Center distance
| Symbol | a |
|---|---|
| Unit | mm |
| Attribute-ID | center_distance_predesign |
| Numeric ID | 18025 |
| Value Type | PMTechArray |
In contrast to spur gears, the teeth of helical gears are inclined at a helix angle β with respect to the gear axis.
| β | Helix Angle |
Specification of the helix angle:
- Right-hand leaning external gears: positive
- Left-hand leaning external gears: negative
For internal gears, the signs (+/-) are reversed.
Greater helix angles lead to increased overlap, and therefore usually to lower noise excitation. At the same time, axial forces also generally increase. Typical helix angles for single helical gears range from 8° to 20°.
Helix angles β depending on the standardized normal module are recommended in DIN 3978.