Profile Shifted External Helical Gear - Normal
Profile Shifted Helical gears feature profile adjustment to allow for variations in design such as a non-standard centre distance. The table below provides an example of a helical gear pair and the calculations used to derive the design values.
The following parameters are required as inputs:
Module
Pressure Angle. Usually one of 14.5°, 20° or 25°.
Helix Angle
Number of Teeth, Pinion and Gear
Working Centre Distance.
Coefficient of Profile Shift, Pinion and Gear. Note that the Sum Coefficient of Profile Shift is a calculated value; it is the distribution of this value between Pinion and Gear that is required as a user input.
Height. This is the height or width of the gear. It is only relevant to calculation of the Axial Contact Ratio.
No. | Item | Symbol | Formula | Pinion | Gear |
|---|---|---|---|---|---|
1 | Normal Module | Design Parameter | 3 | ||
2 | Normal Pressure Angle | Design Parameter | 20° | ||
3 | Helix Angle | Design Parameter | 30° | ||
4 | Number of Teeth | Design Parameter | 12(L) | 60(R) | |
5 | Working Centre Distance | Design Parameter | 125 | ||
6 | Normal Coefficient of Profile Shift | Design Parameter Note #1 | 0.09809 | 0.0000 | |
7 | Sum Coefficient of Profile Shift | 0.09809 | |||
8 | Radial Module | 22.79588° | |||
9 | Standard Centre Distance | 124.7077 | |||
10 | Radial Pressure Angle | 22.79588° | |||
11 | Radial Involute Function | 0.022414 | |||
12 | Radial Working Pressure Angle | 23.1126 | |||
13 | Radial Working Involute Function | 0.23405 | |||
14 | Centre Distance Increment Factor | 0.09744 | |||
15 | Pitch Diameter | 41.569 | 207.846 | ||
16 | Base Diameter | 38.322 | 191.611 | ||
17 | Working Pitch Diameter | 41.667 | 208.333 | ||
18 | Addendum | 3.292 | - | ||
- | 2.998 | ||||
19 | Deddendum | 3.456 | - | ||
- | 3.750 | ||||
20 | Whole Depth | 6.748 | |||
21 | Outside Diameter | 48.154 | 213.842 | ||
22 | Root Diameter | 34.658 | 200.346 | ||
23 | Radial Contact Ratio | Note #2 | 1.294 | ||
24 | Height of Gear | Design parameter | 20 | ||
25 | Axial Contact Ratio | 1.061 | |||
25 | Total Contact Ratio | 2.355 | |||
- #1
The values for are manually assigned and normally sum to equal the Sum Coefficient of Profile Shift (Item 7).
- #2