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Soundproofing a locomotive

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  • Member since
    April 2017
  • 53 posts
Posted by Mantua Man on Friday, November 17, 2017 6:25 PM

I just finished replacing the universal with the rubber tubing and the result is phenomenal. The locomotive is now only making sound from it's linkage (which is to be expected and adds some realism as no linkage was ever quiet) and the track itself.

I really appreciate all the help you guys have given me,  not many people in my area convert the older locos. I look forward to doing many more conversions with guidance I  the areas needed.

Thanks all!

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Posted by 7j43k on Friday, November 17, 2017 11:35 AM

Mantua Man

I looked at the locomotive more last night, and was able to deduce that it wasnt the first gearbox causing the noise, it was the NWSL 2mm universal drive shaft I had used to reduce tension on the drive axel. I tried to reposition the motor in multiple ways, but the locomotives shell is just small enough so I cant elevate the motor to have a perfect drive line, and I cant rotate the motor width wise because of the rear mounting screw for the cab.

I had suspected this before, but never gave too much thought into it as others say the universals are completely quiet. I am wondering if using a rubber tubing would eliminate this sound, or if I just have to deal with the noise.

 

"Rubber" tubing was used extensively in the olden days:  my Hobbytown diesel came with it, my Tenshodo steam engines came with it (My GN R-2 has been down for years because one of the flex connections started slipping, and it seemed a bit of a bear to get inside to fix it.).

I think you might want to give it a shot.  I think model airplane fuel line is what folks are using now.  It's my IMPRESSION that flex-tubing doesn't do well with an offset--that is: two parallel shafts that are offset.  Of course, as the offset lessens, the shaft run becomes more of a straight line, and use of the flex tubing should be less of a problem.  Anyway, it should be a cheap experiment.

One significant difference between rubber tubing and some of the mechanical universals we use:  the tubing locks in longitudinal and offset movement of the input and output shaft.  As an example:  on my brass steam engines, the motor can be connected to the worm gear reduction assembly on the driver axle directly, and that assembly can be free-floating on the driver axle because the rubber tubing connection will prevent significant rotation.  All hell will break loose if it is replaced by a sliding-joint mechanical universal (the kind that is common in our current diesel models)--the restraint from rotation is no longer there.

Kupla other thoughts:

Perhaps there is a defect in the NWSL universal, and a direct replacement would solve the problem.

or

Perhaps your installation is incorrect, either in design or construction.

Neither of these two possibilities is/are heartwarming.  But what if....

 

 

Ed

 

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Posted by snjroy on Friday, November 17, 2017 10:48 AM

Yes, these u-joints can be noisy. It is a typical problem with diesels. Make sure that the shaft and joint don't rub against anything. On mine, I file the plastic ends in the u-joint that turn the shaft so that they don't stick out and rub against obstacles on the side. They do quiet down after a while, but a heavy angle will always cause some level of noise. Of course, they do need proper lubrication (not too much of course).

Simon

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Posted by Mantua Man on Friday, November 17, 2017 10:31 AM

I looked at the locomotive more last night, and was able to deduce that it wasnt the first gearbox causing the noise, it was the NWSL 2mm universal drive shaft I had used to reduce tension on the drive axel. I tried to reposition the motor in multiple ways, but the locomotives shell is just small enough so I cant elevate the motor to have a perfect drive line, and I cant rotate the motor width wise because of the rear mounting screw for the cab.

I had suspected this before, but never gave too much thought into it as others say the universals are completely quiet. I am wondering if using a rubber tubing would eliminate this sound, or if I just have to deal with the noise.

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    May 2004
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Posted by 7j43k on Thursday, November 16, 2017 10:57 PM

It's very encouraging that the excessive sound is only happening under a certain circumstance.  

One of the ways to lessen noise is with mass dampening.  Basically, you glue a slab of something heavy on.  Or in.  Lead is a GREAT choice.

This may or may not be what you need.  But it is something to keep in mind.

Also worth checking out is the possibility that when the top is put on, it somehow moves or shoves something "out of place".  Or into place, to make the noise.

 

Ed

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Posted by Mantua Man on Thursday, November 16, 2017 8:49 PM

I appreciate the idea, but I've already done it. Without the boiler shell on, the noise is non-existant. With the boiler on, it is heard when going forwards, but not backwards. I do apologize as I should have included these findings in the origional post, but many things slip my mind with all the things I do. Based on this, the shell is probably causing the problem as you said, but this raises some questions. I have already attempted to use the same silicon glue (Which is still the gelatinous mixture) on the cab's bulkhead, the section I needed to cut out to fit the motor and the only part contacting the motor. Despite the added vibration absorber, the sound was exactly the same. Now, the noise could still be coming from the shell, but where on the shell im not sure. I did try to listen and see where the noise was coming from and it seeemed to becoming from the front gear box. I cant confirm this with the shell off as the sound goes away and I cant see the box with the shell on.  It also confuses me why it only makes the sound going forwards and not in reverse.

