Pushing the pin down allows mechanical engagement to the gears in the lower part of the fan that then connects to the part that rotates the fan body (four part mechanism), while the motor continues to turn the blades. Lift the pin up, no contact, no oscillation, but fan blades continue twirling.
“How a fan rotates.”
Image courtesy of https://imgur.com/gallery/wWzgAtv.
How a fan works! The inner workings behind the cool. ENGR220
March 26, 2012
Oscillation (back and forth turning of fan)
Pin with Circular gear
Four bar mechanism
Spinning motion of gears : Oscillation motion of fan
Circular gears (3)
Motor attached to worm gear
Worm gear attached to circular gear
One circular gear spins : Other circular gears spin
Other circular gears attached to four bar mechanism : Oscillation motion of fan
Along the same lines as, “The toe bone is connected to the heel bone, the heel bone is connected to the foot bone, the foot bone is connected to the ankle bone…”