Bearing Noise Bronze Oilite Growling Chatter Rattle

In a genuine hydrodynamic bearing there's an instability known as oil whirl. If it's chatter or rattling as the shaft bounces round a large clearance I think I would call it just that. It might be associated with a resonance.

Precession?

How about."Its going to break soon. very soon."

Karl

FUBAR?

That could've been it, Ned, but I don't remember.

Someone else had asked if nutation could be the term, which is mentioned in the definition of precession.

In the example of the shaft in the lightly worn bearing, the true centerline of the shaft begins to orbit, but not smoothly, hence the chatter-like noise.

Maybe "critical speed" from Machinery's Handbook or "loose" from Murphy's text.

Hul

Wild_Bill wrote:

I dont remember, but early turbocharger development experienced this, and their solution was to let the bearing float in its housing on a film of oil that damped it out.

I recall it as oil swirl, but it's the same thing.

Joe Gwinn

I think that resonance is an aspect of the condition, as in an application with a small motor, where the noise is more likely to occur at a certain speed.

The sizes of motors where I've heard these noises are typically small enough to fit in the palm of a hand.. many are fan motors without side-loading of the output shafts. I've never really been certain if the noises emenate from the output end bearing or the bearing at the opposite end. One might assume that the output end bearing would have more wear than the tail end bearing.

As speed changes take place, there may be a significant change in forces on the motor shaft, similar to making changes in the overhang load.

In the example of fans, at some point the speed of the fan blades (real metal blades more-so) would probbly exhibit a gyro effect, which I think would tend to damp or cancel the noise-causing chatter.

The range of the low frequency growl may be beyond some folks' hearing, but the noises are very noticeable to me.

I've been thinking that the term ended in -ing or -tion.

In the sort of light duty applications where I've encounterd the noise, there is no immediate threat of failure. This condition can continue for years, with the worst factor being slightly reduced performance, and the annoyance of the noise.

The FU part isn't very accurate, other than a deterioration of silent operation.

No the FU is appropriate. Used to work on Teletype ASR33. They were a light duty printer and NCR used them for I/O consol printers on a mainframe. They would wear and rattle and print crap. Was FUed. And they were the crap to rebuild.

Oops, wrong number. They were receive only. RO33.

Be glad they weren't Kleinschmidt printers.

A friend of mine got hold of a genuine Teletype maint manual for the ASR33, and I was blown away (we all were) to discover the power-on lifetime of that model was 2 months. It needed a complete shop rebuild at one month, and was to be scrapped out at 2 months. This would presumably be a situation where the unit was actually printing a fair bit of that time, so in light use they would last 6 months or more.

Well, that DID explain why the computing center needed so DAMN MUCH maintenance on those things. They made a pretty quick decision to move away from ASR33's as remote terminals, and go to video terminals and large shared printers, one per remote facility.

Jon

Yes, turbochargers definitely run above critical speed, and so will spin on an axis through their center of gravity, and to hell with where the center of the shafts were in relation to that. Any attempt to force the rotor to spin on the shaft axis will just break the shaft.

This is a different condition than bearing swirl, but can lead to some of the same problems.

Jon

When I first started in an accounts payable office (1958), they had me checking invoices using a Sunstrand mechanical adding machine. To multiply, you held the add key down for the 1 - 9 cycles then shifted and held the add key again, so to multiply by 99, you added 9 times, shifted and added 9 more times. Anyhow, I was using at least 1 roll of tape per day, and about once per week the print mechanism - vertical element with 10 spring loaded number hammers - would disintegrate, and the machine went on the shelf for the service tech's next visit. My record was eight machines in one week. Incidentally, I have one of these machines, bought new in 1938 downstairs. I should get it out and see if it still works - it was good the last time I used it in 1972! Gerry :-)} London, Canada

In their designed role, they lasted a long time. Get a message, turns on, prints message, turns off. Maybe a minute. Maybe you got 1-2 messages a day. On the Mainframe, they powered up and ran 24/7. We finally got hardened shafts and the rebuilds got fewer.

I bought new KSR 33 and 32 models - the on line using was to be oiled and cleaned out but not trashed. The machines were like tanks. They last a long time. The KSR is keyboard send and receive. A larger unit of the ASR. I also had the paper punch and reader. But most models were that and were called by users ASR. I don't think Teletype would print 60 day life time - these were to make money, not spend it. Clean yes. Trash no.

When dust and grit and ink clog up the flying arms - it comes apart from the top and bottom - the bottom is an oil tray - and was dunked into a

Think the auto shop spray oil cleaning bath. Once cleaned, it remounts and runs. One dips the whole unit in good oil - and put it into service.

I had spare rods and clips - lots of spare this and that - never used.

Consider the 32 and 33 were the beautiful versions of the heavy duty blocks of metal. The heavy ones were in western union stations and weather stations... dumping pages every day for months on end.

Mart> Calif Bill wrote: