Can the ring gear achieve the interchangeability between high speed and low torque and low speed and high torque?

The ring gear itself is a passive mechanical component that mainly transmits force and motion. It cannot achieve active conversion between high-speed low torque and low-speed high torque alone, but it can be used as a part of the gear transmission system to help achieve this exchange throughout the entire mechanism.

The exchange between "high-speed low torque" and "low-speed high torque" that we often refer to is actually a process of changing the mechanical transmission ratio, which is achieved through the gear ratio (i.e. the ratio of teeth between gears). In this transmission system, the ring gear often plays the role of an internal gear or an external gear, and completes the output of different speeds and torques by meshing with other gears such as sun gears, planetary gears, and small gears.

For example, in planetary gear reducers, the ring gear is usually used as a fixed or rotating internal gear, forming a complex transmission relationship with the sun gear and planetary gear. When a high-speed, low torque power source (such as an electric motor) is input and reduced by a gear set (including a ring gear), low-speed, high torque power can be output. On the contrary, if low-speed high torque is input during reverse operation, high-speed low torque can also be output as long as the entire system structure allows for reverse transmission.

Similarly, in the car starting system, the starter small gear operates at high speed and low torque, and drives the engine flywheel to rotate by meshing with the flywheel ring gear. The engine requires a large starting torque due to its large inertia, and the gear ratio of the flywheel ring gear amplifies the torque and reduces the speed.

It should be clarified that the ring gear does not actively generate variable speed and torque functions, it is only a component of the entire gear set. Whether the effective conversion between high-speed low torque and low-speed high torque can be achieved depends on the design of the entire gear system, including tooth ratio, meshing method, and whether multi-stage reduction is used.