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Cosmos Motion and Gear Mates

Question asked by Matthew Leettola on Sep 25, 2008
Latest reply on Oct 1, 2008 by Matthew Leettola

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In a Cosmos Motion simulation I have a shaft set to run at an angular velocity interpolated from a bunch of points I input. I mated another shaft to it using a 1:1 gear ratio but when I check the angular velocity of the second shaft the angular velocity magnitudes don't match.

The shafts are not touching but I don't think that should affect the results.

Update: Our VAR responded and said he found the same bug in the software and has to forward it on as a bug. Will update as I found out more.

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Ian Hogg Sep 26, 2008 11:14 AM
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Hi Matthew,

Would it be possible to upload your input points and/or model?

Depending on the number of points, the results can vary quite significantly. But you are correct that it doesn't matter if the gears physically touch. The 1:1 ratio determines the interaciton.

Thanks,

Ian
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- Basil Gello @ Ian Hogg on Sep 26, 2008 12:07 PM
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  Matt,
  have you tried to check the actual velocity of an input gear? Despite of you have determined the curve, if the bug or a mate affects the rotation, the second gear velocity difference can be the conclusion but not the reason.
  Regards,Basil
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Matthew Leettola Sep 26, 2008 4:31 PM
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Thanks for the responses.

Attached is an example of the problem input gear rotates at a constant 600 deg/s and output rotates at 120 deg/s.

The interpolated data points were .01 sec apart, if that would make a difference, and the data points have a maximum of .3% difference between successive values
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- CosmosMotionGearMate.zip192.3 KB
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- Ian Hogg @ Matthew Leettola on Sep 26, 2008 5:44 PM
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  Hi Matthew,
  
  I initally thought the problem related to you defining the constraint of the second disk with respect to the first (which you shouldn't do if you want to clearly view the realtive gear rotation). You should mate them independantly to ground.
  
  However when I did this, it would not solve (solver will not continue). I will send it in as a bug. I see the same behavior in 2009 as well.
  
  Cheers,
  
  Ian
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  - Matthew Leettola @ Ian Hogg on Oct 1, 2008 7:09 PM
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    If anyone is interested, Cosmos development has found the same problem and assigned it SPR 455129.
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Cosmos Motion and Gear Mates

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