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Linear Bearing Failure?

Linear Bearing Failure?

Linear Bearing Failure?

(OP)
I am running an belt-drive elevator with a counterweight and carriage suspended by wire-rope and pulleys.  The counterweight runs on two 1/2" shafts that are four inches apart and has four bearings total (2 on each shaft).  The bearings pairs are 16" apart from each other.  The bearing are plastic and open (N.B. #TW8-OPN) and run on fixed shafts that have been aligned to the correct width.  We are running the elevator at about .7 m/s, the counter weight sees very little load since it is a balance system.

The problem that came up after about 2 months of operation was a loud hammer-like "banging" noise coming from the counterweight as it traveled.  When i inspected the bearings i found one ball to be missing from one circuit in one of the bearings.  Could these bearings prodice such a noise under any conditions???  What else could possibly be creating this noise?  The noise disappeared when the shafts screws were loosened, but came back when aligned and tightened.   any thoughts?

RE: Linear Bearing Failure?

Are you saying you have a plastic ball bearing assembly?
What is (N.B. #TW8-OPN)?
If there is an alignment or unequal tension problem that occurs during actual operation as distinct from when the equipment is not in use then is is easy to imagine plastic bearings becoming warm and flexing excessively.

RE: Linear Bearing Failure?

(OP)
Sorry, the bearing is made by NB, and that is their part number.  It has a plastic housing but stainless balls.  The alignment was made by fixing the shafts when the counterweight was directly over each set of screws, so i am fairly sure the shafts are aligned.

RE: Linear Bearing Failure?

Try and find out what caused one of the balls to go missing.
Sorry I can't be of more help.

RE: Linear Bearing Failure?

Sounds like you had a typical roller ball bearing failure.
Try looking on our website. We supply drop in replacement bearings for most roller ball type. We have a couple of different options to choose from depending on the application.
Check out: www.lm76.com

Hope we can help you.

Patrick

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