An internal gear, also known as an internal ring gear or inner gear, is a specialized type of gear transmission device. Unlike conventional gears, the design and functionality of an internal gear differ. Its teeth are located on the inside, engaging with an external gear or gear rack, creating a gear transmission system.

Internal gears are commonly used in ring gear transmission systems, such as planetary gear drives and worm gear drives. Their unique design allows them to provide high gear ratios and achieve the conversion of rotational motion to rotational motion.

Key characteristics of internal gears include:

Internal Teeth: Unlike conventional gears, the teeth of internal gears are located on the inside, engaging with an external gear or gear rack.

High Gear Ratio: Internal gears are often used in applications that require high gear ratios, enabling high-speed reduction or increased torque.

Smooth Transmission: The continuous distribution of teeth in internal gears ensures smooth transmission, reducing vibrations and noise.

Complex Manufacturing: The presence of internal teeth in internal gears makes their manufacturing and assembly relatively complex, requiring a high level of engineering expertise and manufacturing techniques.