Fixed Pulley Centres : Two or more Pulley Sets

TwoPulleysSets

Use Two Belts to:

Give a larger speed reduction
Reduce total belt span
Wrap the belt more around the DriveR-Pulley.

The image to the left shows

Three shafts
Two belts
Two Pulleys on one shaft.

tog_minus        Step 1:  First Belt

Add Motion-Path of Belt 1 and two Rockers

MD-17-6

PREPARATION IN THE Part-Editor

STEP 1: Edit the Base-Part
STEP 2: Add a sketch-loop to represent the Path of the Belt
STEP 1: Add a Line 1sg

The start-Point of the Line MUST be merged with the centre-Point of the Arc.
[It is easier to Add the Arc, then Drag the Line from the centre of the Arc].

STEP 4: Dimension each Arc1s-red

The exact radius of the Arc is not important.  Edit the Pulley later to enter the number-of-teeth.

See Edit Pulley dialog-box

STEP 5: Close the Part-Editor

MD-17-7

PREPARATION IN Mechanism-Editor

STEP 6: Add a Motion-Path FB2s

Select the sketch-loop that represents the path of the belt.

The Motion-Point shows at the start-Point of the sketch-element you select in the sketch-loop.

MD-17-8

STEP 7: Add one Part3s for each Arc
STEP 8: Add a Pin-Joint4s between a Point in each Part and the centre-Point of an Arc.
STEP 9: Add a Motion-Dimension FB5s to the Part at the Arc you wish to be the Drive Pulley.

There should be one Rocker5s that identifies the axis that will be the Drive Pulley.

[Not shown in the image: You can add a Linear-Motion FB to the Rocker]

There should be one Rotating-Part for each Pulley you will add.

The length of the Parts are not important.

Use Add Pulley

Icon-AddPulley

Click Add Pulley in the Kinematic-elements toolbar

MD-17-4

Add Pulley opens in the Command-Manager. You must use Add Pulley for each Pulley.

Select these four elements for each Pulley. We add a Pulley to the left Arc first.

Refer to the images above to identify the Elements. Select, from top to bottom.

1.The Pin-Joint1s-red
2.The Motion-Path FB2s

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

3.The Dimension3s of the Arc sketch-element

The Part-Editor closes

4.The Part4s joined with a Pin-Joint1s-red at the centre of the Arc.

MechDesigner adds the Pulley.

 

MD-17-9

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

Notes:

A Drive Pulley is given to the Pulley on the same axis as the Rocker.
The Linear Speed of the Belt = Radius of Drive Pulley *Angular Speed of Drive Pulley
The angular speed of the Rocker gives the linear speed to the belt.
This then gives the angular speed to the other Rotating Parts, and the Driven Pulley

tog_minus        Step 2:  Add Second Belt

Add Motion-Path of Belt 2, and two Pulleys

MD-17-40

PREPARATION IN Part-Editor

STEP 1: Edit the Base-Part
STEP 2: Add a different sketch-loop to represent the Path of the second Belt

You must merge the centre-Point1s-red of the Arc for the second belt, with the centre-Point of the Arc for the first Belt.

[Add the Arc first, then use Merge-Point tool in the Geometry toolbar].

STEP 3: You MUST dimension each Arc2s

The exact radius of the Arc is not important. You can edit the number-of-teeth on Pulley later.

See Pulley dialog-box

STEP 4: Close the Part-Editor

MD-17-41

PREPARATION IN Mechanism-Editor

STEP 5: Add a Motion-Path FB3s

Click a sketch-element in the sketch-loop that represents the path of the second belt4s

Step 5 is complete

The Motion-Point shows at the start-Point of the sketch-element you click.

Use Add Pulley

MD-17-42

STEP 6: Add a Pulley

Make the selections for the Command-Manager:

a.Select the Pin-Joint at the centre of the Part Pulley1s-red
b.Select the Motion-Path FB2s
c.Select the Radius dimension of the Arc (the Part-Editor opens to select the Radius of the Arc)3s
d.Select the Part4s

Click OK in the Command-Manager.

The Pulley shows in the graphic-area.

Note: You do not need to add a rotating-Part for the second belt, with a different Pin-Joint. We 're-use' these elements.

MD-17-43

STEP 7: Add a different Pulley at the other end of the sketch-loop

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd