Tagged With "Gearbox"

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Abnormal vibration at gearbox of pump

Ngo Dinh ·
Hi everyone, I have a case with gearbox of the pump which after maintenance (checking gear, backlash, realign gear set and whole train) the gearbox operated with higher vibration with unstable amplitude as file attached. I also open the sign plate at top of gearbox to see the teeth but it is noted that there is no teeth failure. With the input gear with 87 teeth and pinion with 33 teeth, I think that at assembly time, the maintenance staff do wrong phase meshing of teeth contact. So, the...
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Conveyor Gearbox high axial vibration

VANDA BAB ·
Hi every one   iam having problem in Gearbox high axial vibration (High speed I/p shaft)   Conveyor for coal handling in Thermal power station maintaining high axial vibration: (H: 4.0mm/sec    V: ...
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Cooling Tower Gearbox Failures

rgf12 ·
Attached is a report on a recent GB failure on one of our plants cooling tower fan drive gearboxes. It looks to me that the concentration of the failure area on the shaft side of the gear would indicate either a misalignment under load or a general...
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Cross Phase analysis issue

Hossam 2 ·
Problem is in motor if atox mill (insaldo) The free end has a 4xts dominent vibration we have balanced it to reduce one x from 3 to 0.3 mm/s vut still over all value is 5.5mms wiz 4xts sharp  The phase relationship is weired as 180 phase difference between the drive end and non drive end in the vertical direction ..i suspect misalignment problem and the other issue is that no sensors give exact reading across the coupling specially in the gearbox side always give real value in the motor...
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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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Finish Mill Stand Gearbox

Phil2425 ·
I am seeing 1x impacting in waveform data from a gearbox. We have opened the box up to replace a faulty bearing. We inspected the gearsets and did not find any signs of broken or cracked gear teeth. I know that other stand and other mills have a 1x...
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Finish Mill Stand Gearboxes

Phil2425 ·
I am seeing a 1x vibration in our Finish Mill Stand Gearboxes. I know that a broken or cracked gear tooth will cause this issue, however we have opened up a box and did not see ay signs of a cracked or broken gear. Some of our other stands...
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High Vibration peak at 110Hz

Avinash Thawani ·
I am getting a high vibration peak at 110 Hz and it is there in the pump. The pump speed is 68Hz. This is a horizontal pump with a gear box between the motor and pump. Kindly advise what is the cause.
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High horizontal vibration on gearbox

Engr Aamir ·
i have a dynamic separator fan in cement mill area. a motor, gearbox and a fan. gearbox has 2 shafts. i m facing 1x horizontal high vibration 8.5mm/sec and 8mm/sec on shaft 2 DE and NDE side. All other points showing less than 1mm/sec including Motor. also find attachment
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GEARBOX PROBLEM IN STEEL PLANT

dominich.vo ·
Hi all,  I get a problem to monitor a gearbox with variable speed in steel plant. The detail has been described in attachment. the spectrum data shows many of harmonics of turning speed .  So, what's problem with this gearbox and what generates harmonics in spectrum data?   Thanks and regards ! 
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Gearbox Thrust Bearing BPFI due to known high axial load issue and estimation of remaining life of Bearing

Ayaz Ahmed ·
Dear Experts, On 12-Jan-2016 we overhauled a Gear box driving huge axial flow pump (This Pump is the other pump just next to the pump for which I had previously asked a query) through a U-joint coupling. We observed damaged Double Row Spherical Roller Bearing (22232 Bearing installed at free end of Output/ LS shaft @ ~214 rpm) due to High Axial thrust forces on Gear Box from the pump side which is eminent from severe damage on Outer side of Inner row of Spherical rollers. The damage clearly...
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Helical Gearbox failure and sub-synchronous axial vibrations

msmemon ·
Hi , I have seen a number of very useful posts on this forum specially on the gearboxes and would like opinion of members on failure of double helical gearbox with three teeth of compressor side helix found broken during a preventive maintenance inspection. The unit consist of a VFD driven 7 MW motor (1800 RPM), a speed increasing double helical gear and a compressor. The failed Gearbox had operated about 25000 hours since installation. The history of this unit is that it was commissioned in...
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Odd vibration from gearbox

