Consider premature and late mesh
| Symbol | - |
|---|---|
| Unit | - |
| Attribute-ID | S_VORZEIT |
| Numeric ID | 3730 |
| Value Type | PMBoolean |
This switch activates consideration of premature and late engagement in the local load distribution calculation (load distribution - analytical). This results in a load-dependent increase of the contact ratio, which influences the local load distribution and all other related local values in the entire contact area.
Calculation method
The calculation is mainly based on the results of FVA research projects FVA 30 (RIKOR) and FVA 338 (DZP). For helical gears, the calculation was modified in such a way that the area of premature engagement extends only to the contact area at the start and end of the mesh.
Due to deformation of the meshing teeth under load, the distances change between the flanks of the loaded teeth facing the same direction and the not yet loaded adjacent teeth. This load-induced pitch deviation causes the next pair of not yet loaded teeth to engage earlier than with unloaded teeth [FVA project 30].
| gα | Length of path of contact |
| pet | Transverse circular pitch |
| rb1,2 | Base circle radius |
Due to the deflection of the teeth, the top edge of the driven gear comes into contact not at point A at the theoretical beginning of the engagement, but rather earlier at point 1'. Point 1' is located above the root diameter of the active flank of the driving gear and is projected for the calculation to point -1 located on the path of contact rolling line. Point -1 is before point A. In the area of premature engagement, the tip of the driven gear slips back from point 1' to the beginning of the theoretical engagement in the root diameter of the active flank of the driving gear.
The same procedure is used in the area of late engagement.
Spur gears
Here, additional lines come into contact in the area of the premature and late engagement. The stiffness of these contact lines corresponds to the stiffness of the first or last regular contact line.
Helical gears
Here, the contact in the premature and late engagement is only intermittent at the beginning and end of the mesh. The stiffness in the premature and late engagement corresponds to the first and last regular (short) line of contact in the mesh.