4 Inversions • Live Kinematics Graphs • IC Engine, Whitworth, Oscillating Cylinder • Practice & Quiz
A slider-crank mechanism is a fundamental single-degree-of-freedom linkage that converts rotary motion into reciprocating linear motion (or vice versa). It consists of four kinematic elements: a crank (rotating link), a connecting rod (coupler), a slider (piston), and the fixed frame. This mechanism is the backbone of internal combustion engines, reciprocating compressors, and many industrial machines.
The kinematics of the slider-crank are governed by the crank radius r, connecting rod length l, and any offset e between the slider path and the crank pivot. For an inline configuration (e=0), the piston displacement is x = r·cos(θ) + √(l² − r²·sin²(θ)), the stroke equals 2r, and dead centres occur at θ=0° (TDC) and θ=180° (BDC).
By fixing different links, the slider-crank produces four distinct inversions. The 1st inversion (frame fixed) is the classic IC engine. The 2nd inversion (crank fixed) gives the Whitworth quick-return mechanism and the rotary engine. The 3rd inversion (connecting rod fixed) produces the oscillating cylinder engine. The 4th inversion (slider fixed) yields the hand pump and bull engine. Each inversion has unique industrial applications.
This simulator provides real-time graphs of piston displacement, velocity, acceleration, and turning moment as functions of crank angle. The connecting rod ratio n = l/r (typically 2.5–5 for engines) significantly affects the shape of these curves. An offset slider-crank introduces asymmetry in the forward and return strokes, quantified by the time ratio.
This tool is designed for mechanical engineering students, automotive engineering learners, and instructors teaching mechanisms and machine theory. Whether you are studying for exams, building intuition about engine kinematics, or demonstrating inversions in a classroom, this simulator provides an interactive, visual approach to mastering the slider-crank mechanism.