There are many applications that use Pulleys that orbit around a centre.

Dwell Mechanism

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STEP 1: Follow the Steps to Add an Orbiting Pulley

Step 1 is complete

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STEP 2: Add a Trace-Point to the Motion-Point

Step 2 is complete

The Trace-Point is in the image to the left.

We would like the Trace-Point to make an integer number of lobes around the fixed Pulley.

The output, indexing shaft will index one time for each lobe of the Trace-Point.

You may need to add a Gearing FB to make sure the input shaft rotates for each lobe.

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STEP 3: Change the number-of-teeth on each pulley and the centre distance between the pulley centres

 

Now, the Trace-Point shows three lobes that repeat exactly.

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STEP 4: Add a Dyad - RPR

Two Parts, three Joints.

This image shows:

Two new Parts
Two Pin-Joints:

A Pin-Joint joins a Part to the fixed Pulley

A Pin-Joint joins a different Part to the Motion-Point on the Belt.

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Add a Slide-Joint between CAD-Lines of the two new Parts.

Cycle the mechanism.

You can see the output Part indexes then dwells as the input rotates continuously.

Because the Motion-Trace-Points three lobes, the output Part is a three stop indexer.

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