Getting Started Tutorials - MechDesigner > Tutorial 14: Gear-Pairs / Rack-Pinions > A: Fixed Gear Centers

Add a Simple Gear-Pair with Fixed centers

Simple Gear-Pair - Prepare

GST-14.A-01

STEP 1: Add a Line to a Part that is kinematically-defined

1.Edit a kinematically-defined Part (usually the Base-Part) with the Part-Editor.

2.Geometry toolbar > Add Line | Drag to add the Line

3.Geometry toolbar > Add Dimension | Add the dimension to the Line.

The length of the Line is not important.

4.Constraint toolbar> Add constraints as required.

5.Close the Part-Editor

GST-14A-101

STEP 2: Add a rotating-Part that is kinematically-defined

1.Kinematic-elements toolbar > Add Part | Drag to add a Part

2.Kinematic-elements toolbar > Add Pin-Joint

Click the start-Point of the CAD-Line in Part

Click the start-Point of Line

3.Kinematic FB toolbar > Add Motion-Dimension FB

Click the: Pin-Joint

Click Line

Click CAD-Line in Part

Part must be a kinematically-defined. It is not important how it becomes kinematically defined.

GST-14A-102

STEP 3: Add a rotating-Part that is free

1.Kinematic-elements toolbar > Add Part | Drag to add a Part

2.Kinematic-elements toolbar > Add Pin-Joint

Click the start-Point of CAD-Line in Part

Click the end-Point of Line in the Base-Part.

Add Gear-Pair

GST-14.A-03

STEP 1: Start the Add Gear-Pair command

1.Expand the Machine-elements toolbar

2.Click Add Gear-Pair

The Command-Manager has four selection-boxes.

STEP 2: Select the four elements

See images above for element numbers

1.Green Line on Gear 1: Line in Part

2.Green Line on Gear 1: Line in Part

3.Green Line Joining Gears: Line that joins Gear centers:

Line will be the Line-of-Centers.

4.Center Distance Dimension: Distance Dimension: Length Dimension of Line

STEP 3: Complete the command

1.Click to complete the command

The default Gear-Pair has an External Mesh, and the gears have equal number-of-teeth.

GST-14.A-04

The default Gear-Pair parameters

•External tooth form (also called External Mesh)

•Number-of-Teeth - Teeth on Driving Gear = Teeth on Driven Gear

•Module is almost random!

The Length-dimension of Line is now driven by the Number of Teeth and Module parameters. You cannot edit its dimension in the Part-Editor.

Video - Add Gear-Pair

Basic Parameters: Number-of-Teeth, Module and Mesh

Open the Gear-Pair dialog to edit the Gear-Pair parameters. E.g: double-click a gear, or see How to open a dialog.

GST-14.A-05

Mesh: External

Gear Pair dialog > Define tab > Gear Mesh & Number-of-Teeth > Mesh : External

•Number of Teeth, z1 (Driving-Gear) : 60

•Number of Teeth, z2 (Driven Gear) : 20

Gear Pair dialog > Parameters tab > Gear Tooth Parameters: >

•Module, m : 2

Length of Line (External Mesh)= 2(module) × (60(# Teeth ) + 20(# Teeth)) / 2) = 80mm

GST-14.A-06

Mesh: Internal.

Gear Pair dialog > Define tab > Gear Mesh & Number-of-Teeth > Mesh : Internal

The Gear with fewer teeth moves inside the other Gear. An internal mesh is not possible when the Gears have equal number-of-teeth.

When the Gears have an internal mesh, we subtract the number of teeth to find the length of the Line of centers.