Tagged With "coupling"

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Coupling hub OR shaft run out

vikramdeeps ·
Guys , While measuring run out on hub ,,How to confirm the run out is due to shaft bend OR coupling hub problem?
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fluid coupling mounting

alainraad ·
there is any problem if a fluid coupling is mounted in the wrong direction? the input on the gearbox shaft and the out on the motor? the coupling is flender fludex FAD 297. for me i think that there is no problem, in case that the gearbox shaft can...
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Field Balancing of Pumps

Taha Bin Mahmood, CMRP ·
Guys, I have had some experience in balancing fans and blowers but haven't had any case of field balancing of pumps. I have heard that some people tone down the asset vibration by adding weights on the coupling rather than adding them to the impeller directly as it would be mighty difficult in case of pumps.... will it work and how? what's the procedure?
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flexible coupling run out correction

vikramdeeps ·
Hello , Guys just want to know the allowable run outs for flexible TB woods Dry Flexible spacer couplings ? And where to check it?Any way to correct the radial run out on coupling OR just replaced it?Coupling drawing in attachment
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Motor running in offset from magnetic center

Abhi03 ·
Dear All, We have facing a issue with one HT motor with axial fan load. When we start the motor (consider the motor has stopped in offset from magnetic center) it continues to run in offset up to rated speed (996 RPM) condition without trying to attend magnetic center. However when we reduce the speed bellow 500 RPM it comes to magnetic center and continues to run at magnetic center. The motor is designed with floating bearing and load DE side bearing is axial guide bearing. The motor rotor...
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U-Joint damage

RRS_Dave ·
I have a customer in the food industry that uses a double U-joint for the coupling between a drive motor and dough mixer gearing (actually it looks like the rear end out of a truck). We of course have trouble with water ingress during the sanitary...
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Re: U-Joint damage

John from PA ·
Go to http://www.machineservice.com/...ersal-joint-failure/ for various reasons of brinelling in u-joint yokes (beyond the classic "external" source as cause).
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Re: U-Joint damage

Brian Brzinski ·
Hi RSS_Dave, I have worked in the food industry for several years and have seen this type of failure before. Just a few observations, first, in a wash down area open bearing such as those should be wrapped prior to sanitation or wiped instead of washing. Ingress of sanitation chemicals can cause a breakdown in lubrication that wouldn't necessarily be as obvious as washing the grease out of the bearing. Second, have you checked to make sure that someone didn't accidentally use the wrong...
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Re: U-Joint damage

Dan Timberlake ·
I'm having some difficulty with that pptx file. I was going to search using the forged in numbers to see if the U-joints are name brand, or brand C. Are motor amps or something else being monitored ( and hopefully recorded) during production? Was any maintenance done where large assembly torques were generated on the "other" side of the gear reduction, and perhaps the motor or driveshaft were blocked or jammed to resist the torque? First impression is that it looks like some of the...
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Re: U-Joint damage

John from PA ·
Originally Posted by Dan Timberlake: I'm having some difficulty with that pptx file. I was going to search using the forged in numbers to see if the U-joints are name brand, or brand C. Dan, your problem may be the pptx extension indicating one of the later versions of PowerPoint was used. I've converted the presentation to a PDF. Hopefully that won't present a challenge at your end. By the way, in the journal cross joint (sometimes called the "spider") casting I see "SPR" as well as "sd...
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Re: U-Joint damage

RRS_Dave ·
It is a Spicer joint. As far as grease goes, I think they've finally got a good handle on that. We fought the "food grade" in everything for a while, but with a good RE finally got some grease going in places it was needed. Of course, installation could have been a factor, but this one has been in service for a couple of years, and just now started giving me some indication. As far as hand wiping these things, with literally hundreds or thousands or motors, gearboxes, etc. there is no...
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Re: U-Joint damage

Mark R. ·
Dave, In my high school days I would do this same type of thing to the U-joints in my drive line under my Torino. I always thought it was from hitting the throttle to break the tires loose, you know the sudden shock to the drive line. If your unit doesn't "slam" in I'm not sure what it could be. Could the mixer be locking up or something like that to cause a sudden shock?
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Re: U-Joint damage

