« Back to Dictionary Index

Arc of Recess

The arc of recess is the segment of the pitch circle of a gearwheel over which two teeth are in contact while moving away from the pitch point.


  1. Gear Mechanics:
  • Pitch Circle:
    • An imaginary circle that rolls without slipping with a pitch circle of a mating gear.
  • Arc of Recess:
    • The part of the pitch circle where two gear teeth remain in contact as they move away from the pitch point until they disengage.
  1. Components:
  • Pitch Point:
    • The point on the pitch circle where two gear teeth are exactly aligned with each other.
  • Arc of Contact:
    • Encompasses both the arc of approach (engagement) and the arc of recess (disengagement).
  1. Importance:
  • Smooth Disengagement:
  • Load Distribution:
    • Helps distribute the load over multiple teeth during the disengagement phase, reducing stress on individual teeth.
  • Efficiency:
    • Reduces noise and wear during the disengagement process, contributing to the overall efficiency of the gear system.
  1. Design Considerations:
  • Tooth Profile:
    • Teeth should be designed to ensure a smooth arc of recess for effective load distribution and minimal wear.
  • Gear Ratio:
    • Affects the length of the arc of recess. Proper design ensures the gear teeth have optimal contact during disengagement.
  • Material and Lubrication:
    • Selecting appropriate materials and lubrication helps minimize wear during the arc of recess.

Understanding the arc of recess is crucial for designing durable and efficient gear systems. It ensures that gears disengage smoothly, distribute loads effectively, and minimize wear and tear, leading to longer-lasting and quieter gear operations.

« Back to Dictionary Index