Two Teeth Spur Gear (205)

grabcad

This unique gear features a special profile based on an idea found at http://507movements.com/mm_205.html. It consists of a small pinion and a large gear rim, where the pinion has only two teeth instead of the minimum 14 typically found in involute gears. The gear rim has 22 polygonal teeth placed alternately on the disc faces, resulting in a transmission ratio of 1/11. This same ratio can also be achieved using a regular gear with 14/154 teeth or a worm gear with one thread and an 11-toothed wheel. The pinion's tooth profile is an envelope curve (a spline) based on multiple tangents derived from the gear rim tooth side line, which can also be generated as an involute using Inventor's Equation Curve tool. The parametric equations for an involute are modified to x(t)=r(cos t + 1.2 * t sin t) and y(t)=r(sin t - 1.2 * t cos t). The polygonal teeth profiles would need slight adjustments to achieve correct contact between the pinion and gear rim. All parts were created using Inventor 2014, and an animation can be set in Inventor Studio environments. Note that the main axle was initially placed non-symmetrically but has since been corrected.