Which of the following describes a gear train?

A gear train is best described as a series of gears arranged to transmit motion. This arrangement allows for the transfer of power between different rotating components, changing speed and torque in the process. Gear trains are fundamental in various mechanical systems, including vehicles, machinery, and various types of equipment, where precise control over motion is required.

Gear trains work by meshing the teeth of one gear with those of another, enabling motion to be transferred from the driving gear to the driven gear. The arrangement and size of the gears dictate the characteristics of the output motion, such as speed increase or decrease and changes in direction. This is crucial in applications where a specific movement or force is necessary for proper operation.

While other options describe different mechanical systems, they do not fit the definition of a gear train. Belts and pulleys involve flexible connections rather than rigid interlocking teeth, hydraulic mechanisms rely on fluid movement rather than solid gear interaction, and clutches serve to engage or disengage parts of a system rather than transmit motion through a series of interlocked gears.