LinkageLab

Crank-Rocker

Crank AB rotates fully; rocker CD oscillates. Coupler point traces a closed curve.

crank

coupler

rocker

trace

Mechanism

Geometry

Drag pivots A & D on canvas. Drag the coupler point P to retarget the trace.

Drive

speed ω1.20

View

Live readout

crank L₁— coupler L₂— rocker L₃— ground L₄— s+l— p+q— trans. angle μ— coupler P—

About

Real planar 4-bar position analysis (circle–circle intersection, Grashof's theorem, transmission angle μ). The Jansen leg uses the original 13 link lengths from Theo Jansen's strandbeest. Watt & Chebyshev presets place the coupler tracking point so that the central portion of its curve lies on a near-perfect straight line.