What is the main purpose of a reduction gear in machinery?

The main purpose of a reduction gear in machinery is to decrease speed while increasing torque. This mechanical system is designed to take rotational energy from a motor, which typically operates at a high speed and lower torque, and convert it into a lower speed and higher torque output. This transformation is crucial in applications where high torque is needed to perform work, such as in heavy machinery, vehicles, and various industrial equipment.

By reducing the speed of the output shaft, the reduction gear allows for greater force to be applied to the task at hand, making it essential for effective performance in scenarios that require substantial power. This functionality is particularly beneficial in applications like cranes, elevators, and trains, where lifting or moving heavy loads is necessary.

The other options do not accurately reflect the primary function of a reduction gear, as increasing speed while lowering torque, synchronizing motor performance, and providing electrical insulation are not the intended purposes of this mechanical component.