RRS_Dave ·
I've never heard of it locking up, it's geared very low. However, this thing does mix from 500 to 1000#'s of dough every 10 minutes or so, and it does go into high speed right at the end for a minute just before dumping. There is a shock I would say every time one of the four bars comes around and squishes into this pile of dough. I am interested now in seeing what one of the other two look like. I am going to see if I can get the RE to pull one of the others and take it apart. I'm not...
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Re: Motor running in offset from magnetic center

Dan Timberlake ·
What make and model of coupling?
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Re: Motor running in offset from magnetic center

edisonindia ·
Looks like your fan is creating an axial thrust higher than the normal magnetic thrust to keep it in magnetic center. As long as it is not creating any vibration issues or abnormal bearing temperature rises, it is not a problem.
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Re: Motor running in offset from magnetic center

electricpete ·
A sleeve bearing motor (uncoupled) has it's own range of motion between two limits. These limits are established by shaft shoulders contacting axial face of the bearing… these surfaces are not designed for continuous axial contact and someitimes are called "thrust bumpers". After you the motor to driven equipment, there is new narrower range of motion established by driven equipment axial thrust bearing, allowing for thrust bearing clearanace, coupling endfloat, and possibly thermal...
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Re: Motor running in offset from magnetic center

electricpete ·
Sorry, I didn't see Edison's comments. I agree with him also. My post added some cautions about loading the thrust bumpers because op doesn't completely explain what the condition is.
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Re: Motor running in offset from magnetic center

Abhi03 ·
@Dan, Its a pin-bush coupling with axial backlash limitation. @EDISIONINDIA Thanks a lot for your feedback. We also though for the axial thrust issue but we are worried that it should not damage the bearing axial collar. Also how do we show customer its from the load side that the issue is coming up and what corrective measures should we take? @ELECTREPETE Thanks for your inputs ELECTRIPETE. We are worried for the same issue that it should not damage the bearing axial collar. Any corrective ...
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Re: Motor running in offset from magnetic center

electricpete ·
A coupling used with a horizontal sleeve bearing motor has to be be able to limit travel beyond a certain point in both directions (in order to prevent motor from hitting thrust bumpers). I haven't heard of pin and bush with axial backlash limitation. Examples of pin and bush couplings that is unsuitable to limit endfloat: http://www.vibispa.com/en/pin-and-bush-couplings.html http://www.industry.siemens.co...ing/Pages/rupex.aspx Do you have more details on your specific pin and bush...
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Re: Motor running in offset from magnetic center

edisonindia ·
Mark the coupled running position on the shaft close to the bearing housing with a marker pen. Stop the motor. Rotate the rotor manually to bring it to the marked running position. Open both side bearing tops and measure the shaft shoulder clearances. A minimum of 2 mm shoulder axial clearance is required to prevent bearing rub though ideal will be equal clearances on both sides of the shoulders for each bearing.
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Re: Motor running in offset from magnetic center

Dan Timberlake ·
Here is a theory that I think explains all the symptoms you have described. In other posts it has been determined that the forces a rotor exerts trying to return to mag center are pretty small. In order for the motor to reach its magnetic center the coupling would have to be VERY slippery or flexible axially. Maybe gear type couplings operating at sufficient angle to be in the hydrodynamic range are slippery enough. Elastomer couplings, machinery mounts, etc, in order to be lubrication-free,...
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Re: Motor running in offset from magnetic center

VibeMan81 ·
I think as ELECTRICPETE points out, its probably not a problem. Dans explanation makes perfect sense to me as well. "A lot is possible. But most of the time a little is sufficient."
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Re: Motor running in offset from magnetic center

