Definition

1. Noun:
   • A gear in an epicyclic gear train: A "planet wheel" is a specific component in a mechanical system. It is a gear that rotates around a central gear (called the sun gear) while also rotating on its own axis. It is part of a set that may include other planet wheels and an outer ring gear.

Usage

• The term "planet wheel" is a technical, mechanical engineering term. It is used almost exclusively to describe the components of an epicyclic or planetary gear system.
• It functions as a countable noun (e.g., , ).

Examples

• Noun:
  • The mechanic replaced the damaged planet wheel in the automatic transmission.
  • In this model, the planet wheel meshes with both the sun gear and the ring gear.
  • The design uses four planet wheels for better load distribution.

Advanced Usage

• "Planet gear": This is a more common and completely synonymous term for "planet wheel." In modern engineering contexts, "planet gear" is often preferred.
  • The planet gears are held in place by a carrier.
• The system itself is called a planetary gear set or epicyclic gear train.

Variants and Related Words

• Planet gear (n): A direct synonym for "planet wheel."
• Sun gear (n): The central gear that the planet wheel(s) revolve around.
• Ring gear / Annulus gear (n): The outer, internally-toothed gear that the planet wheel(s) also mesh with.
• Planetary carrier / Carrier (n): The structure that holds the planet wheels and connects them to the output shaft.
• Epicyclic gear train (n): The formal name for the entire gear system containing these components.

Synonyms

• Planet gear
• Planetary pinion (a less common term)

Related Phrases

• Planetary gear set: The complete assembly containing sun gears, planet wheels, and a ring gear.
  • The helicopter's rotor drive uses a complex planetary gear set.

Noun

1. an outer gear that revolves about a central sun gear of an epicyclic train