What is the purpose of a gearbox in a mechanical drive system?

The purpose of a gearbox in a mechanical drive system is to change the speed and torque characteristics of the input from a motor to better match the requirements of the driven equipment. Specifically, when a gearbox reduces the speed of the motor output, it simultaneously increases the torque delivered to the load. This function is essential because many applications require high torque at lower speeds for efficient operation, such as in industrial machinery, vehicles, and various equipment that need to handle heavy loads.

By using a gearbox, the system can achieve the desired balance between speed and torque, allowing the motor to operate within its optimal range while effectively driving the connected load. This makes the gearbox a critical component in various mechanical systems where power transmission is needed under specific conditions.

Other options are less relevant to the function of a gearbox. While maintaining a constant speed may be important in some applications, it is not the primary purpose of what a gearbox does. Likewise, aligning the motor and load does not capture the essence of torque and speed modification provided by a gearbox, nor does increasing speed without the corresponding torque increase align with the mechanical principles that gearboxes are designed to manage.