Abhi03 ·
@ELECTRICPETE ... coupling is Flender rupex RWN Thank you EDINSONINDIA @DAN.. Thank you DAN.. This sounds convincing we will inspect the coupling and check for any rubbing marks..
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Re: Coupling hub OR shaft run out

electricpete ·
Or check that the sum of rim TIR readings at 12:00 and 6:00 is approx equal to the sum of those at 3:00 and 9:00. If reasonably close, then no mic needed, the hub od is round. But if they differ too much then investigate further with mic.
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Re: Coupling hub OR shaft run out

edisonindia ·
Ovality (?) is different from run-out. You measure the first one with micrometer as mentioned by others here and the second one by turning the shaft. Hub can be oval but still not have a run-out. If you doubt which is causing the run-out, best to remove the hub from the shaft and measure the shaft, hub bore & hub rim individually.
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Re: Coupling hub OR shaft run out

electricpete ·
I agree that ovality is different than runout, but my suggestions is that we can get some info about BOTH from a set of rim TIR readings. Let's say you take dial indicator readings on RIM as rotated every 90 degrees (12:00, 3:00, 6:00, 9:00) with the indicator base mounted stationary. 0, 5, 10, 5. It is 10 mils runout. No indication of ovality. I don't see any benefit to using Mic here. 0, 10, 0, 10. Suggests oval. Followup with mic to confirm.
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Re: Coupling hub OR shaft run out

fburgos ·
measure runout in different locations beginning close to the bearing, if all measurements are high in the same location (12:00 for example) and rising (increments from the bearing to the coupling) it's definitely a bend shaft.
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Re: Coupling hub OR shaft run out

electricpete ·
For rim runout, try an additional measurement on shaft adjacent to coupling hub.
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Re: Coupling hub OR shaft run out

Shurafa ·
Another useful check is done by a micrometer. If the coupling hub's OD is not consistent (e.g. shape is oval), a part of the runout is from the hub. Regards-Ali M. Al-Shurafa
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Re: Coupling hub OR shaft run out

Walt Strong ·
If you are measuring runout at a single location on the coupling hub then there are these possibilities for excessive runout: 1) the hub surface is not in a circular shape 2) the hub bores off-center 3) the shaft is bent I would not state that the shaft is bent without additional measurements. Walt
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Re: Field Balancing of Pumps

ivibr8 ·
Why is it mighty difficult? I've welded correction weights on impellers with no problems. Of course, each pump is different and you should be aware of clearances and location (contact the pump manufacturer) as well as material concerns (weld ability, corrosion, etc.). Adding weight at the coupling to correct an imbalance at the impeller is a recipe for problems in most cases. How sure are you the problem is in the impeller? If the levels are not too high, it may be better to remove the...
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Re: Field Balancing of Pumps

fburgos ·
it might decrease radial vibration by balancig on the coupling, but definetely you adding more couple unbalance, also unbalance force in the driver, is not something i would recomend but theres i know a guy doing this in turbine-generator sets, but you really have to know what youre doing.
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Re: Field Balancing of Pumps

vipul@cmc ·
Yes We can simply do the balancing by adding weight on coupling such like Boiler Feed Pump etc .. it will work very well if there is unbalance in whole assembly of pump.
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Re: Field Balancing of Pumps

fburgos ·
again you really need to know what youre doing, by undestanding the rotor dinamic.
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Re: Field Balancing of Pumps

Dan Timberlake ·
If the coupling was bought "balanced," the dummy/half key used for balancing might be vastly different than the key actually used on the shaft in service, or the half key used when balancing the pump. The result can be significant unbalance when the components are actually assembled. In that case, balance corrections on the hub are "the right thing to do." It is not always easy to tell by looking if that is possibly the problem. I believe there has not been a good consistent standard for...
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Re: Field Balancing of Pumps

fburgos ·
youre talking about a specifical case, and yes balancing the coupling could be the answare, but if the well was welded and not balanced, also the coupling could be a good correction plane for high spot, again you really need to know what youre doing.
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Re: Field Balancing of Pumps

Taha Bin Mahmood, CMRP ·
Okay... The case is hypothetical (just for my knowledge).... What would be the procedure? How would it differ from normal fan balancing in which weights are welded onto the impeller itself?....I understand that adding weight on the coupling may increase amplitude of other frequencies but if the overall vibration levels are under limits... then it should work for the time being...I know some people who are applying this....
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Re: Field Balancing of Pumps

fburgos ·
same as other 1 plane balancing, but it may or may not increase in other directions. the only way to know is to do it
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Re: Field Balancing of Pumps

