Getting Started Tutorials - MechDesigner > Tutorial 17: Belts and Pulleys > Step 17.2: Option 1 - Fixed Pulley Centers > 1 Driving-Pulley, 3 Driven-Pulleys, 2 Belts

Fixed Pulley centers : Two or more Pulley Sets

Use Two Belts to:

•Give a larger speed reduction

•More flexible ratios.

The image to the left is a schematic with:

•Three shafts

•Two belts

Step 1: First Belt

Add Motion-Path of Belt 1 and two Rockers

STEP 1: Add a closed sketch-path to represent the path of the belt.

1.Edit the Base-Part :

Add a sketch-path to represent the path of a Belt. In this example, the sketch-path has two Arcs and two Lines.

Click Add Dimension : Click each Arc . The radius of each Arc is not important.

Click Add Dimension Click the center-Points of the Arcs. The distance between the Arcs is not important

2.Exit the Part-Editor

STEP 2: Add a Line to the sketch

1.Edit the Base-Part

Click Add Line - drag in the graphics-area to add the Line.

Click Add Coincident Constraint : Click the start-Point of the Line and the center-point of an Arc.

Click Add Horizontal Constraint : Click the Line

Click Add Dimension : Click the Line

2.Exit the Part-Editor

STEP 3: Add a Motion-Path FB

1.Kinematic FB toolbar > Add Motion-Path FB

Click one of the sketch-elements in the sketch-path that represents the belt.

Click in the Command-Manager

A Motion-Point is at the start-Point of the sketch-element that you select.

STEP 4: Add the Parts for the Pulley's

1.Add Part × 2: × Drag to add the two Parts. The length of each Part is not important.

2.Add Pin-Joint: Click the start-Point of a Part and the start-Point of the Line .

3.Add Pin-Joint: Click the start-Point of the other Part and the center-Point of the other Arc.

4.Add Motion-Dimension FB : Click the Pin-Joint ; Click the Line ; Click the CAD-Line along the Part , Click in the Command-Manager.

One rotating-Part is kinematically-defined (it is a Rocker), the other rotating-Part is not kinematically-defined.

Use Add Pulley

STEP 1: Start the Add Pulley command

1.Machine elements toolbar > Add Pulley

Add Pulley opens in the Command-Manager.

STEP 2: Select the elements

Do Add Pulley to the rotating-Part that is kinematically-defined (the Rocker)

1.Click the Pin-Joint

2.Click the Motion-Path FB

The Part-Editor opens with sketch-path to which you add the Motion-Path FB

3.Click the radius Dimension of the Arc

The Part-Editor closes

4.Click the Part joined with a Pin-Joint at the center of the Arc.

Click in the Command-Manager.

We add for you a Pulley.

Do Add Pulley again, to add a Pulley to the right-hand Arc and Part. This a Driven-Pulley.

Notes:

•The Driving-Pulley is the Rocker.

•Linear-Speed of Belt = Radius of Driving-Pulley × Angular-Velocity of Driving-Pulley(Rocker)

•Angular-Velocity of the Driven-Pulley = Linear-Speed of Belt ÷ Radius of Driven-Pulley

STEP 3: Edit the Pulleys

Double-click each Pulley to open the Pulley dialog

Enter:

Driving-Pulley : Number-of-Teeth = 50

Driven-Pulley : Number-of-Teeth = 72

Step 2: Add Second Belt

Add Motion-Path of Belt 2, and two Pulleys

STEP 1: Add a closed sketch-path to represent the path of the Belt #2

1.Edit the Base-Part :

2.Add a sketch-path to represent the path of a Belt.

3.Click Geometry toolbar: Merge-Points: Merge the center-Point of Arc #1 on Belt #2, with the center-Point of the Arc #2 on Belt #1

4.Click Add Dimension : Click each Arc . The radius of each Arc is not important.

5.Close the Part-Editor

STEP 2: Add a Motion-Path FB

1.Kinematic FB toolbar > Add Motion-Path FB

Click one of the sketch-elements in the sketch-path that represents the Belt #1.

Click in the Command-Manager

A Motion-Path FB is in the graphics-area.

A Motion-Point is at the start-Point of the sketch-element that you select.

STEP 3: Add the Part for the Driven-Pulley of Belt #2

We need one more Part for the Driven-Pulley of Belt #2 . It is a Part that is free before we do Add-Pulley.

1.Add Part: Drag to add the Part. The length of the Part is not important.

2.Add Pin-Joint: Click the start-Point of the Part and the center-Point of the other Arc.

Use Add Pulley

STEP 1: Add the Driving-Pulley for Belt#2

1.Machine elements toolbar > Add Pulley

Add Pulley opens in the Command-Manager.

You must select four elements - see images above and left

1.Click Pin-Joint

2.Click Motion-Path FB

The Part-Editor opens to show the sketch-path of the Belt in the Base-Part

3.Click the radius Dimension of the Arc sketch-element, at the Pin-Joint

The Part-Editor closes.

4.Click the Part that has a Pin-Joint at the center-Point of the Arc

5.Click to close the Command-Manager.

We add for you a Driving-Pulley

STEP 2: Add the Driven-Pulley for Belt #2

1.Machine elements toolbar > Add Pulley

Add Pulley opens in the Command-Manager.

You must select four elements - see images above

1.Click Pin-Joint

2.Click Motion-Path FB

The Part-Editor opens to show the sketch-path of the Belt in the Base-Part

3.Click the radius Dimension of the Arc sketch-element at the Pin-Joint

The Part-Editor closes.

4.Click the Part that has a Pin-Joint at the center-Point of the Arc

5.Click to close the Command-Manager.

We add for you a Driven-Pulley

URL of this topic:
http://mechdesigner.support/index.htm?gst-17_2d-fixed-pulleys-threeshafts-twobelts.htm