Noisy class 205

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meir
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Noisy class 205

Postby meir » Mon Jun 22, 2020 9:10 pm

Hi guys

I've just purchased a Bachmann Class 205 from a seller on Amazon. During running it in I noticed that it's noisy and sounding "rough" for want of a better word. I've oiled it and run it both analogue and DCC (Bachmann 36-557) which doesn't seem to make a difference. Now this unit is apparently new old stock (nos) so I want to get some opinions on what might be causing the issue before I send it back as I want to be fair to the people who sold it to me and I want to keep it if the issue is resolvable or I'm just being too picky.

The following audio is a bit quiet as I recorded it with my phone a few feet away. The 205 is running at 1/3 to 1/2 speed:

https://soundcloud.com/user-924960616/20200621-145604a

Bigmet
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Re: Noisy class 205

Postby Bigmet » Mon Jun 22, 2020 9:38 pm

Not enough information for a reliable fault diagnosis I am afraid. I have an idea, but need more, here's what you could do.

With no decoder installed, run it at full speed on 12V DC, and chop the power while on straight track - just disconnect it by removing one of the wire connections to the track, or by a switch (but not by using the controller knob/slider) - and measure how far it coasts before stopping and what noise(s) it makes. Report that and we will have more of a clue.

Oh, and welcome to the madhouse. It's a great hobby if you are strong enough.

meir
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Joined: Sun Jun 21, 2020 3:14 pm

Re: Noisy class 205

Postby meir » Mon Jun 22, 2020 10:15 pm

Hi Bigmet

Thanks for replying. As you suggested, I ran the unit on analogue @ 12v and the pulled the power. The loco didn't really coast far and strops within a length of itself - approx 25cm / 10 inches.

[edit] Additionally, the gravelly type noise is much more obvious a mid to low speeds.

Bigmet
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Re: Noisy class 205

Postby Bigmet » Mon Jun 22, 2020 11:49 pm

OK, useful answer, almost certainly drag in the gear train that takes the drive from the worm connected directly to the motor shaft, down to the axles in the bogie. (It should coast smoothly and quietly the best part of a metre, if that part of the mechanism is OK.)

Now the crunch question: have you ever taken this kind of mechanism apart? There should be a diagram in the pack the model came in to guide you.

It may be possible to free it if the drag is from dried grease in the gear train, by feeding in a drop of thin oil from the top (under the worm) and turning over the mechanism, repeating this process multiple times. Messy, and needs a lot of cleaning up after. But if that doesn't work it comes to this: that if you can confidently fiddle around with disassembly and find and free whatever isn't turning freely in the gear train and reassemble the mechanism correctly it is fixable. If you don't feel confident with all that, then best to send it back.

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Ironduke
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Re: Noisy class 205

Postby Ironduke » Tue Jun 23, 2020 3:31 am

Could the loco actually have a sound decoder in it? Maybe what you're hearing is a diesel engine.
Regards
Rob

Bigmet
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Re: Noisy class 205

Postby Bigmet » Tue Jun 23, 2020 8:54 am

Ironduke wrote:Could the loco actually have a sound decoder in it? Maybe what you're hearing is a diesel engine.

See the opening post:
meir wrote:...run it both analogue and DCC (Bachmann 36-557) which doesn't seem to make a difference...

That should mean we are looking at mechanism noise.

RFS
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Re: Noisy class 205

Postby RFS » Tue Jun 23, 2020 9:21 am

Bigmet wrote:OK, useful answer, almost certainly drag in the gear train that takes the drive from the worm connected directly to the motor shaft, down to the axles in the bogie. (It should coast smoothly and quietly the best part of a metre, if that part of the mechanism is OK.)

Now the crunch question: have you ever taken this kind of mechanism apart? There should be a diagram in the pack the model came in to guide you.

It may be possible to free it if the drag is from dried grease in the gear train, by feeding in a drop of thin oil from the top (under the worm) and turning over the mechanism, repeating this process multiple times. Messy, and needs a lot of cleaning up after. But if that doesn't work it comes to this: that if you can confidently fiddle around with disassembly and find and free whatever isn't turning freely in the gear train and reassemble the mechanism correctly it is fixable. If you don't feel confident with all that, then best to send it back.


This is not possible with the 205. The motor is a sealed unit and to get at requires a major dismantling exercise. The bogie contains a set of plastic gears which connect via a shaft to the end of the motor. It is likely that it is these gears that are making the noise and not the motor itself.

You will need to remove the body, and then unscrew the motor bogie at the top of the motor block. You can then prise the bogie frame off to examine the gears but do make sure it's upside down when you do this. If there's dried grease in there you may be able to clean it out and re-lube it.