Dan Timberlake ·
Hi Taha Bin Mahmood, You said ' "I understand that adding weight on the coupling may increase amplitude of other frequencies..." I think I would have said "may increase vibration at other measurement locations ". regards, Dan T.
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Re: Field Balancing of Pumps

Taha Bin Mahmood, CMRP ·
True.... It may increase vibration at other locations but my point was focused on frequencies generated from misalignment, bend etc.... won't it?
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Re: Field Balancing of Pumps

Becar ·
Dan is right. Possible increased vibration on other measurement points. Other frequency amplitudes shouldn't increase. Why would misalignment or bend change beacause of adding the correction weight? It's not logical.
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Re: flexible coupling run out correction

fburgos ·
Runout, where? hub? spacer? its better to be zero. why you whant to change coupling?is there vibration problem, shim pack damage?
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Re: Field Balancing of Pumps

William_C._Foiles ·
I believe there has not been a good consistent standard for dealing with keys over the years. ISO 21940-part 32, A revision of ISO 8821, Mechanical vibration — Balancing — Shaft and fitment key convention, covers this. Basically, this is what was generally practiced in the U.S. Some years ago, the 8821 document had a different method to which some countries switched. That was a mistake, and it may be possible to see some of these mis-balanced components. Luckily, for the most part (by far)...
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Re: Field Balancing of Pumps

electricpete ·
[QUOTE] Why is it mighty difficult? I've welded correction weights on impellers with no problems.[/QUOTE] The key word is "field" balancing and the difficulty is [b]getting to[/b] the impeller (isolating pump from fluid system, disassembling, adding trial weight, reassembling, reestablishing fluid system. Then you're going to take a run, do your calculations and do it all over again? Not likely. Maybe you imagine instead removing the impeller or rotor to the shop for balancing. This might be...
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Re: Field Balancing of Pumps

ivibr8 ·
Pete, good point. Implying its not difficult was wrong. In retrospect, I was was probably thinking of fan impellers and just started typing away. The main thing I was really trying to imply was that trying to correct for imbalance at the coupling may not work out as couple forces would start to act on the system. As others pointed out, vibration at other bearing locations would need to be evaluated. Good catch
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Re: Field Balancing of Pumps

William_C._Foiles ·
A dding weight at the coupling to correct an imbalance at the impeller is a recipe for problems in most cases. How sure are you the problem is in the impeller? If the levels are not too high, it may be better to remove the impeller and shop balance at next maintenance interval (and fix the issue at the same time, e.g. product buildup) Cleaning or repairing a mechanical issue is good, but why do you say that adding weight to the coupling is a recipe for problems in most cases? What problems?
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Re: Field Balancing of Pumps

ivibr8 ·
Quote: "From the thread, I get that it is not known whether the coupling location will work or not work." True. Not knowing anything about the spacing of the impeller to the coupling, I was envisioning a case where a dynamic coupling force could be inadvertently introduced in an attempt to correct for rotor imbalance located in the pump impeller. JP
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Re: Field Balancing of Pumps

William_C._Foiles ·
Quote: "From the thread, I get that it is not known whether the coupling location will work or not work." True. Not knowing anything about the spacing of the impeller to the coupling, I was envisioning a case where a dynamic coupling force could be inadvertently introduced in an attempt to correct for rotor imbalance located in the pump impeller. It can be simple to find the answer to the question, but one has to try. Too often I have seen and even participated in discussions about moral...
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Re: Field Balancing of Pumps

OLI ·
I refused to balance a stainless fan with several of a few centimeter cracks that was starting to warp in a heated environment so we had to do another with mm cracks, at least we drilled stop holes and it went fine so far. It is the only time I balanced things with visible cracks. Olov
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Re: fluid coupling mounting

John from PA ·
Originally Posted by alainraad: there is any problem if a fluid coupling is mounted in the wrong direction? the input on the gearbox shaft and the out on the motor? the coupling is flender fludex FAD 297. for me i think that there is no problem, in case that the gearbox shaft can support the coupling weight. The best advice would be for you to check specifically with the OEM. Having said that, the manual for that drive states "The drive should preferably take place via the hollow shaft (106)...
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