 

I appreciate all the suggestions and hope we can get to the bottom of this noise.

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Posted by 7j43k on Thursday, November 16, 2017 4:24 PM

It looks like, from the drawings, that this model will run without the top-half-boiler casting installed.

I recommend running the engine both with and without this installed.  IF the noise is much louder with the piece installed, it's being amplified by it.  If so, there are ways to fix that.  I think.

With the piece removed, perhaps your ear can wander around the engine, and find a particular location that the noise is coming from.  If so, that can hint at where your energies should go.  It is, of course, easier to listen when the engine is up on blocks.  This would presume that being up on blocks doesn't affect the noise.

Also, in this condition, you can poke and prod at things to see if the noise is affected.  This, again, can guide you.

Keep in mind that the sound is both "caused" and "emitted".  A moving part will be the cause.  But the sound emission might be elsewhere.  

 

I've only had a couple of old Rivarossi locos (U25C and Dockside).  They both seemed pretty quiet to me.  And I have the impression that that is the general case with Rivarossi.

 

Ed

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Posted by maxman on Thursday, November 16, 2017 4:23 PM

snjroy
Of course, adding DCC sound can mask some of the gear noise.

If the noise is a bad as described, no amount of other background will hide it, unless the background is a band.

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Posted by snjroy on Thursday, November 16, 2017 4:08 PM

Of course, adding DCC sound can mask some of the gear noise.

Simon

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Posted by Mantua Man on Thursday, November 16, 2017 11:07 AM

I see, I'll look onto the locomotive tonight and see if anything needs new grease or modifications. I'll be getting new grease in about a week or so, after which I will report on the progress.

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Posted by selector on Wednesday, November 15, 2017 3:20 PM

If you have done a good job of isolating the motor from anything else on the unit, except for the rapidly rotating driving axle, and you still have a lot of mechanical noise, it's coming from elsewhere.  I would think the first place is the place where the spinning motor drive shaft enters a pillow block or a gear tower, the gear tower itself making noise due to vibrations, gear noise from worn or not-especially-well-matched gears, axles spinning in their trucks, frame noise, amplified noise under the shell, the shell vibrating in concert with mechanical motions or with track vibrations caused by the entire consist....the list is rather lengthy.  So, the motor could be the cause of the noise, but it's not making or emitting noise by itself.

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Posted by RR_Mel on Wednesday, November 15, 2017 11:57 AM

When I re-motor a Rivarossi I use Amazing Goop to glue the motor to the frame.  Goop is very good for noise reduction in the gear train and motor.  I does a good job of absorbing vibration.  You have to clamp or hold the motor in place for over an hour to get past the long setup time of Goop.
 
Normally white Lithium grease will reduce the gear noise in the Rivarossi articulateds.  The Rivarossi grease makes it worse.  
 
EDIT:
 
Replacing the Rivarossi drivelines with NWSL universals will also make a difference with noise.
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
  
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Posted by Anonymous on Wednesday, November 15, 2017 11:51 AM

If you take the motor out and run it outside of the loco, you will find that it runs fairly qietly, with a humming sound. Put it back into the loco, and you will get what you describe as that obnoxious noise. The reason is to be found in the gears. Older locomotives tend to be noisy, especially those with metal gears.

There is little you can do about it, other than keeping the gears well lubed - but don´t overdo it!

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Soundproofing a locomotive
Posted by Mantua Man on Wednesday, November 15, 2017 11:45 AM

Hello All,

If you've seen my post from about a year ago, I did a remotoring job on an old 1969 rivarossi big boy type locomotive. Operation wise the locomotive is running just fine, with smooth and powerful running, but sound wise, it is quite obnoxious. When the locomotive still had its old square motor in it, it made a loud growling noise. Now with a new motor in it, it still makes the sound, but much quieter. it is still noticable when running and I want to make it quieter somehow. When the motor was first installed, I used a premium Silicon glue to hold it in place. The glue never really seemed to dry, always staying in a gelatinous state, but kept the motor in an operational place. I have since attempted to remove the old silicon glue and put new in, but this did not change the result. I also tried applying some of the glue to the bulkhead of the cab, as I thought it was being vibrated by the motor, this also failed to remove the noise. If anyone can please explain why the locomotive is making this sound, I would love the support.

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