[Planetary gear] A planetary gear animation. #manim #animation #geometry #gears #mechanics

20250218_planetary.py

from manim_gearbox import *

class PlanetaryGears(Scene):
    def construct(self):
        # https://en.wikipedia.org/wiki/Epicyclic_gearing#Gear_speed_ratios_of_conventional_epicyclic_gearing
        omegaplanet = 0.44
        omegacarrier = 0.44*10/15
        omegaring = (15+35)/35*omegacarrier
        module = 0.15  # diameter = module * number of teeth

        # Create the sun gear (center gear)
        sun_gear = Gear(
            15, stroke_opacity=0, fill_color=YELLOW, fill_opacity=1, module=module  # 15 teeth
        )

        # Create the ring gear (outer gear)
        ring_gear = Gear(
            35, module=module, inner_teeth=True, stroke_opacity=0, fill_color=RED, fill_opacity=1,
        )

        # Create the planetary gears and position them
        def planetUpdater(mobj,dt):
            mobj.rotate(dt*omegaplanet, about_point=mobj.get_center())
        def carrierUpdater(mobj,dt):
            mobj.rotate(dt*omegacarrier, about_point=mobj.get_center())
        def ringUpdater(mobj,dt):
            mobj.rotate(dt*omegaring, about_point=mobj.get_center())
        ring_gear.add_updater(ringUpdater)
        carrier_frame = VGroup()
        for dir in (LEFT, RIGHT):
            gear = Gear(
                10, stroke_opacity=0, fill_color=BLUE, fill_opacity=1, module=module
            ).next_to(sun_gear, dir)
            gear.add_updater(planetUpdater)

            gear.mesh_to(sun_gear)  # Connect the planet gear to the sun gear
            ring_gear.mesh_to(gear)  # Connect the planet gear to the ring gear

            carrier_frame.add(gear)
        carrier_frame.add_updater(carrierUpdater)
        self.add(sun_gear,ring_gear,carrier_frame)
        self.wait(8)

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