With the motor bogie removed you can test the motor itself by applying power to the trailer bogie wheels and see when it rotates if it makes a noise or not.

To reassemble you will need to make sure the shaft from the bogie fits into the slot at the end of the motor shaft. Fiddly but not too difficult in the right light.

Also make sure that you cannot manually turn either of the motor bogie wheels: if you can it means the drive pin has fallen out somewhere and only one wheel is powered.
Robert Smith

meir
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Re: Noisy class 205

Postby meir » Tue Jun 23, 2020 7:53 pm

When I run the motor without the motor bogie attached it sounds ok. So, I've run drops of rail modellers oil through it while manually turning the worm gear.
I want to now open the bogie up, but, looking at the diagram, the only way seems to prise it open using a flat bladed screw driver (see the pictures below, the one with the red arrow on it). Is this correct? I tried to do this lightly, but there was no give and I don't want to mangle/break the bogie.

[edit] The wheels to not turn freely - they are definitely driven by the worm screw down through the gears.

20200623_194207 (Custom).jpg


20200623_194212 (Custom).jpg


20200623_195140 (Custom).jpg

RFS
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Re: Noisy class 205

Postby RFS » Tue Jun 23, 2020 9:22 pm

It's a while since I worked on mine, but I believe you are correct - it is a tight clip-fit.
Robert Smith

meir
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Re: Noisy class 205

Postby meir » Tue Jun 23, 2020 10:08 pm

Thanks for confirming that. I've now opened it and this is what I found. It looks ok to me. The grease is not solid and things turn freely :

20200623_215937 (Custom).jpg


Should I clear the grease out? If so what with? I only have rail modellers oil to replace it with.

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SRman
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Re: Noisy class 205

Postby SRman » Wed Jun 24, 2020 3:53 am

While you have it open, I would say yes, clear out the grease.

Another possble source of vibrational noise is the cardan shaft itself, if it is bent or distorted slightly. While you have this all out of the model, check that too.

RFS
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Re: Noisy class 205

Postby RFS » Wed Jun 24, 2020 9:01 am

I would simply remove the excess - did that on one of mine and simply used a cotton wool bud to do that. You need to leave a sufficient amount in to keep the gears lubricated.

The sound does seem like the gears rattling. Perhaps try using the cotton wool bud to extract the excess and smear it over the cogs to make sure it's all properly distributed.
Robert Smith

Bigmet
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Re: Noisy class 205

Postby Bigmet » Wed Jun 24, 2020 10:08 am

Oh yes, that's the 'great gobs of grease' technique that takes a long time to become quiet with running. Thought Bachmann were no longer doing that, some of their earliest centre motor diesels (Peak, Derby type 2) there was practically no airspace around the gear trains!

Remove 90% of it, add a little light oil on the gears, and then give it at least 2 hours running, both directions, and you should get a noticeably quieter mechanism. Once quieted it will go on running with just a very occasional drop of light oil on the worm (for at least 28 years, if my oldest Bach Peak mechanism is a reliable indicator, and that has the axles running in the plastic bogie frame, no neat brass bearing collars.)

Clearly I have just got lucky, have six of this Bachmann bogie drive mechanism design in the Cravens DMU (class 105) and all have been very quiet, as also were a friend's examples of the class 108. But a cheap s/h 105 is coming to me today, perhaps this one will be 'the grauncher'?

meir
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Joined: Sun Jun 21, 2020 3:14 pm

Re: Noisy class 205

Postby meir » Sat Jun 27, 2020 10:06 pm

Update on this. I've ended up having to return the 205. They said they'd send it to Bachmann but refund me, although I'm still interested in having a 205 so have said to let me know if the issue gets sorted out as I may repurchase. I genuinely didn't want to have to return it, but I like to run my locos at slow speeds at time at the noise just throws you out of the moment (whatever that means :p).

On a slightly lighter note I've had a blue & grey class 108 which was similarly noisy, so I opened that one up, degreased and then regreased it and, although not perfect.

Thanks to all of you for you advice - much appreciated.

Bigmet
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Re: Noisy class 205

Postby Bigmet » Mon Jun 29, 2020 12:04 pm

Although overall I rate Bachmann pretty well, past reports suggest that if a model runs reliably, they don't have any great concern for mechanism noise. But I haven't had this problem myself ever, just by report from elsewhere; as I have never yet had to return a noisy Bachmann powered model from just over forty purchases during the past twenty years.

Now specifically, I have seven of these motor units running on my layout in Cravens/class 105 DMU's. All of them very satisfactory, smooth and quiet, as have been the class 108 and Derby lightweight sets that friends have purchased: these all use the same drive unit as the class 205 so it can run quietly. In your shoes I would suggest buying from another source. Chances are you will get a quiet one...


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