Getting Started Tutorials - MechDesigner > Tutorial 17: Belts and Pulleys > Step 17.2: Option 1 - Fixed Pulley Centers

Fixed Pulley Centers - a Belt driven by a Driving-Pulley

This design arrangement has one Driving-Pulley, one Driven-Pulley, and one sketch-path to represent the Belt.

A Driving-Pulley drives the Belt and also a Driven-Pulley.

Notes:

The sketch-path that represents the Belt can be an open or closed sketch-path. Typically, it is a closed sketch-path.

You can control the length of the belt with a Controlling-Dimension - see Control the Length of the Belt

Preparation: Sketch-Path and Pulley Parts

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.

The Motion-Point is difficult to see because it is coincident with the start-Point.

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.

Add Motion-Path FB - Command-Manager

Use Add Pulley

STEP 1: Add the Driving-Pulley

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 the Pin-Joint

5.Click to close the Command-Manager.

We add for you a Driving-Pulley

Notes

The Part that is kinematically-driven (a Rocker, in this case) is the Driving-Pulley.

Belt Speed = Radius of Driving-Pulley × Angular-Velocity of the Driving-Pulley

STEP 2: Add the Driven-Pulley

Do Step 1 again but select the other Pin-Joint, and the Part that is not kinematically-defined.

We add for you a Driven-Pulley

The default colors of a Driven-Pulley and a Driving-Pulley are different.

STEP 3: Edit the Driving Pulley

1.Double-click a Pulley

The Pulley dialog is now open

2.Edit the Number-of-Teeth

3.Close the Pulley dialog

STEP 4: Edit the Driven Pulley