How to add a Simple Gear-Pair with Fixed Centres

Basic Preparation

GP-FC-001

STEP 1: Add a Line to a Part (Part 1) that is kinematically-defined
1.Edit a kinematically-defined Part with the Part-Editor
2.Part-Editor : Geometry toolbar > Add Line | Drag to add the LineRed-14-1b
3.Part-Editor: Geometry toolbar > Add Dimension | Add the dimension to the LineRed-14-2.

The exact length of the Line is not important.

4.Part-Editor: Constraint toolbar> Add constraints as required.
5.Close the Part-Editor

STEP 2: Add a Part (Part 2), and join it with a Pin-Joint between its CAD-Line and one end of the Line.
1.Mechanism-Editor: Kinematic-elements toolbar > Add Part | Drag to add a PartRed-14-3
2.Mechanism-Editor: Kinematic-elements toolbar > Add Pin-Joint | Join the CAD-LineRed-14-5 of PartRed-14-3 with Pin-JointRed-14-4 to the end of LineRed-14-1b

PartRed-14-3 must be a kinematically-defined. It is not important how it becomes kinematically defined. To add a Motion-Dimension FB is one example.

STEP 3: Add a Motion-Dimension FB to kinematically-define the Part
1.Mechanism-Editor: Kinematic-elements toolbar > Add Motion-Dimension FB | Click the:
a.Pin-JointRed-14-4
b.LineRed-14-1b (STEP 1)
c.CAD-LineRed-14-5 in PartRed-14-3 (STEP2)

STEP 4: Add a Part, (Part 3) and join it with a Pin-Joint to the other end of the Line. This Part is a free Part.
1.Mechanism-Editor: Kinematic-elements toolbar > Add Part | Drag to add a PartRed-14-6
2.Mechanism-Editor: Kinematic-elements toolbar > Add Pin-Joint | Join the CAD-LineRed-14-8 in PartRed-14-6 with Pin-JointRed-14-7 to the other end of LineRed-14-1b

GP-FC-002

Add Gear-Pair

Icon-AddGearPair

Click Machine-elements toolbar > Add Gear-Pair

GP-FC-003

The Command-Manager has four selection-boxes.

Select the elements in the graphic-area (see images above to identify the four elements) :

1.Green LineRed-14-5 (in PartRed-14-3 )
2.Blue LineRed-14-8 (in PartRed-14-6 )
3.Green LineRed-14-1b that joins Gear Centres: LineRed-14-1b will be the 'Line-of-centres'.
4.Centre Distance DimensionRed-14-2: Length Dimension of LineRed-14-1b

Click OK-tiny-11-15 to complete the command

MechDesigner adds the Gear-Pair.

In the default case: it has an External Mesh, and the two gears have the same number-of-teeth.


In the Command-Manager we use the terms:

Green Line. This relates to a Line in a kinematically-defined Part
Blue Line. This relates to a Line in the Free Part ; or a Part that is not kinematically-defined, It becomes kinematically-defined after we add the Gear-Pair.

Video - Add Standard Gear-Pair

 

Tutorial 14:

Add Gear-Pair

 

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

GP-FC-004

The default Gear-Pair parameters

External tooth form (also called External Mesh)
Number-of-Teeth - Teeth on Driving Gear Red-14-2= Teeth on Driven GearRed-14-3
Module is almost random!

The Length-dimension of LineRed-14-1b is now driven by the Number of Teeth and Module parameters. You cannot edit its dimension in the Part-Editor.


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

GP-FC-005

Mesh: External

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

Number of Teeth, z1 (Driving-Gear) : 60Red-14-2
Number of Teeth, z2 (Driven Gear) : 20Red-14-3

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

Module, m : 2

Length of LineRed-14-1b (External Mesh)= 2(module) × (60(# TeethRed-14-2 ) + 20(# TeethRed-14-3)) / 2) = 80mm

GP-FC-006

Mesh: Internal.

Gear Pair dialog-box > 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 Centres.

Length of LineRed-14-1b (Internal Mesh)= 2(module) × (60(# TeethRed-14-2 ) - 20(# TeethRed-14-3)) / 2) = 40mm

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd