Monday, November 17, 2014

Can a good coupling protect against ignored maintenance?

Guest Post: Fred McWilliams, Lovejoy Canada

Early one dark rainy morning in early 2010, I received an irate phone call from the head of production at one of the steel mills I support. He wanted to know why our disc coupling had come off a 250hp motor shaft in a catastrophic failure at 4.00 am that morning.  

Disc Coupling Failure
While, fortunately, no one was injured in the failure, his production has stopped and he wanted me to visit his plant immediately. He was too “hot up”, for me to get any further information. I told him I would come right away.

While driving to the plant, I received a call from a fluid coupling manufacturer's representative, who told me that he had also been summoned, as his fluid coupling had also been part of the failure.

 As Lovejoy Canada supplies this steel mill with SX255-6 Disc coupling assemblies (consisting of 3 hubs and 2 disc packs), that bolt either side of a fluid coupling at this facility, I now could understand why the fluid coupling representative was also involved in this issue. 

Bent Motor ShaftUpon arriving at the job site, both the fluid coupling manufacturer's representative and I were astonished to see the condition of the 250 hp 449T frame 3 ¾” diameter shaft. It was bent almost at a right angle and there was severe heating scars on it.

Upon talking to the maintenance crew, we found out that this particular motor had been making “grinding noises”, for some time and nothing had been done to find out why this was occurring, due to being unable to have Production stopped.

Both the fluid coupling representative and I suggested that the motor be thoroughly examined to see if there was a reason for the bent shaft. It was obvious to us that there had been a failure within the motor that must have caused excessive overheating to the point that the motor shaft had deformed and stopped suddenly, causing the fluid coupling assembly to come off the shaft and break through the coupling guard.
Bent Motor Shaft - Zoom
Lovejoy Canada, the fluid coupling manufacturer, and the motor supplier were asked to replace the damaged parts ASAP so that production could be re-started as quickly as possible.

Lovejoy Canada had our coupling components on our shelf in our Mississauga Ontario warehouse and they were shipped to the customer that afternoon.
Within a couple of days the drive assembly was completed and installed.

A report on the motor found that a rear bearing had seized, causing excessive overheating and deformation of the motor shaft. The new assembly has now been running successfully for over four years, and is “Red Flagged” for regular maintenance. A crucial maintenance/production lesson has also been learned.

While I never did get an apology from the Head of Production for his irate phone call, I did derived a great deal of satisfaction from being able to help him quickly troubleshoot the failure and get his production again.

So to directly answer the subject question, “Can a good coupling protect against ignored maintenance?" The answer is obviously and unfortunately "No". While no equipment will last very long if it is neglected and abused, using high quality products within their designed working envelope (like the Lovejoy SX255-6 disc coupling) will help keep equipment running for a considerable length of time. Again, using quality products should never be an excuse to ignore regular system maintenance.

Fred McWilliam About the Author: Fred McWilliams has served as Lovejoy Canada's Eastern Accounts Manager for well over a decade. To tap into Fred's rich industry knowledge and experience, please contact him through Lovejoy Canada or reach out to him directly on LinkedIn

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