Fixed Pulleys Centres: Pulleys become driven by a Belt
This design arrangement is a little more unusual than the Belt driven by a Pulley.
Physically, the Belt is wrapped around freely rotating Pulleys. The Belt is driven by a motion-values at the input-connector to the Motion-Path FB.
Free Running Pulleys that are driven by a Belt
Preparation : Add Belt-Path and 'Free' Pulleys.
|
| STEP 1: | Edit the Base-Part |
| STEP 2: | Add a closed sketch-chain to represent the Path of the Belt |
Either Hover+Drag or merge the Points at the end of each Line and Arc to give a .
| STEP 3: | You MUST dimension each Arc |
The exact radius of the Arc is not important. However, MechDesigner will use the value to find a Pulley with a radius that is near to its radius and has an integer number-of-teeth.
| STEP 4: | Close the Part-Editor |
|
|
| STEP 5: | Click Add Motion-Path FB in the |
The Command-Manager dialog starts. The selection-box needs you to click a sketch-element.
Click an Arc or a Line in the sketch-loop.
Click OK in the Command-Manager.
The Motion-Point (from the the Motion-Path FB) shows at the start-Point of the sketch-element you select in the sketch-loop.
| STEP 6: | Add a Linear-Motion-Path FB |
Connect the Linear-Motion FB to the Motion-Path FB with a wire.
When you connect a Linear Motion FB directly to a Motion-Path FB, the Motion-Point will move along the total length of the sketch-loop for each .
You can move the Motion-Point with a different motion, with a Motion FB, of course.
|
|
| STEP 7: | Add one Part for each Arc |
The length of each Part is not important.
| STEP 8: | Add a Pin-Joint between the Point in each Part and the centre-Point of an Arc in the sketch-loop |
The Pin-Joint will be the centre of the Pulley rotating shaft.
Note: Usually, join the origin of the Part to the centre-Point of the Arc.
|
Use 'Add Pulley' command
|
You need to use Add Pulley for each Pulley.
Click Add Pulley in the:
- or -
|
|
Add Pulley opens in the Command-Manager.
[Note: Refer to the images in the 'Preparation' section, above, to identify the four elements].
Click, in the graphic-area, the four elements:
The Pin-Joint
The Motion-Path FB
The Part-Editor opens to show the sketch-loop for the Belt.
The Dimension of the Arc sketch-element
The Part-Editor closes.
The Part joined with a Pin-Joint at the centre-Point of the Arc.
Click 'OK' to complete the command
MechDesigner adds the Pulley.
Do Add Pulley again, to add a Pulley to the second Arc and rotating-Part.
|
|
Notes:
| • | The Pulleys are 'Driven-Pulleys'. |
This means their angular-velocity is given by the linear-speed of the Motion-Point along the sketch-loop (Belt) and the radius of the Pulley.
| • | When you add a Pulley, the radius of the Arc changes so that there are an integer number-of-teeth on the Pulley. |
| • | The Parts are horizontal when the is zero. |
| • | Driven Pulleys are Purple |
| • | Edit the number-of-teeth with the Edit Pulley dialog. |
|
|
