Planetary Gear:

An epicyclic gear train (also known as planetary gear) consists of two gears mounted in such a way that one gear's center rotates around the center of the other. A carrier links the centers of the two gears and rotates around the other, called the sun gear or sun ring, to hold one gear, called the earth gear or earth pinion. The planet and sun gears mesh so that their pitch circles roll without slip. Within, we have got a sun gear that has a fixed center point and a planet gear (or gears) that rotates around the sun gear. As they rotate within the ring gear, the planetary gears create pitch circles that can be formed into a gear train which, in turn, is hooked up to shafts of input and output. A planetary gearbox is a gearbox that is coupled with the input shaft and the output shaft. The maximum torque in the most compact form (called torque density) is transferred using a planetary gearbox.

They provide volume reductions, multiple combinations of kinematics, purely torsional reactions, and coaxial shafting. The drawbacks include high bearing loads, the constant need for lubrication, inaccessibility, and difficulty of design. In a planetary gear train, the efficiency loss is 3 percent per stage.

Angular velocity is the rate of change of an object's position angle with time.

PG-Planetary Gear

RG-Ring Gear

SG-Sun Gear

calculation:

Module(Z) = 2.5 (For all gears)

Ring Gear: Number of teeth = 46

Sun Gear: Number of teeth = 14

Formula: Z = PCD/No of teeth

PCD(RG) = 115mm

PCD(SG) = 35mm

From drawing the pcd in drawing (sketch) we can obtain the PCD(PG)=40mm

No of teeth(PG)= 2.5*40= 16

PROCEDURE FOR DOING PLANETARY GEAR MECHANISM MOTION STUDY IN SOLID WORKS

Step 1: Creating the cad model carrier.

Step 2: Create new assembly.

Step 3: Now click on design library-toolbox-ANSI metric(based on standard using)-power transmission-gears we can selecct what ever gear we can select.

Step 4: Based on before calculation by changing module, no of teeth we can import the model.

Step 5: We can make constraints make the assembly as mechanism which we needed.

CONSTRAINTS:

1. Coincide1,2,3-carrier with all the three planes only rotational motion is possible
2. Coincide4,5,6,7-carrier pin axis with gear axis
3. Coincide8,9,10,11-carrier pin face with gear face(from point 2 & 3 gear can only rotate inside the pin)
4. Coincide12,13-carrier shaft axis with the SG axis and mating it with the front axis(gear can only rotate with respect to the axis)
5. Coincide5-driving and Sketch (the path of the driving wheel pin sketched initially and then the pin axis is coincide with the one point of that sketch)

Now the assembly is ready

Step 6: click on assembly at the tools and select rotate component (In move component session). On selecting the part and rotate the motion of driven wheel can be seen so that we can make sure the constraints are given perfectly based on motion what we needed.

Step 7: Click the SOLIDWORKS add-in and enable motion study.

Step 8: Now create the new motion study and change animation to motion analysis.

Step 9: Select the motor option to give the torque to the driving wheel (we can give the rpm, time)

Step 10: Select the contact option to give the materials (we can assign material here)

Step 11: Now we can use calculate options to calculate the results.

Step 12: Now we can plot the graph using plot option. To save in excel (Right click the plot and click the save as CSV option).

Step 13: Now we can plot the graph using plot option for different cases.

Step 14: We can save the results.

Figure 1. Assembly image of Planetary Gear.

Output:

By making the gears or carrier fixed using fix option we can get the output.

Sl.No	Input	Output	Fixed	Output Figure
1	Sun Gear	Carrier	Ring Gear	2
2	Ring Gear	Carrier	Sun Gear	3
3	Sun Gear	Ring Gear	Carrier	4

Figure 2. Angular velocity plot of Planetary Gear for case 1.

Figure 3. Angular velocity plot of Planetary Gear for case 2.

Figure 4. Angular velocity plot of Planetary Gear for case 3.

Conclusion:

The output of the angular velocity can be seen in output where we can conclude that for different applications how the epicyclic gear train can be used. If we change input and output of the gear we can get different plots of output angular velocity.

Cases	Remarks
1	When time varies the angular velocity changes from 11 to 18.5 degree/sec. As time increases, we can see there is linearly increasing in angular velocity from the plot.
2	When time varies the angular velocity is 66.5 degree/sec. There is some minute deflection (up or down) in angular velocity.
3	When time varies the angular velocity is 27.7 degree/sec. There is some minute deflection (up or down) in angular velocity.

From table we can conclude that whine chnging input there is variation in angular velocity. Concerning design we should select input and output based application. The input parameters plays an major role in output such as module, no of teeth, PCD, design of carrier(some times makes some variation in results), RPM of input and material.