What is the function of a gearbox in power transmission?

The function of a gearbox in power transmission is to change the speed and torque of the output rotational motion. A gearbox is designed to adjust the output speed and torque to meet the requirements of various applications effectively. By doing this, a gearbox allows an engine or motor to operate at its most efficient speed while delivering the necessary power to the driven machinery.

For instance, in many mechanical systems, a high motor speed may need to be converted to a lower output speed with higher torque to drive heavy equipment or machinery. The various gears within the gearbox enable this transformation by either increasing torque at the expense of speed (step-down gear) or increasing speed at the expense of torque (step-up gear). This versatility makes gearboxes crucial components in power transmission systems.

Other options don't align with the primary role of gearboxes. The first option suggests a linear motion, which is not a function of gearboxes primarily involved in rotational aspects. The third option concerning combining energy sources does not pertain directly to how gearboxes function. Lastly, the idea of storing energy for future use implies functions of accumulators or flywheels, which are distinctly different from the purpose of gearboxes.