What is the main purpose of gears or cogs in a mechanical system?

Gears, or cogs, play a fundamental role in mechanical systems primarily by transmitting motion and torque between different components. When gears mesh together, the rotation of one gear causes the adjacent gear to turn as well, allowing for the effective transfer of energy and motion. This capability is essential in applications ranging from simple machinery to complex systems like automotive transmissions and robotics.

Additionally, gears can modify the speed and torque of the output motion relative to the input motion. For example, a larger gear can reduce the speed of rotation while increasing the torque, which is critical in many engineering applications where specific motion characteristics are required.

While some other functions, such as holding components together or making electrical connections, are important in mechanical design, they do not accurately describe the primary function of gears within a system. Gears do not serve tasks related to insulation either, as their design is primarily focused on the mechanical interaction and motion transfer rather than thermal or electrical insulation. Thus, the principal purpose of gears is indeed to transmit motion and torque efficiently within mechanical systems.