I will focus on the oscillating mechanism within an oscillating fan
The oscillating fan is a simple yet brilliant device. The main goal of the mechanism is to rotate the fan back and forth so that cool air can reach a wider widespread area. This is done with the use of gears and a slider-crank mechanism. The fan can either be stationary or oscillating, depending on the positioning of the gears. Once the pin is pressed down and the gears come in contact with each other, the fan begins to oscillate. This design is useful because there is no need for a separate motor to drive the oscillation. The oscillation is driven by the same motor that drives the blades, however, with a smaller speed and greater torque due to the gear ratios.