Transmission of force and motion between parts
To pass turning motion from one shaft to another, gears and sprockets are used. The most common are cylindrical and bevel (conical) gear drives. When rotation must be turned into straight-line motion, a rack-and-pinion drive is used: a gear meshed with a toothed rack. To carry rotation over a distance, belt or chain drives are used; they consist of two pulleys (or sprockets) and a belt or chain. Belt drives are widely used in drilling, turning and milling machines. A bicycle has a chain drive: the pedal sprocket turns the rear wheel through the chain.
Model: draw two cardboard gears (12 teeth each) and have an adult cut them out; fix them on thick cardboard with paper “axles” (no pins) and turn them. If one gear turns to the right, which way does the other turn? Observe and write. Done without sharp objects.