Fixed Pulley Centers: Belt becomes driven by a DriveR Pulley
This design arrangement is very common : there is one Driven Pulley.
The belt becomes driven by the Driven-Pulley. The other Pulleys become driven, via the Belt.
Preparation: Sketch-Loop and the Pulleys
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| STEP 1: | Edit the Base-Part |
| STEP 2: | Add a sketch-loop to represent the Path of the Belt |
In this example, the sketch-loop has two Arcs and two Lines.
| STEP 3: | Add a Line  and merge the start-Point with centre-point of the Arc. |
It is easier to Add the Arc, then Hover+Drag the Line to merge it with the centre of the Arc.
| STEP 4: | You MUST dimension each Arc |
The exact radius of the Arc is not important. MechDesigner uses the dimension to add a Pulley with an integer number-of-teeth and near to the radius. (you can edit the number-of-teeth later).
| STEP 5: | Close the Part-Editor |
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| STEP 6: | Add a Motion-Path FB |
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.
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| STEP 7: | Add one Part for each Arc |
The length of the Parts is not important.
| STEP 8: | Add a Pin-Joint between a Point in each Part and the centre-Point of an Arc. |
Usually, use the origin of each Part for the Pin-Joint.
| STEP 9: | Add a Motion-Dimension FB to the Part you wish to be the Drive Pulley. |
There should be one kinematically-defined Part that identifies the axis that will be the Drive Pulley. In this case, it is a Rocker.
[Not shown in the image: You can add a Linear-Motion FB to the Motion-Dimension FB]
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Use Add Pulley
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You must use Add Pulley for each Pulley.
Click Add Pulley
- or -
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Add Pulley opens in the Command-Manager.
Click, in the graphic-area, the four elements from top to bottom.
See 'Preparation' images to identify the elements: :
The Pin-Joint
The Motion-Path FB
The Part-Editor opens to show the sketch-loop to which you added the Motion-Path FB.
The Dimension of the Arc sketch-element
The Part-Editor closes.
The Part joined with a Pin-Joint at the centre of the Arc.
Click 'OK' to complete the command.
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MechDesigner adds the Pulley.
Do Add Pulley again, to add a Pulley to the right-hand Arc and Part.
Notes:
| • | A Drive-Pulley is given to the Pulley on the same axis as the kinematically-driven Part (the Rocker, in this case). |
| • | Belt Speed = Radius of Drive-Pulley * Angular-Velocity of the Drive-Pulley |
| • | The Belt-Speed gives the angular-velocity of the Driven-Pulleys |
| • | The Drive Pulley can transmit a Torque and tension to the Belt |
| • | You can edit the number-of-teeth with the Edit Pulley dialog. |
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