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Genesis GP 38-2 arrived today

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  • Member since
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Posted by Lastspikemike on Tuesday, October 20, 2020 9:16 AM

selector

I saw the post as a two-edged dig, one at himself (which a great many would appreciate as good-natured, if slightly disingenuous), while others would see as the two-edged dig and somewhat less than conciliatory. 

I elected, on my own behalf, to take it as a self-dig, and am glad to see his public admission that he knows he can get under people‘s skin any time it suits him. I also appreciate the embedded “wink”.

Finally, it might be a good time to bury the hatchet, once and for all, act more conciliatory now that we see the wink, and lets get some oil on those dorsal feathers.

 

You saw the wink?

If anyone doesn't see either the wink or the odd time when I forget that my informal writing is somehow offensive feel free to say so. I have zero interest in stirring anything up.

I concede that my informal writing is nowhere near as well thought out as my professional  writing has to be. 

If I seem too assertive (type A?, Diane Keaton has a great line in Annie Hall I'm always reminded of by that phrase " that's one way to say it" ) then I recommend you ignore that post or thread. 

Or just call me out on it and then I'll know and adjust my approach. 

Alyth Yard

Canada

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Posted by Lastspikemike on Tuesday, October 20, 2020 9:22 AM

Worm gears are particularly prone to end thrust, a characteristic exploited in the very clever and pretty much incomprehensible Torsen differential. They also will not reverse under pressure from the spur gear. 

As for bearing tolerance causing noise I wonder if the manufacturer relies on the motor bearings and flywheels to reduce or eliminate worm gear vibration? Out of balance flywheels can cause noise. I've successfully if crudely "machined" flywheels using emery cloth and the locomotive motor as a lathe. The noises caused by out of spec flywheels are lower in frequency.

Alyth Yard

Canada

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  • From: Southern Florida Gulf Coast
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Posted by SeeYou190 on Tuesday, October 20, 2020 10:45 AM

- -
They also will not reverse under pressure from the spur gear. 

Yes they will, just not very well in miniature electric trains.

There was an article about building free rolling locomotives using different pitch worm gears with double helix design in Model Railroader. I have one brass locomotive that will spin the motor through the spur gear when pushed on the track, but you need to press downward for this to happen.

In the industrial world, worm gears being back-driven by the spur gear is very real, and usually dangerous. I do no know of a piece of equipment that is designed to operate this way, but I have seen it happen, most often on material elevators or lifts.

That is why all those extra safety devices are there.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Ringo58 on Tuesday, October 20, 2020 12:01 PM

I have 3 genesis locos ( GP38-2, GP7u, MP15AC and a F9) all 3 are the noisiest locos I own. Besides my P2K gp38 with cracked gears. Even my bachman GP38 is quieter. I do like the detail very much on the otherhand. I'm sure when they have a sound decoder installed when I switch to DCC I will like them more. On my small switching layout I prefer the P2Ks because of how smooth they run at low speeds

  • Member since
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Posted by Spalato68 on Tuesday, October 20, 2020 12:55 PM

Ringo,

you can try to check if the cause is the same as with my F7. To be absolutely sure, you can completely dissasemble one truck, remove worm gear and then assemble truck back. If you connect motor just to to this truck (the other truck must remain without drive from motor), you will either hear that noise you do not like is coming from truck (only motor and worm is rotating, but no gear is driven) or not. If not, then noise cause is somewhere else.

If noise is coming from truck, you can use toothpick to touch worm shaft while rotating - if cause is too big tolerance I explained, you will notice how noise changes while you gently touch worm shaft. You can even try to touch worm shaft without dissasembling the truck, but then this experiment is not precise as it can be.

If cause is too big tolerance, this can be relatively easily rectified. Of course, you must be able to differentiate between normal motor noise and any other noise (I assume your locomotives have standard iron core motor that is used in all Athearn Genesis locomotives - Roco motor, which is good motor but have some noise that is normal for iron core motors, and some of these motors are even noisier due to carbon brushes material, they squeak from time to time). 

