Planetary Gear
Aim : Motion Study of Planetary Gear.
Theory : Gears are the most important part of every machine. without gears there will be no power transmission in a machine. Well there are other sources are also for power transmission like belt drives, chains but when there is need of constant velocity ratio gears are useful there. There are many type of gear trains used for power transmission and Planetary gears are one of the epicyclic gear forms.
A Planetary gear consist of parts
1.Sun gear
2.Planet gear( can varries in numbers from 1 - 4 ).
3.Ring gear
4. Carrier shaft
There are certain specific terms which defines a gear fully
They are Module, Diameteric pitch, number of teeths etc.
Data given
Module of all the gear is 2.5
Number of teeth on ring gear is 46.
Number of teeth on sun gear is 14.
Number of Planet gear is 4.
Also rpm of input gear is 200.
Calculations
The pitch circle diameter of every gear and the number of teeth can be calculated by the relation
`m = d/t`
here m is module
d is pitch circle diameter
t is number of teeth
1. Sun gear
m = 2.5 , t = 14
`d = m*t`
`d=2.5*14`
`d = 35`
2. Ring gear
m = 2.5 , t = 46
`d = m*t`
`d = 2.5*46`
`d = 115`
3. we know
`t_s+2t_p=t_r`
from this we get number of teeth on planet gear to be 16.
now `d= m*t`
`d = 2.5*16`
d = 40
How to make assmebly of planetary gear
Step 1. First of all start solidworks and choose new file and select assembly.
Step 2. Go to toolbox and select built in gears from there and modify them according to the data given.
Step 3. Make all gears like this(can also take help of the videos provided in the course).
Step 4. Now select a plane to sktech and draw the sketch as shown below.
Step 5. Exit the sketch.
Step 6. Now provide the mate to make the assembly fixed(as show in the video in course).
Motion Study of Planetary Gear
step 7. Click on SolidWorks addin and enable the SolidWorks Motion Study.
We are going to 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 |
input rpm = 200
Plots And Results
case 1
Input = Sun gear
Output = Carrier
Fixed part = Ring gear
Rpm = 200
No. of frames = 25 (default)
Here in this plot it can be seen that when a 200 rpm speed is given to the input part (sun gear ) the output speed that we get on carrier is somewhere around 265deg/sec.
case 2
Input = Ring gear
Output = Carrier
Fixed part = Sun gear
Rpm = 200
No. of frames = 25 (default)
Here in this plot it can be seen that when the input of 200 rpm is given to the input part( ring gear ) the output speed that we get on the carrier is somewhere around 900deg/sec.
case 3
Input = Sun gear
Output = Ring gear
Fixed part = Carrier
Rpm = 200
No. of frames = 25 (default)
Here in this plot it can be seen that when the input of 200 rpm is given to the sun gear the output speed that we get on the ring gear is arpund 381deg/sec.
Conclusions
After doing the Motion study of all the given conditions it can be concluded that the planetary gear assembly can generate different output speed for the same input speed just by changing the input part and the output part .
Drive link
https://drive.google.com/drive/folders/19PErHTyT6XSyda3kqdc_gpM3N8mt9uDT?usp=sharing