﻿ MechDesigner Reference & User Interface > 2.2 Mechanism-Editor: > Machine elements > 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. Driving Part : The rotating-Part that is kinematically-defined, and whose motion is defined (even if it is stationary) before you do Add Gear-Pair Driven Part : The rotating-Part whose motion is defined after you do Add Gear-Pair by the Driven-Part, the Number-of-Teeth on each Gear in the Gear-Pair, and the Mesh. 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 three Parts. There is a Line in a Part that is kinematically-defined. The Line must have a dimension to define its length. A Part is joined with a Pin-Joint to each end of the Line - two rotating-Parts. One rotating-Part is kinematically-defined. The other rotating-Part is not kinematically-defined before you do Add Gear-Pair. The three Parts have one degree-of-freedom.

#### Kinematic state after you do Add Gear-Pair

 Add Gear-Pair removes the one degree-of-freedom from the three Parts. The motion of Driven Part is found from the number-of-teeth , and mesh on each gear-wheel in the Gear-Pair.

### Kinematics-Tree of Gear-Pair

Gear-Pair

 Before you do Add Gear-Pair, there is 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 becomes a Geared Rocker and it is also kinematically-defined.

### Preparation

#### Simple Gear-Pair

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

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.

STEP 1: Click Add Gear-Pair (Simple)

There are four elements to select in the Command-Manager

STEP 2: Select the four elements

 1.Mechanism-Editor > Click Line 2.Mechanism-Editor > Click Line 3.Mechanism-Editors : Click Line

STEP 2: continued...

The Part-Editor opens automatically.

 4.Part-Editor:  Click the Dimension

The Part-Editor closes automatically.

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

To edit the Gear-Pair parameters:

STEP 1: Click Add Gear-Pair (Epicyclic)

There are four elements to select in the Command-Manager

STEP 2: Select the four elements

 2.Mechanism-Editor > Click Line 3.Mechanism-Editor > Click Line 4.Mechanism-Editor > Click Line

STEP 2: continued...

The Part-Editor opens automatically.

 4.Part-Editor:  Click the Dimension

The Part-Editor closes automatically.

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 the gears have same number-of-teeth. The length of the Line between the Gear centers - called the Line-of-centers - becomes a Driven-Dimension. (Length = (# Gear-Teeth 1 + # Gear-Teeth 2) * Module) The output Part is a Geared-Rocker in the

To edit the Gear-Pair parameters,