tcvib ·
Have an odd scenario from a reducer,  We have a 151 Hz peak that resembles gearmesh freq.  but gearbox rebuild shop information does not match for that frequency.  gear teeth counts are not conflicting.  Curious if anyone has seen this before.  gearbox is a double reduction, parallel shafts,  1192 input speed, teeth counts are 25 on HS pinion,  Int shaft has 46 teeth on the bull and 20 on the pinion,  Output shaft has 103 teeth.  This is from the...
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Peculiar noise from Gearbox

Nagaraja ·
Came across a gearbox driven by a 400 kw turbine   Turbine input speed: 8700 rpm and bull gear output speed: 1000 rpm   No problem till ouput speed 900 rpm, set will be running smoothly   Once the set crosses 950 to 1000 rpm...the...
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what are the odds?

Nockingroll ·
Conveyor drive pulley with 2 drives fixed speed 4 pole induction motors through fluid couplings and triple reduction gearbox's. drive b the bad actor has had 3 motors in the last 18 months and consistently pulls 40 -80 amps more than A drive (the good...
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Re: what are the odds?

John from PA ·
Originally Posted by Nockingroll: What are the odds the gearbox ratio is not quite what the spec plate says? Although it is possible, in a well designed system I would say it is unlikely. A gear box nameplate ratio may, note the key word "may", vary by as much as ±5% (depending on drive type) Some background information...in 1959, AGMA published information sheet #271.02, "Ratios for Helical and Herringbone Gear Speed Reducers" which listed "standard" ratios based on a (1.5)^0.5 progression.
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Re: what are the odds?

Beatnik ·
It's normal that your 2 drives don't go at the same speed. Conveyor belts can strench and the tension is not equal before your pulley A and between the pulleys. Drive B indeed make all the work but I would bet that it's not because of the ratio level in the gearbox but because of the innapropriate oil level in the fluid couplings. The oil level is what determine the slip and the relative slip determine the load on each drive. The pulley that see a "shorter" belt must have less oil in the...
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Re: what are the odds?

John from PA ·
Originally Posted by Beatnik: Edit: Just realized you said fluid drive and not fluid coupling. if you can change the split/speed/oil level with the actuator instead of changing the oïl level it will be easier to solve the load problem. Originally Posted by Nockingroll: Conveyor drive pulley with 2 drives fixed speed 4 pole induction motors through fluid couplings and triple reduction gearbox's. Actually he does use the term fluid coupling but refers to the machines as "drives" which I...
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Re: what are the odds?

Beatnik ·
Originally Posted by John from PA: Originally Posted by Beatnik: Edit: Just realized you said fluid drive and not fluid coupling. if you can change the split/speed/oil level with the actuator instead of changing the oïl level it will be easier to solve the load problem. Originally Posted by Nockingroll: Conveyor drive pulley with 2 drives fixed speed 4 pole induction motors through fluid couplings and triple reduction gearbox's. Actually he does use the term fluid coupling but refers to the...
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Re: what are the odds?

John from PA ·
Originally Posted by Rusty Cas: It's possible that that the drive with the least slip (less load, higher speed) has a coupling hub somewhere that is slipping on a shaft. I would recommend inspecting all the drive components, looking closely for signs of "red dust" (shrink fits) or sheared off keys. You've missed my favorite expression..."If you hear hoof beats, think horses, not zebras." The OP needs to clarify, perhaps with a sketch but I had in mind an arrangement similar to what I've...
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Re: what are the odds?

Vibe-Rater ·
Originally Posted by Nockingroll: What are the odds the gearbox ratio is not quite what the spec plate says? Hi Nok, I'll keep on calling you Noknroll as per previous forum (what happened?) The ratio is what it is and dictated by the gearteeth. So you should be able to "back engineer" from sufficiently high resolution data to confirm the geartooth numbers. - don't over do it, most go straight for 12800 lines and I think there is such a thing as too much. 6400l should be fine, anyhting more...
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Re: what are the odds?

