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Grid or Gear Type Couplings

June 28, 2012
(Alignment and Balancing)

When using ‘grid or gear’ type couplings, it is easy to forget to turn your key-ways 180* out, whenever the couplings are massive. Sometimes we just assume that since the couplings are mounted on 6-8” shafts and they weigh so much anyway, that it is not important, but it is. Most of us always remember to lubricate the couplings at the time they are installed, but it is just as important to periodically check these couplings for lubrication especially in hot, wet environments. Making sure your key-ways are turned 180* apart, having the correct key length ( {(A+B)/2}*0.95=Key Length, A=length of ‘cut’ keyway on the shaft, B=length of ‘cut’ keyway on the fitment), proper amount of lube, and good alignment will assure long life of the coupling, not to mention the positive effects of bearing life.

Tip provided by: Chad Tuttle, Vibration Analyst, Republic Paperboard

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Comments (5)

  • Does the phrase "key-ways turned out 180 degrees apart" mean during installation and before assembling the coupling, rotate the driven shaft so its keyway is 180 degrees out of phase with drive shaft keyway? What are the benefits of doing this?
    Tom

    1) Posted 11:54 am, 29 June 2012 by Tom Putnam

  • The purpose for proper key lengths and orientation is to balance the assembly as close as possible. The key length formula is to put as close to a machined key as we can get. The orientation(180 degrees apart)is to offset any residual imbalance.
    The only time we deviate from this procedure is when manufacturers information or matching is given.

    Hope this helps.

    Kenny

    2) Posted 7:25 am, 11 July 2012 by Kenneth Thornton Precision Maintenance instructor-

  • Yes, the phrase "key-ways turned out 180 degrees apart" refers to: the last thing you want to do before actually connecting the driver to the driven is making sure to turn the key-ways 180 degress out of phase to one another. The benefits of doing this is to eliminate an unbalance condition, but this will only happen if the correct key length is used.

    3) Posted 8:22 am, 12 July 2012 by Chad Tuttle

  • Is there a published standard associated with "turning the keys 180 degrees apart"?

    4) Posted 8:20 am, 19 July 2012 by K Miller

  • if the key length is correct is it still necessary to turn keyways 180 apart?

    5) Posted 11:03 am, 26 July 2012 by rickey franks

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