Creating a Planetary Gear System in SolidWorks: A Comprehensive Guide

Welcome back to the Multibody Dynamics using SolidWorks blog series! In this part of blog series, we will guide you through the process of creating a planetary gear system. Planetary gears, also known as epicyclic gear trains, are commonly used in automatic transmissions and other mechanical systems. This blog outlines the step-by-step method for setting up, assembling, and simulating this system using SolidWorks. 

Step 1: Starting the Assembly and Importing Components 

First, open SolidWorks and create a new assembly by navigating to File > New > Assembly. In this case, we are not going to create new parts manually; instead, we will import them from the Design Library. Start by importing a ring gear from the Toolbox. Make sure the correct standards are selected—choose the ANSI Inch specification. 

Click on Power Transmission, then navigate to Gears. For the ring gear, select Internal Spur Gear and drag it into your assembly. Now, define some parameters: 

• Diameter Pitch: 1 
• Number of Teeth: 32 
• Pressure Angle: 20° 
• Face Width: 2 inches 
• Outside Diameter: 38 inches 

Once these values are set, click OK to add the ring gear to the assembly. 

Step 2: Importing the Sun and Planetary Gears 

Next, import the Sun Gear. Navigate back to Power Transmission > Gears, and this time select Spur Gear. After dragging it into the assembly, define the following parameters for the Sun Gear: 

• Number of Teeth: 12 
• Pressure Angle: 20° 
• Face Width: 2 inches 
• Nominal Shaft Diameter: 8 inches 

Repeat this process for the planetary gears, but with different specifications. Import the gears and set the following: 

• Number of Teeth: 10 
• Pressure Angle: 20° 
• Face Width: 2 inches 
• Nominal Shaft Diameter: 5 inches 

If you enter incorrect values at any stage, you can easily edit the properties by right-clicking on the gear and selecting Edit Toolbox Properties. 

Step 3: Positioning the Gears Using Sketches 

To align the gears properly, create sketches that represent the pitch circles of the gears. Select the Right Plane in the assembly and create a sketch using the Circle Tool. 

For each gear, input the corresponding pitch circle diameter: 

• Ring Gear: 32 inches 
• Sun Gear: 12 inches 
• Planetary Gear: 10 inches 

Ensure that the pitch circles are tangent to each other. To achieve this, apply tangent constraints between the center circle and the planetary circle. You may also need to constrain the center of the planetary gear and the Sun Gear to make them horizontal. Exit the sketch when you have completed these constraints. 

Step 4: Assembly and Mates 

Now that the gears are sketched and their pitch circles defined, we can proceed to the assembly. Start by ensuring that the ring gear is not fixed. If it is, right-click on the gear and select Float. Align the ring gear and Sun Gear by using concentric mates with the sketch you created. 

Do the same for the planetary gear, making sure you apply concentric mates for accurate alignment. Once the gears are positioned in the correct plane, constrain them to the Right Plane by selecting the top faces of the gears and applying coincident mates. 

Step 5: Setting Gear Mates for Motion 

To simulate motion, we need to create gear mates that establish relationships between the gears. Navigate to Assembly > Mate > Mechanical Mates and select Gear Mate. For the first mate, select the Sun Gear and the planetary gear, specifying the number of teeth for both (Sun: 12, Planetary: 10). 

Repeat the process for the planetary gear and the ring gear, entering the number of teeth (Planetary: 10, Ring: 32). These mates ensure that the gears will rotate together, transferring motion between them as intended. 

Step 6: Running the Motion Study 

With the assembly complete, we can now set up the motion simulation. Go to Motion Study at the bottom of the screen, and select Motion Analysis. If this option isn’t available, ensure that SolidWorks Motion is enabled under SolidWorks Add-ins. 

The next step is to add a motor to drive the Sun Gear. Click on Motor, select the Sun Gear axis, and set a rotation speed of 10 RPM. After that, we need to set contact pairs to simulate the interaction between the gears. Select the contact faces of the gears and assign Steel as the material. 

Finally, click Calculate to run the simulation. If everything has been set up correctly, the Sun Gear will drive the planetary gear, which in turn will rotate the ring gear. 

Conclusion 

Congratulations! You’ve successfully modeled and simulated a planetary gear system in SolidWorks. The gear mates and contact settings ensure that the motion is accurately transferred between the gears, providing a realistic simulation of how the system operates in real life. This tutorial is a part of our Multibody Dynamics Course at Skill-Lync where we dive deeper into the SolidWorks simulation process and its applications in mechanical engineering projects. 

In our next post, we’ll explore advanced motion studies and how to analyze gear stress and efficiency under different loads. Stay tuned! 

This blog is part of our ongoing series on Multibody Dynamics. 

If you missed the previous posts, check them out here.   

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