Planetary Gear
Aim :
To design a planetary gear assembly using the following inputs
- Ring Gear
- Module = 2.5 (You must use the metric system in design modeler)
- Number of teeth = 46
- Sun Gear
- Number of teeth = 14
- Input Speed of the Gear = 200 rpm.
- Number of planet gears = 4
The dimensions of the carrier depend on the shaft diameter of the planet gear.
And run a simulation on the following cases,
| Sl.No | Input | Output | Fixed |
| 1 | Sun Gear | Carrier | Ring Gear |
| 2 | Ring Gear | Carrier | Sun Gear |
| 3 | Sun Gear | Ring Gear | Carrier |
Theory :
A Planetary gear assembly, also called an epicyclic gear assembly, is type of gear assembly where at least one gear revolves around another gear while being held stationary. A planetary gear assembly consists of one sun gear (at the centre), one ring gear (outermost gear) and at least one planet gear (meshed between sun and planetary gear). Both sun and planet gear are gears with external teeth while the ring gear has internal teeth.
The above challenge deals with an assembly having one sun gear, one planetary gear and 4 planet gears which are mounted on a carrier.
A planetary gear assembly is mainly used in Torque Converter Automatic Tranmissions and lathes, amongst many other important applications.
Calculation :
Module = Pitch Circle Diameter/No of teeth
Module for all gears = 2.5
Number of teeth on Planet Gear = (No of teeth on Ring gear - No of teeth on sun gear)/2
Number of teeth on Planet Gear = (46 - 14)/2 = 16
PCD of Ring gear = 2.5*46 = 115mm
PCD of Sun Gear = 2.5*14 = 35m
PCD of Planet Gear = 2.5*16 = 40mm
Modelling and Assembly :
Final Assembly
Ring Gear
Carrier
Planet Gear
Sun Gear
Plots :
Angular Velocity of Carrier with Ring gear fixed
Angular velocity of carrier with Sun Gear fixed
Angular velocity of Ring gear with Carrier fixed
Conclusions :
Since the input speed is a constant value of 200rpm in all cases, the output angular velocities are also constant.
Speed of Carrier when Ring gear is fixed and sun gear is given input of 200 RPM = 286 degree/sec = 48 RPM
Speed of Carrier with Sun gear fixed and Ring gear is given an input of 200 RPM = 931 degree/sec = 155 RPM
Speed of Ring gear with Carrier fixed and Sun gear is given an input of 200 RPM = 378 degree/sec = 63 RPM
All the above simulations were carried out at 25 FPS which is the reason for the small irregularities in the output.