MechDesigner Reference & User Interface > 2.2 Mechanism-Editor: > Machine elements > Mechanism

Add Gear-Pair

Terminology and definitions:

Gear-Pair :	Two gear wheels with gear-teeth that are in mesh. When one gear rotates the other gear must also rotate. The angular velocity of each gear is related to the number-of-teeth on each gear-wheel.
External Mesh :	The gears have teeth that diverge out from their centers-of-rotation.
Internal Mesh :	One of the gears has teeth that converge to its center-of-rotation.
Simple Gear-Pair :	Two gears that rotate about fixed centers.
Epicyclic Gear-Pair :	One gear orbits around the center of the other gear.

Kinematic state before you do Add Gear-Pair

There are two Parts (rotating-Parts) that are joined with Pin-Joints to the start-Point and end-Point of a Line in a third Part.

One of the rotating-Parts is kinematically-defined.

The other rotating-Part is not kinematically-defined. It has one degree-of-freedom.

Kinematic state after you do Add Gear-Pair

Add Gear-Pair removes one degree-of-freedom.

The motion of each Part is now found from the number-of-teeth on each gear-wheel in the Gear-Pair.

Kinematics-Tree of Gear-Pair

Add Gear-Pair removes one degrees-of-freedom.

MD-ADD-GEARPAIR-KINEMATICS-TREE

Gear-Pair

Before you do Add Gear-Pair, a rotating-Part that is kinematically-defined, and a rotating-Part that has one degree-of-freedom.

After you do Add Gear-Pair, the rotating-Part that had one degree-of-freedom now becomes a Geared Rocker and it is kinematically-defined.

Preparation

A Simple Gear-Pair and of an Epicyclic Gear-Pair have different motions. However, the elements-types you prepare and select to do Add Gear-Pair are the same.

Simple Gear-Pair

MD-ADD-GEARPAIR-0

Three(3) Parts, three(3) Lines, two(2) Pin-Joints ...

Line & Line are in Green Parts that are kinematically-defined

Line is in a Part that is not kinematically-defined

Lines are joined with Pin-Joints to each end of Line

Line has a dimension (in the Part-Editor)

Line is kinematically-defined after you do Add Gear-Pair.

Epicyclic Gear-Pairs

MD-ADD-GEARPAIR--EPI-0

Three(3) Parts, three(3) Lines, two(2) Pin-Joints ...

Line & Line are in Parts that are kinematically-defined

Line is in a Part that is not kinematically-defined.

Lines are joined with Pin-Joints to each end of Line

Line has a dimension (in the Part-Editor)

Line (and the Part) is kinematically-defined after you do Add Gear-Pair.

Add Simple Gear-Pair

MD-CM-AddGearPair-0

STEP 1: Click Add Gear-Pair

1.Mechanism-Editor: Add menu > Mechanism menu > Add Gear-Pair

- or -

1.Mechanism-Editor: Machine-elements toolbar > Add Gear-Pair

There are four elements to select in the Command-Manager

MD-ADD-GEARPAIR-1

STEP 2: Select the four elements

1.Mechanism-Editor > Click Line

2.Mechanism-Editor > Click Line

3.Mechanism-Editors : Click Line

MD-ADD-GEARPAIR-2

STEP 2: continued...

The Part-Editor opens automatically.

4.Part-Editor: Click the Dimension

The Part-Editor closes automatically.

MD-CM-AddGearPair-full

STEP 3: Complete the Command

5.Command-Manager: Click in the Command-Manager.

Result:

The Gear-Pair is in the graphic-area.

The default Gear-Pair has an External Mesh and they have same number-of-teeth.

The length of the Line between the Gear centers - called the Line-of-centers - becomes a Driven-Dimension. (The Length Dimension = (# Gear-Teeth 1 + # Gear-Teeth 2) * Module)

The output Part is a Geared-Rocker in the Kinematics-Tree.

To edit the Gear-Pair parameters: see Gear-Pair dialog-box

MD-ADD-GEARPAIR-3

Add Epicyclic Gear-Pair