Nockingroll ·
Thanks for the reply's attached is a rough sketch of the arrangement, this issue has become a focal point, John, I thought I'd read here before that you had stated there are tolerances on the nameplate ratios and you have confirmed it for me, thanks. There are in fact 2 different makers in this arrangement so this line of thought is gaining traction. the slip figures quoted are derived from beat frequencies and not actually strobed due to guarding around the fluid coupling. The B drive is...
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Re: what are the odds?

Vibe-Rater ·
Lots of info coming your way. Some of the stuff I mentioned was already mentioned by others. Apologies for not reading everyone's post in detail and my repeating. rgds
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Re: what are the odds?

Vibe-Rater ·
Nice pic of notebook Nok, with the clarity and colour looks like you might have found said notebook at Mawsons' hut Antarctica. I reckon it is speed matching when it should be current matching as Rusty eluded to. If speed matches that is OK but with possibility of slight differences in slip due to the fluid couplings then transferred toque will be different. Each side should be delivering same torque and the coupling slip is not mechanically predictable it relies on many factors. Proximity...
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Re: what are the odds?

Vibe-Rater ·
Good vid https://www.youtube.com/watch?v=i-2LjlDZU10 Voith a particular brand of fluid coupling (i dont work for them)
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Re: what are the odds?

Gary Stacey ·
Motor B does indeed appear to be working hard as indicated by the degree of slip of the motor and fluid drive. Perhaps a 'tight' gearbox or some other frictional issues on the B side? Gary
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Re: what are the odds?

Danny Harvey ·
I'm assuming that there are backstops on the intermediate shafts similar to a Fromsprag over running clutch. If so, have you verified proper operation?
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Re: what are the odds?

John from PA ·
Originally Posted by Vibe-Rater: Originally Posted by Nockingroll: What are the odds the gearbox ratio is not quite what the spec plate says? The ratio is what it is and dictated by the gearteeth. So you should be able to "back engineer" from sufficiently high resolution data to confirm the geartooth numbers. - don't over do it, most go straight for 12800 lines and I think there is such a thing as too much. 6400l should be fine, anyhting more and "X" stops working nicely. Speedvue input and...
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Re: what are the odds?

Beatnik ·
Our Sumitomo gearboxes on a similar application have a nominal ratio of 22:1 and a real ratio 21.79:1 so it's a possibilty.
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Re: what are the odds?

Vibe-Rater ·
I hear you John. I agree it is not easy back engineering gearboxes especially when the number of stages exceed 2. But... if you accurately measure the input and output (strobe or Speedvue (preferred)) the starting point will give a pretty precise actual ratio. Enough resolution and you should be able to pick out a synchronous harmonic train at in and out which would be the input pinion and output gear. Then work inward from there chasing frequencies from stage to stage until they meet. I...
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Re: what are the odds?

Nockingroll ·
Good timing that you mention that Rusty. Today, rather than rely on rpms and slip derived from vibration spectrums I managed to get a strobe light on the output side of the couplings by crawling under the skid and getting a shot up from underneath, as well as on the motor cooling fan (the fan is routinely done) I can confirm that both motors at time of measurement were doing 1494.1 rpm A coupling output was 1480.9 rpm B coupling output was 1482.9 rpm (nominal. Speed did drift slightly up and...
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Re: what are the odds?

Vibe-Rater ·
Originally Posted by Nockingroll: Good timing that you mention that Rusty. Today, rather than rely on rpms and slip derived from vibration spectrums I managed to get a strobe light on the output side of the couplings by crawling under the skid and getting a shot up from underneath, as well as on the motor cooling fan (the fan is routinely done) I can confirm that both motors at time of measurement were doing 1494.1 rpm A coupling output was 1480.9 rpm B coupling output was 1482.9 rpm...
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Re: what are the odds?

John from PA ·
Originally Posted by Vibe-Rater: And the beauty of intermediate shafts is that they have a pinion and a gear and both tooth counts must be an integer number we know that much. Exactly what is meant by this statement?
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Re: what are the odds?

