Before delving into gear design, it is essential to understand the fundamental terminology. This article covers the most important concepts in gear terminology.
Basic Gear Terms
- Main Gear: In a gear pair, the gear with more teeth.
- Pinion Gear: In a gear pair, the gear with fewer teeth.
- Pitch Circle Diameter (PCD): The circle where the gear pair transmits force and motion.
- Number of Teeth on Main Gear (ZG): The number of teeth must be an integer.
- Number of Teeth on Pinion Gear (ZP): If the number of teeth falls below a certain level, interference increases.
- Center Distance (C): The distance between the centers of the main gear and the pinion gear.
Gear Profile and Dimension Terms
- Base Circle: The circle from which the involute curve starts.
- Involute: The curve that forms the gear profile.
- Root Circle: The circle that passes through the gear root.
- Addendum (a): The radial distance from the pitch circle to the top of the tooth.
- Dedendum (d): The radial distance from the pitch circle to the bottom of the tooth.
- Tooth Height: The sum of addendum and dedendum.
- Working Height: The sum of the addendums of two meshing gears.
- Clearance (c): The gap between the top of one gear tooth and the root of the mating gear tooth.
- Backlash: The space left between meshing teeth when one gear is engaged.
Module and Gear Standardization
- Module (M): The pitch circle diameter divided by the number of teeth, measured in mm.
- Diametral Pitch (DP): A value used in AGMA standards instead of module.
- Pressure Angle (Φ): The angle between the line of action and the tangent to the pitch circle.
- Understanding gear terminology correctly ensures precision in design and manufacturing while guaranteeing optimal gear performance. These terms are essential for anyone working with gears.