Which gear type allows adjustments in speed and torque without altering direction?

The internal spur gear is characterized by its ability to provide changes in speed and torque while maintaining the same direction of rotation. This is particularly beneficial in applications where consistent output direction is critical, such as in various types of machinery and transmission systems.

Internal spur gears are designed with teeth that are cut on the inside of a cylindrical surface, allowing them to mesh with external gears or with other internal gears in a multi-gear arrangement. By adjusting the size of the gears (the pitch diameter), one can effectively modify the torque and speed ratios. When a smaller internal spur gear drives a larger one, the output speed decreases while the torque increases, and vice versa, all without changing the rotational direction.

This distinguishes internal spur gears from other gear types, which either change the direction of rotation, like bevel gears, or have limitations in terms of speed and torque adjustments without affecting the output direction. Thus, the internal spur gear is a versatile choice for engineers needing controlled changes in speed and torque in a linear and straightforward manner.