And finnaly, here is a short video of my Athearn F7 at slow speed (flat DC), i.e. no decoder installed. I am satisfied, and certain it will run great with sound decoder (probably ESU). 

I have added another video, the same locomotive (now with shell), at higher speed. Squeaking is coming from powerpack potentiometer, it is over 30 years old PIKO made in GDR (German Democratic Republic).

Hrvoje

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Posted by Doughless on Tuesday, October 20, 2020 1:24 PM

Lastspikemike

Worm gears are particularly prone to end thrust, a characteristic exploited in the very clever and pretty much incomprehensible Torsen differential. They also will not reverse under pressure from the spur gear. 

As for bearing tolerance causing noise I wonder if the manufacturer relies on the motor bearings and flywheels to reduce or eliminate worm gear vibration? Out of balance flywheels can cause noise. I've successfully if crudely "machined" flywheels using emery cloth and the locomotive motor as a lathe. The noises caused by out of spec flywheels are lower in frequency.

 

I can't conclude that the worm gear itself being out of tolerance as being the problem.  I know that when adding thrush washers, it makes the fit too tight and the noise worse.

I think the problem could also lie with the flimsy worm gear cover that is the Genesis design.  And replacements are impossible to find, with replacements on the market being the older BB and RTR worm gear cover, which is much more robust.

I have actually seen the worm gear covers snap at the two "legs" that hold the truck into the frame.

IMO, I'm not sure that the redesigned truck of the genesis line is a real advantage over the older designed truck.

- Douglas

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  • From: In the heart of Georgia
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Posted by Doughless on Tuesday, October 20, 2020 2:52 PM

Ringo58

I have 3 genesis locos ( GP38-2, GP7u, MP15AC and a F9) all 3 are the noisiest locos I own. Besides my P2K gp38 with cracked gears. Even my bachman GP38 is quieter. I do like the detail very much on the otherhand. I'm sure when they have a sound decoder installed when I switch to DCC I will like them more. On my small switching layout I prefer the P2Ks because of how smooth they run at low speeds

 

I have 2 GP40-2's, 2 Wisc Southern GP7u (I saw that you had one in the show me thread), 2 BNSF GP7u, 2 CNW GP9Rs, several GP40P-2s and several GP50's.

They all have the same motor and drivetrain design.  I have had issues with the GP7us and the GP40-2s, some of which are brand new releases from August 2020, and were the subject of my swap outs or exchanges, also the LED alignment problems.

Interestingly, all of the GP50-s and GP40P-2s run very quietly and were assembled flawlessley. 

I think it must be about the timing of the batches, and what employees were on vacation when some were assembled.......Confused

- Douglas

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Posted by gmpullman on Tuesday, October 20, 2020 3:59 PM

Doughless
And replacements are impossible to find, —

I can vouch for that. I had to buy the whole replacement truck for about $30 just to get that worm retainer clip!

At last count I have about two-dozen "F" unit Genesis locos. Most of the recent ones run fine out of the box. About half of them I've had to completely "overhaul" the drive line. Another major problem I've run into was the poor pickup issue where the axle tip would not contact the bronze strip in the sideframe effectively insulating the wheel from contacting the pickup strip.

I've had bad motors on at least 3 of them.

 ATH_DC-motor2 by Edmund, on Flickr

Yes, that's melted solder slung off to the inside of the brush housing!

 ATH_DC-motor4 by Edmund, on Flickr

My most recent Genesis engines, SDP40-Fs and SDP-45s and a few others have been running very well.

Cheers, Ed

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Posted by Lastspikemike on Tuesday, October 20, 2020 6:25 PM

Well, I'm just not going to take mine apart. Ignorance is bliss.

I'll pay closer attention to the new GP38-2s, compare to the Athearn Ready to Run GP35 DCC ready and the two Roundhouse AC4400 DCC ready we have, noisewise.

Cant argue with argument that the quality of Proto 2000, or even 1000 is very good, but they are no longer made and never will be again, unless Walthers keeps up the quality. Waiting for Walthers to build something I like.

Alyth Yard

Canada

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