I had a customer ask how long a swivel will last in an unusual application, and I had to sit down and think about how to provide an answer that made sense. In short, the answer is “It depends!”
It depends entirely on how the swivel is maintained and the conditions it’s working in. The bearing manufacturers have a standard calculation that I use to assess a bearing lifespan, comparing the actual applied load to the bearing’s rated load. (Bearings are defined by their Basic Life Rating: the maximum load they can carry at a constant speed so that 90% of a representative sample will reach one million revolutions.)
SKF_bearing
At the Safe Working Load and standard conditions, a swivel’s bearing will last for 1 million revolutions, for example. At one-half the SWL, it will last significantly longer, 8 million revolutions. Both these calculations presume the swivel and grease are not compromised.
In short, the harder you work a swivel, the shorter the lifespan – and the relationship is not linear! Look at the above comparison: one-half the load leads to eight times the revolutions.
The load on the swivel is one factor. The care and maintenance you provide for the equipment is another major factor.
To last for 8 million revolutions, the swivel and its bearing will need lubrication at regular intervals. Since the frequency of maintenance will directly affect the level of reliability, we recommend lubrication after every pullback to keep the grease in the best possible condition. (And a thorough cleaning besides!)
In other news: we’ve had requests for a lengthened version of the Plow Grip Flip video, to fully illustrate the parts order when rebuilding after maintenance. I’ll take a crack at that when we get back from next week’s ICUEE show in Kentucky.
And if there’s anything else you’d like to see, let us know! We’ve got a few ideas for new videos, but I’m sure we could get yours on the list.