What is the primary function of gears in mechanical systems?

The primary function of gears in mechanical systems is to transmit rotational effects. Gears are designed to interlock with one another, allowing force and motion to be transmitted from one gear to another. This interaction is essential for transferring energy effectively within machinery, enabling components to work together seamlessly.

When gears are engaged, the motion of one gear drives the motion of another, which can result in changes to speed, torque, and direction of rotation depending on the sizes and arrangement of the gears involved. The transmission of rotational effects is fundamental to many applications, from simple clocks to complex automotive transmissions.

While gears can indeed influence speed and torque, and can also change direction of forces, their main role is to ensure that rotational motion is efficiently passed through the system, which is why "transmit rotational effects" is the correct key function associated with gears.