A. Simple harmonic motion
• B. Parabolic motion
• C. Cycloidal motion
• D. Uniform acceleration

Hint:

Cycloidal motion is the preferred choice for high-speed cam applications because its acceleration curve starts and ends at zero. This eliminates sudden acceleration jumps, keeping the jerk curve finite and preventing mechanical shock.

Answer 1

The Correct Option is C

To determine the best displacement diagram for the dynamic performance of a cam-follower mechanism, we consider the type of motion each option provides:

1. Simple Harmonic Motion (SHM): This type of motion is smooth and periodic, characterized by sinusoidal velocity profiles. However, the acceleration is not continuous and can lead to jerks, especially at points of reversal, which can affect dynamic performance.
2. Parabolic Motion: While providing a constant acceleration over certain parts of the motion cycle, parabolic motion may not be ideal as the sudden change in acceleration at start and end points can introduce vibrations and lead to undesirable dynamic behavior.
3. Cycloidal Motion: Cycloidal motion offers the best characteristics for cam-follower systems from a dynamic standpoint. It results in a smooth transition in displacement, velocity, and acceleration. The motion is characterized by continuous acceleration (no abrupt changes), minimizing vibration and shock, which is essential for enhanced dynamic performance.
4. Uniform Acceleration: This motion involves a constant rate of change in velocity. However, similar to parabolic motion, the abrupt start and stop can introduce discontinuities in jerk (the derivative of acceleration), leading to less favorable dynamic characteristics.

Evaluating these options, cycloidal motion is the most suitable choice for ensuring good dynamic performance in cam-follower systems. It minimizes vibration and shock, providing a smoother operation.