﻿ Step 6D2.1: Prep 2A: Add a Gear Pair & Trace Point

Step 6D2.1: Prep 2A: Add a Gear-Pair & Trace-Point

We will add a Gear-Pair with an orbiting gear.

 Preparation 2A: Add an Eccentric Gear-Pair

The Internal Gear will be fixed to the Base-Part. The External Gear will orbit the inside of it. The External Gear, that is inside the Internal Gear, has 1/3 the number-of-teeth.

 STEP 1: Add a Rotating Part - see Tutorial 1 for a complete list of instruction. This is a Summary:
 1 Add a Line to the Base-Part.
 2 Add a Part to the Mechanism-Editor
 3 Add a Pin-Joint between the Part and the Point at the left of the Line added to the Base-Part
 4 Add a Motion-Dimension FB to identify the Part as a Rocker
 6 Connect the Linear-Motion FB to the Motion-Dimension FB

 STEP 2: Add a Epicyclic Gear-Pair
 2 Add Pin-Joint between the end-Point of the Rocker and the start-Point of the new Part

 1 Click Machine element toolbar > Add Gear-Pair

The four elements to add this Gear-Pair are:

The Horizontal Line in the Green Base-Part

The CAD-Line in a Green Part that connects the Base-Part to the Added-Part

The length dimension of the CAD-Line

Note: The Part-Editor will open automatically for you to select the length dimension of the Line.

To close the Command-Manager you can:

 1 Right-click in the graphic-area (a shortcut)

- or -

 2 Click  in the Command-Manager

MechDesigner draws the Gear-Pair with an

 • External mesh
 • Equal Number of Teeth (z1 & z2)
 • A typical module (m)

Note: for information only. Pitch Diameter (D)  = m.z1  and m.z2 (5.20=100mm) | Circular Pitch (Pc) = m. π = D.π  ∕  N

Use Edit menu> Application-Settings > Graphic tab > Display Colours  > Gear-Pair and change the colour to give a good contrast with Background colour.

 STEP 4: Edit the Gear-Pair
 1 Double-Click the Gear-Pair in the graphic-area (or see How to open a dialog-box)

The Gear-Pair dialog-box opens. Edit the Gear-Pair as follows:

 • Define tab : Gear Mesh and Teeth > Gear 1: 60 Teeth | Gear 2: 20 Teeth | Internal Mesh (radio-button)
 • Parameters tab > Gear Tooth Parameters > Module = 5
 2 Click  to close the Gear-Pair dialog-box.
 3 Cycle the model (ALT+C) to see that the Large Gear is stationary, and the Small Gear rolls around the inside of the Large Gear.

 STEP 5: Edit the Part with the small gear with 20 teeth to add a new Line

We want the length of the new Line to equal the radius of the small Gear. The Pitch Diameter (D) = m × z1  and 5 × 20 =100mm

 2 Part-Editor: Geometric Constraint > Coincident Constraint | Click the start-Point of the Line and the start-Point of the CAD-Line
 3 Part-Editor: Geometric Constraint> Add Equal | Click the new Line and the original CAD-Line
 4 Part-Editor: Add Horizontal : click the new Line
 5 Exit the Part-Editor

 STEP 6: Add a Trace-Point to the end-Point of the new Line.
 1 Click Kinematic-elements toolbar : Add Trace-Point
 2 Click the end-Point of the new Line
 3 Click in the Command-Manager - or - Right-click.

MechDesigner shows the Trace-Point.

If you cycle the machine (ALT+C as the Shortcut) you will see the Point at the end of the Line move along the Trace-Point.

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