Right-angled bent link 2 has two slots b whose axes are perpendicular to each other. Sliding along these slots are pins c of a diameter equal to the width of the slots. Displacement x of slider 3 equals the square of the displacement of link 1, i.e. x=(1/a)y³ The mechanism can be used as a parabolograph because point B, the centre of pin c of slider 3, traces a parabola.
$1278$LG,MO$