The difference between the driving gear and the driven gear

The driving gear serves as the actuator, with its rotational speed and torque determining the system’s initial state.

　　Power source

　　The driving gear is directly connected to power sources such as the engine and electric motor, serving as the energy input end.

　　The driven gear receives no direct power input and relies entirely on the tooth‑surface thrust of the driving gear to generate rotation.

　　Sports role

　　The driving gear serves as the actuator, with its rotational speed and torque determining the system’s initial state.

　　The driven gear is the follower, and its motion is forcibly constrained by the driving gear through their meshing engagement.

　　Number of Teeth and Transmission Characteristics

　　In common gear-reduction mechanisms, the driving gear typically has fewer teeth (and a smaller diameter), while the driven gear has more teeth (and a larger diameter), thereby achieving speed reduction and torque multiplication. Conversely, if the driving gear has more teeth than the driven gear, the system produces speed increase and torque reduction.

　　Force analysis

　　The tooth surface of the driving gear bears the primary force that drives the driven gear.

　　The tooth surface of the driven gear is subjected to a reaction force from the driving gear, with equal magnitude and opposite direction.