In a gearbox, what is a pinion?

• A. The slow-moving rotor in a gearbox
• B. The high-speed rotor(s) in a gearbox/gearset
• C. A type of pump attached to the gearbox
• D. The casing that encloses the gearbox

Answer: (B)

A pinion is defined as the high-speed rotor in a gearbox or gearset. In the context of gear mechanisms, the pinion typically engages with a larger gear (often referred to as a gear wheel or gear ring) to transmit motion and torque. The interaction between the pinion and the larger gear allows for speed reduction or torque multiplication, depending on their sizes and arrangement.

When the pinion rotates, it drives the larger gear, which ultimately produces the desired output speed and torque characteristics crucial for the machinery's efficiency. The correct identification of the pinion as the high-speed rotor is fundamental to understanding how gear systems function in rotating equipment, highlighting its significance in ensuring optimal performance in applications such as gearboxes.