<< Click to Display Table of Contents >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 14: Gear-Pairs / Rack-Pinions > A: Fixed Gear Centres > Step 14.3: Compound Gear-Trains |
![]() Schematic of Compound, Three-Stage, Gear Train |
A Compound Gear Train has a minimum of: •two Gear-Pairs •more than one gear on one or more shafts In MechDesigner, it is easier to add Compound Gear-Trains than Simple Gear-Trains.
The image to the left shows a Compound Gear Train. There are three Gear-Pairs, two shafts have two gears. Therefore, it agrees the definition of the Compound Gear Train. See Also: Simple Gear-Pair, Simple Gear-Trains, Planetary Gear-Trains
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We will use the model we have done in the previous Step Add a Gear-Pair with Fixed-centers Edit the number-of-teeth as follows. Here, the number-of-teeth are: Z1=20 The Gear Ratio is Z1/Z2 = 2 Remember this basic rule:: Three Parts, three Lines, joined together with Pin-Joints. Two Lines must be in Parts that are kinematically-defined. |
Preparation for Gear-Pair 2 |
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To add a Compound Gear-Train, we use the same basic rule, again, and again. We need three Parts, each with a Line. There is a Line that is joined to a different Line, each with a Pin-Joint. Two of the Lines that are joined with a Pin-Joint are in Parts that are kinematically-defined. The third Line is in a Part that is not kinematically-defined. Gear-Pair 2: Before we start, we have a Line in a kinematically-defined Part. Line 1 / Part 1 : Line We need two more Parts and Lines. Line 2 / Part 2 : It is a new Line in the Base-Part. It will be the Line that joins the gear-centers 1.Edit the Base-Part 2.Part-Editor: Geometry toolbar > Add Line IMPORTANT rule: You must MERGE Point You can Hover + Drag to add Line 3.Part-Editor: Geometry toolbar > Merge-Points : Click Point 4.Click the graphic-area to complete the merge-points. 5.Close the Part-Editor |
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Line 3 and Part 3 : It is a new Part - it will be the Driven-Gear. 1.Mechanism-Editor: Kinematics-toolbar > Add Part: Drag to the Part 2.Mechanism-Editor : Kinematics-toolbar > Add Pin-Joint Join the start-Point of CAD-Line in Part The length the CAD-Line
We are ready to Add Gear-Pair |
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Add Gear-Pair 2 |
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Add Gear-Pair 2 1.Click Machine-elements toolbar > Add Gear-Pair 2.Click the elements, 3.Click |
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You can see the Gear-Pair 2
MechDesigner adds two new gears. This is a Compound Gear-Train. You can do the same actions to add more Gear-Pairs. |
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This image shows Compound Gear-Train with three Gear-Pairs. To make the Gears Solid 1.Use the ALT+H to move the model to the home position - this is important. 2.Click Solids Toolbar > Add Polyline 3.Click a Gear in one of the Gear-Pairs 4.Do 2 and 3 for each Gear-Pair 5.Click Solids toolbar > Add Profile 6.Click each Gear with a Polyline 7.Do 5 and 6 for each Gear 8.Shift+Click each Profile to see the Profile and Extrusion in the Selection-Window. 9.Edit each Extrusion, to offset it etc, to give a model similar to the image to the left. 10.Edit the Parts to add shafts etc. |