Tuesday, April 16, 2013

Synchronous Belt Drives with a BANG!

During the startup of your synchronous drive you may occasionally hear a loud “Bang!” coming from the drive system.  This could be the result of belt tooth jumping, or belt ratcheting which is more prevalent in drives that are under-tensioned or have mismatched tooth forms. Though the installation tension may be correct and sufficient, ratcheting could still occur because of a loss in structural rigidity.  This is due to the fact that belt installation tension calculations do not take into consideration the possible differences in structural rigidity.  Therefore belts which appear correctly tensioned when idle may become under-tensioned when operating, or more specifically during the startup period. 
This belt ratcheting issue is more prominently in direct, across the lines starts in which severe shock loads are introduced to the system during this period.  This severe shock load results in frame deflection which, if the structural rigidity of the drive is inadequate, causes loss in belt tension and potential tooth ratcheting.
One method to determine if the structural rigidity of the system is of a concern is to simply stretch a taught piece of string between the DriveR and DriveN supports in such a manner that any significant movement will result in the string to sag or break.  This of course should be performed with the drive disabled and the proper lock out, tag out procedure followed.  Once the string is set, simply press both the tight and slack side of the belt together and monitor the strings movements.  If significant sag occurs then the structure rigidity should be increased or the belt installation tension will need to be increased above the recommended value.  This increase is used to account for the high startup loading and resist tooth ratcheting given this ratcheting can severely damage the belt and result in decreased belt life and performance. For any additional questions feel free to contact us at ptpasupport@gates.com or 303-744-5800.

No comments:

Post a Comment

Search This Blog