How to add a Fixed Gear-Pair

STEP 1:

Use the Part-Editor to edit a kinematically-defined Part - for example the Base-Part

STEP 2:

Add a Line

STEP 3:

Add a dimension to the Line. The exact length of the Line is not important.

See image below.

STEP 5:

Add two Parts

STEP 6:

Join the Parts with Pin-Joints to the Line

Use the Points that are at the end of Line and the Points that are at the end of the CAD-Lines in Parts.

STEP 7:

Add a Motion-Dimension FB between Line and the CAD-Line in Part

The Part may also be a child to a Dyad, or be Geared Rocker.

Connect wires from other FBs to the Motion-Dimension FB to move Part.

When you do Machine Elements toolbar > Add Gear-Pair, the Command-Manager shows four selection-boxes.

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

1.	'Green Line' on Gear Part : Part 1 for Gear 1

2.	'Blue Line' on Gear Part 2: Part for Gear 2

3.	'Green Line' that joins Gear Centres: Line will be the 'Line-of-centres'.

4.	Centre Distance Dimension: Length Dimension

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

When MechDesigner adds the Gear-Pair, the default Gears have an:

•	Module that does not change the length you give to the Line-of-centres - much

The Module and the Number-of-Teeth on each Gear give the length of the Line-of-Centres.

Double-click the Gear-Pair to open the Gear-Pair dialog-box.

Edit the Number-of-Teeth and Module

In the Gear-Pair dialog-box, edit the Number-of-Teeth and Module:

•	Gear 1 = 60 ; Gear 2 = 20 ; Module = 2

Gear Diameter = Module * Number-of-Teeth

Length of Line-of-centres = Module * (number-of-teeth Gear 1 + Number-of-Teeth Gear 2) / 2

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

Make Gear 1 'Internal'.

When the Gears have a different number-of-teeth, you can select the 'Internal' Radio button.

The Gear with less teeth moves inside the other Gear.

The Gear with more teeth has the Internal teeth form.

In this example:

Length of the Line-of-centres is:

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