plain thrust bearing gurus (large fans)
plain thrust bearing gurus (large fans)
(OP)
I have a situation with limited and need some advice and information. During the investigation of a shaft failure, it appears the owner installed a thrust collar on the outboard end of a shaft and converted the free end bearing to a thrust bearing. The only evidence available (photos) shows thrust collars on the inboard bearing also (where I expected too see them). It has been my experience that long shafts, especially those exposed to high thermal loads only have one thrust bearing to allow the shaft axial movement due to thermal expansion. I am thinking the cause of the failure may have been aggravated by the high stess caused by the trapped shaft. Rotational fatigue, bending, high vibration from shafrt inbalance (bending). The failure was adjacent to the bearing (highest stress area) on the end that had the thrust collar. Questions to all of you intelligent people, Has anyone heard or seen of a dual thrust setup (approximately 20' apart)? Does anyone agree with my theory? Does anyone have any published information that would (1) show the typical arrangement of bearings and thrust bearings clear enough to demonstrate to people with limited experience (i.e. attorneys) or (2) otherwise support or discount my theory? Your assistance would be appreciated.





RE: plain thrust bearing gurus (large fans)
RE: plain thrust bearing gurus (large fans)
KRB
RE: plain thrust bearing gurus (large fans)
RE: plain thrust bearing gurus (large fans)
RE: plain thrust bearing gurus (large fans)
From the 2004 Dodge bearing catalog, DMR 1203-3, page B16-20. "Provision should be made to permit the free movement of shafting endwise due to temperature changes. One bearnig should serve as theanchor bearing to locate the shaft endwise. ALL OTHER BEARINGS SHOULD PERMIT THE SHAFT TO MOVE FREELY ENDWISE."
After that are some examples when that rule can be broken.
From my experience many airhandlers has frames so weak/soft axially that a floating bearing is not required. Whether a particular frame's softness is an elegant design or a lucky strike makes for interesting debate.
Axial restraint killing one or both thrust bearings makes complete sense. The expansion forces being high enough to bow the shaft requires the bearings/frame being MIGHTY DANGED stout, and that is a stretch for me. More info about actual the shaft "failure" would be necessary.
RE: plain thrust bearing gurus (large fans)
RE: plain thrust bearing gurus (large fans)
RE: plain thrust bearing gurus (large fans)
The terminology "thrust collar" sounds to me like a tilting pad (sliding) thrust bearing.
Can the original poster clarify the bearing configuration?
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RE: plain thrust bearing gurus (large fans)
I think now the question is not so straightforward. It could be that thrust bearing on each end of the shaft is acceptable if enough endplay is provided.
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RE: plain thrust bearing gurus (large fans)
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RE: plain thrust bearing gurus (large fans)
The other type has a single groove cut into the shaft (tightly toleranced) where the thrust collar, split in two equal halves and held together by set screws. This is located in the center of the bearing which is called "Fixed" This type will carry more thrust load due to the positive location in the shaft.
RE: plain thrust bearing gurus (large fans)