Vibe-Rater ·
Originally Posted by John from PA: Originally Posted by Vibe-Rater: And the beauty of intermediate shafts is that they have a pinion and a gear and both tooth counts must be an integer number we know that much. Exactly what is meant by this statement? When figuring out geartooth counts from vibration for gearboxes with intermediate shafts (which are often blind) I take a guess at the shaft speed, collect data and then start having a look at the peaks. Assuming that the speed is not correct...
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Re: what are the odds?

John from PA ·
Originally Posted by Vibe-Rater: Originally Posted by John from PA: Originally Posted by Vibe-Rater: And the beauty of intermediate shafts is that they have a pinion and a gear and both tooth counts must be an integer number we know that much. Exactly what is meant by this statement? When the speed is actually correct there should be a peak at pinion tooth count and one at the gear tooth count. Unless they are both integers (using orders off course) the shaft speed can't be correct because a...
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Re: what are the odds?

John from PA ·
Originally Posted by John from PA: Originally Posted by Vibe-Rater: Originally Posted by John from PA: Originally Posted by Vibe-Rater: And the beauty of intermediate shafts is that they have a pinion and a gear and both tooth counts must be an integer number we know that much. Exactly what is meant by this statement? When the speed is actually correct there should be a peak at pinion tooth count and one at the gear tooth count. Unless they are both integers (using orders off course) the...
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Re: what are the odds?

Vibe-Rater ·
Probably semantics I'd say and a good dose of me not explaining well. One I encountered recently. The intermediate shaft after much "playing around" has a 19 tooth pinion and 81 tooth gearwheel. This was determined by tracing the input gearmesh to the intermediate and the same for the output gearmesh as well. When those numbers are combined with input pinion and output gearwheel it gives the exact ratio as measured with Speedvue. If I were to make an incorrect assumption, locate on the...
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Re: what are the odds?

Danny Harvey ·
Given god resolution data I am only occasionally unable to resolve most double reduction gearbox tooth counts.
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Re: what are the odds?

Vibe-Rater ·
Maybe integer multiple then or simply integer. And you're right I mean whole number. If the 81 is incorrectly "set speed" to 82 then going down to the the spectrum 19x won't be an integer anymore. rgds
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Re: what are the odds?

Nockingroll ·
what's all this integer talk? is it some sort of VA slang for into gears
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Re: what are the odds?

Danny Harvey ·
A 2 rpm difference in output speeds is a big deal when both drives are connected to the same pulley.
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Re: what are the odds?

Danny Harvey ·
Even if it is not constant, turning one side of a pulley 2 rpm faster than the other is a problem.
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Re: what are the odds?

Vibe-Rater ·
I had read that a few time before I got it. Funny - to engineers anyway.
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Re: what are the odds?

Danny Harvey ·
I don't think the OP ever answered my question about the presence of backstops.
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Re: what are the odds?

Beatnik ·
One thing we know for sure is that the load is not evenly distributed. I'd have the oïl levels in the fluid couplings checked and look for any leak.
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Re: what are the odds?

John from PA ·
Originally Posted by Danny Harvey: I don't think the OP ever answered my question about the presence of backstops. As near as I can tell from the Rossi North American catalog the U01N design has a backstop and I think the final "S" means solid shaft. See the cross hatched area on the attachment.
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Re: what are the odds?

Nockingroll ·
Sorry John, yes it has solid shaft and a backstop
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Re: Finish Mill Stand Gearbox

John from PA ·
What I see is an overall of 0.0641 in/sec pk, which is not alarming in itself, but I do see a crest factor of slightly over 4. Is this behavior something recent or has this been this way for some time? Any idea is there has been an upward trend of the crest factor? Can you take the gearbox out of service and inspect the teeth using a dye penetrant method? Audibly, does the gearbox have a pronounced "knocking".
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Re: Finish Mill Stand Gearbox

Phil2425 ·
There is not an audible knock. You can just feel a 1x thud when operating. We changed spindle components and it got somewhat better. Just very curious as to what it is.
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Re: Finish Mill Stand Gearbox

Phil2425 ·
The Crest Factor has always ran between 3 - 4.
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