Slider-Crank Mechanism

The Slider-Crank Mechanism Simulator is an interactive tool for studying the slider-crank linkage and all four of its kinematic inversions. The slider-crank converts rotary motion into reciprocating linear motion (or vice versa) and is the backbone of internal combustion engines, reciprocating compressors, and many industrial machines.

This simulator covers the complete kinematics: piston stroke, displacement, velocity, and acceleration as functions of crank angle. You can visualise how the connecting rod ratio (n = l/r) affects motion symmetry, explore TDC and BDC dead-centre positions, and study all four inversions including the IC engine, Whitworth quick-return, oscillating cylinder engine, and hand pump.

The simulator opens in Simulate mode with the 1st inversion (classic IC engine) preset. The split canvas shows the animated mechanism on the left and a real-time kinematics graph on the right.

• Use the Crank r and Con-rod l sliders to adjust mechanism geometry.
• The Offset e slider introduces an offset between the slider path and crank pivot for asymmetric configurations.
• Switch between Inversions (1st through 4th) using the inversion tabs.
• Select which Graph to display: displacement x(θ), velocity v(θ), acceleration a(θ), or torque T(θ).
• Load industry-relevant presets like IC Engine, Quick Return, Rotary Engine, and Hand Pump.

In Simulate mode, the left canvas renders the animated slider-crank mechanism with colour-coded links. The crank rotates continuously while the piston (slider) reciprocates along its guide. A connecting rod links the crank pin to the piston.

The right canvas displays live kinematics graphs plotting displacement, velocity, acceleration, or turning moment against crank angle. A tracking crosshair follows the current position on the curve. Readout cards show crank angle θ₂, connecting rod angle φ, displacement x, velocity v, acceleration a, stroke length, connecting rod ratio n, and time ratio.

For offset configurations, the forward and return strokes have different durations, quantified by the time ratio. This asymmetry is exploited in quick-return mechanisms used in shaping and slotting machines.

Switch to Explore to study 12 concepts organised into three categories:

• Basics — Slider-crank anatomy, the four inversions, dead centres (TDC/BDC), stroke calculation, and connecting rod ratio.
• Kinematics — Piston displacement equation, velocity analysis, acceleration analysis, and the effect of finite connecting rod length.
• Design & Applications — IC engine mechanisms, quick-return machines, oscillating cylinder engines, hand pumps, and time ratio calculations.

Each concept includes clear explanations, formulas, and worked examples suitable for engineering education and engineering education.

Practice mode generates random numerical problems on piston displacement, velocity, acceleration, stroke length, and time ratio. Enter your answer and receive immediate feedback with a step-by-step solution for incorrect answers.

Quiz mode tests your knowledge with 5 randomised questions from a pool of 15, mixing multiple-choice and numerical problems. Review all answers after completion.

• Start with the 1st inversion preset (IC Engine) to understand the basic mechanism before exploring other inversions.
• Compare the displacement curves for different connecting rod ratios to see how n = l/r affects motion symmetry.
• Use the offset slider to create asymmetric configurations and observe how the time ratio changes for quick-return applications.
• Switch between graph types to see how displacement, velocity, and acceleration relate to each other as derivatives.
• Remember: stroke = 2r for an inline slider-crank, but offset configurations modify this relationship.
• Use Explore mode as a quick reference for formulas before attempting Practice problems.