Mechanism examples

These examples are linkages and drives, and their geometry follows from their motion. A linkage is drawn once for every crank angle, either from the circles its links can reach or as a constraint sketch in which the crank angle is a driving dimension, and its positions give the coupler curves, the strokes and the accelerations. A part that the motion cuts, as the disc of a cycloidal drive or the locking disc of a Geneva drive, is the blank minus the cutter in every position.

In this section

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Four-bar linkageA crank-rocker and its coupler curve through 72 positions.

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Hood hingeThree-position synthesis in a constraint sketch, checked against the textbook.

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Jansen linkageThe Strandbeest leg with eleven links on one crank and the foot's flat step.

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Straight-line linkagesWatt, Chebyshev and the exact Peaucellier-Lipkin linkage.

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Geneva driveA quarter turn per revolution, with the locking disc cut by what the wheel sweeps.

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Cycloidal driveThe disc cut by every ring pin at every crank angle.

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Belt drivesThe belt length as one expression, with the pulley and tensioner placed by the solver.

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Drilling a square holeA Reuleaux triangle covers about 98.77 % of the square.

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The haberdasher's puzzleA triangle in four hinged pieces swung by one angle into a square, without collision.

Bicycle tracksOnce around any loop, the tracks of the two wheels enclose areas that differ by exactly πL².

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Ackermann steeringA steering trapezoid in a constraint sketch against the Ackermann condition, and the arm angle that comes closest.

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The slider-crank and the Scotch yokeA piston against a pure cosine: the rod's second harmonic and the accelerations at the top and bottom, from a sketch.

See Examples for the other collections.