Add a Gear-Pair with an Orbiting center

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Navigation:  Getting Started Tutorials - MechDesigner > Tutorial 14: Gear-Pairs > Fixed Gear and Orbiting Gear Arrangements > Option 2: Orbiting Gear Centres >

Add a Gear-Pair with an Orbiting center

Option 2: Orbiting center Gear-Pairs

Arrangement 1: Orbit a gear around the outside of a gear

Arrangement 2: Orbit gear around the inside of a gear.

Preparation for Option 2

Elements to select to add an Epicyclic Gear

STEP 1: Edit a kinematically-defined PartRed-14-3

STEP 2: Add a LineRed-14-1b

STEP 3: Close the Part-Editor

STEP 4: Add two Parts Red-14-3Red-14-2

STEP 5: Join PartRed-14-3 to LineRed-14-1b with a Pin-JointRed-14-5

STEP 6: Join the PartRed-14-2 to the other end of PartRed-14-3 with a Pin-JointRed-14-6

In this configuration, you MUST use the Points that are at the end of the CAD-Lines in the Parts.

STEP 7: Add a Motion-Dimension FB between the LineRed-14-1b and the CAD-LineRed-14-3

Note: The CAD-LineRed-14-3 along the center of a Part has a dimension.

Use Add Gear-Pair


Click Machine-elements toolbar > Add Gear-Pair


Add Gear-Pair opens in the Command-Manager.

Select these four elements. Refer to the images above to identify the Elements.

1.The Green Line on Gear Part 1 Red-14-1b

2.The Blue Line' on Gear Part 2 Red-14-2

3.The Green Line between the Gear centers Red-14-3

4.The Dimension of the Cad-Line that joins the Gear centers Red-14-7

In the Command-Manager we use the terms:

Green Line is usually the CAD-Line in a kinematically-defined Part.

Blue Line is usually the CAD-Line in Free Part

Video - Add Orbiting Gear-Pair


Tutorial 14:

Add Gear-Pair - Orbiting


Edit Number-of-Teeth, Module and Mesh


Default Gear-Pair: Orbiting Gear rotates around the outside of a Sun Gear

In the default, the two Gears have:

an external tooth form.

the same number-of-teeth

module that will minimize a change of length to the Line-of-centers.

The module and the number-of-teeth on each Gear give the length of the Line-of-centersRed-14-3.


Edit the Number-of-Teeth and Module

Gear 1 = 60 Red-14-1b

Gear 2 = 20 Red-14-2

Module = 2

Gear Diameter = Module * number-of-teeth

Length of Line-of-centers = Module * ((Number-of-Teeth Gear 1 + Number-of-Teeth Gear 2) / 2).

= 2 * ((60 + 20)/2) = 80mm


Make the Orbiting Gear rotate around the inside of a Ring Gear

When the Gears have a different number-of-teeth, it is possible to make one of the gears internal.

Gear 2 moves inside Gear 1.

Length of the Line-of-centers is now:

= 2 * ((60 - 20)/2) = 40mm