Profile Design & Motion Diagrams • Displacement • Velocity • Acceleration — Simulate • Explore • Practice • Quiz
Cam and follower mechanisms are fundamental components in mechanical engineering used to convert rotational motion into reciprocating (linear) motion. A cam is a rotating or sliding piece of machinery that transmits a desired motion to a follower through direct contact. The follower is the output element that traces the cam profile and moves accordingly — typically in a straight line (translating follower) or along an arc (oscillating follower). These mechanisms are found in internal combustion engines, textile machinery, printing presses, packaging equipment, and automated manufacturing systems.
Cams are classified by their shape and motion. A disc cam (or plate cam) is the most common type, where the cam profile is machined on the face of a rotating disc. A cylindrical cam has a groove cut into a cylinder surface. An eccentric cam is the simplest form — a circular disc mounted off-centre on a shaft, producing simple harmonic follower motion. Followers are classified by the shape of their contact surface: a flat-face follower has a wide, flat contact surface and distributes the contact force over a larger area, reducing wear. A roller follower uses a small roller at the contact point to convert sliding friction into rolling friction, improving efficiency. A knife-edge follower has a sharp point of contact, allowing it to follow complex cam profiles precisely but wearing faster due to high contact stress.
The cam profile is designed based on the desired motion law of the follower. Simple Harmonic Motion (SHM) produces a sinusoidal displacement curve with smooth acceleration but has a discontinuity in acceleration at the start and end of the stroke, causing jerk. The displacement equation is s = (h/2)(1 − cos(πθ/β)), where h is the lift, θ is the cam angle, and β is the rise angle. Uniform velocity gives a linear displacement (s = hθ/β) but produces theoretically infinite acceleration at the transitions, making it unsuitable for high-speed applications without modification. Uniform acceleration and deceleration (parabolic motion) provides constant acceleration in the first half of the stroke and constant deceleration in the second half, with vmax = 2hω/β and amax = 4hω²/β². Cycloidal motion is considered the ideal motion law because it has zero acceleration at both ends of the stroke, eliminating jerk. Its displacement equation is s = h(θ/β − sin(2πθ/β)/(2π)), with vmax = 2hω/β and amax = 2πhω²/β².
The base circle is the smallest circle that can be drawn from the cam centre, tangent to the cam profile. The trace point is the point on the follower (centre of the roller for roller followers, or the contact point for knife-edge followers) whose path defines the pitch curve. The pressure angle is the angle between the direction of the follower motion and the normal to the pitch curve — it should be kept below 30° for translating followers to prevent jamming. Undercutting occurs when the pitch curve has a radius of curvature less than the roller radius, making the cam profile self-intersecting and impossible to manufacture. Increasing the base circle radius reduces both the pressure angle and the risk of undercutting.
In Simulate mode, select a cam type (Eccentric, SHM, Uniform Velocity, Uniform Acceleration, or Cycloidal), set the base circle radius and lift using sliders, choose a follower type, and adjust the RPM. The left side shows the animated cam rotating with the follower moving up and down. The right side displays real-time displacement, velocity, and acceleration diagrams with a moving crosshair showing the current angle. Use presets to load common industrial configurations. Switch to Explore mode to study 12 concepts across Cam Basics, Motion Laws, and Design categories. Practice mode generates calculation problems, and Quiz mode tests your understanding with 5 randomised questions from a pool of 15.