Another dead motor, and fixed

[Rallymatt]

The 3 pole motors on the early TT:120 locos are not very robust to say the least. 2 have died in past 2 weeks on A4’s. One is back at Hornby who are being excellent at replacing them but it’s not a long term solution. Thanks to some of the digging around from others I think @Too Tall and @DJBDoug to name 2, I decided to dig in a bit deeper. I mentioned the coreless motors that Peters Spares had in but I needed a longer pin for the gear puller to remove the worm gear from O/E motor. 
I have done a ‘endcap & brush swap’ and it’s worked. It’s a bit delicate as parts are small but not that difficult. Remove body, motor top mount, I’d recommend pulling the tender plug so decoders etc are fully isolated, de-solder the motor wires, remember to mark the live feed wire. Undo the metal can crimp on the motors, carefully withdraw the new end cap and contacts, it stays as one assembly. Ensure cap is oriented correctly and gently locate while turning the motor shaft. It should seat easily. Re crimp, check the positive (so loco goes forwards properly) re solder motor feed/return wires, re fit the heat shrink insulation & Test, and re assemble. 
The motors are cheap but the bit you need is the contacts in the end cap. Swapping over this means you don’t have to swap worm gear over, if that’s a bit harder for you. This is cheaper and easier than posting back to Hornby. 
Pic of the burnt out contacts that act as brushes 

Edited July 15 by Rallymatt

[DJBDoug]

A cheap £1.50 fix . How much usage was on the failed brushes ? 

[Rallymatt]

This is WW and was a warranty replacement, it logged 35 running hours, Silver King is at Hornby and logged 31 hours. 
The end cap swap should be in the realms of anyone who can use a soldering iron. 
I have longer pins for my gear puller coming from Sven at TramFabrique and will test how they get on with brass worm gear. It would be great if he could do one of his super motor upgrade kits, really top chap and proper enthusiast. 

[Silver Fox 17]

1 hour ago, Rallymatt said:

This is WW and was a warranty replacement, it logged 35 running hours, Silver King is at Hornby and logged 31 hours. 

When the brush/worn out motor discussion started early 2023 it was stated the motors should last 100 hours and when I said that is not long others said it is a long time and would take ages to get to that stage.

This looks like it is approx 1/3 what was expected and is not too good in my opinion although others may think it is a perfectly acceptable time scale.

[Rallymatt]

Garry, The 100 hour mark is low! I know I have seen/heard Hornby stating they would expect 300hour life from these motors at least. They clearly are not capable of anything like it. People such as Nick @ntpntpntp who has years of experience in N where these type of motors have been used has always said the design is not a long life one. 
If you look at the chassis of the A1/3/4 and the 08, there is a slot where it looks suspiciously like a flywheel was intended to go. Were these models intended to have a different motor set up? In announcing the J50, Carl did say although a 3 pole motor is planned, it would have carbon brushes and I think that says it all. 
The O/E motor runs well when it’s well but has an incredibly short service life, it’s a $1 motor. 
I pulled the motor apart from my very expensive failed Roco BR108, it’s exactly the same failure but all the fingers on the positive wipers have burnt away in 2 hours! 
At least we now have some options to fix at home although it’s not ideal. 

Edited July 15 by Rallymatt

[Silver Fox 17]

7 minutes ago, Rallymatt said:

I pulled the motor apart from my very expensive failed Roco BR108, it’s exactly the same failure but all the fingers on the positive wipers have burnt away in 2 hours!

The motors are certainly being a let down and I can say your Roco 2 hours was good compared to my Heljan Garratt that lasted 30 minutes and as by that time many, many others had failed I took the motor apart to find the commutator had actually melted, brushes were wipers too. Heljan did send replacement motors out but due to many other issues I got rid.

As you say Martyn has said the J50 will have brushes so let's hope it is a far better design than these.

I do wonder now if Hornby were having motor burn outs on their demonstration layouts when a few times trains were not moving or completely missing from the track the following day.

[Generic Hornby Username]

3 minutes ago, Silver Fox 17 said:

I do wonder now if Hornby were having motor burn outs on their demonstration layouts when a few times trains were not moving or completely missing from the track the following day.

Let’s hope so! This would actually be good for all of us. If Hornby’s team experiences the burnouts, they’d realize the inadequacy first hand. That’s one way to get the head of brand’s attention!

[ntpntpntp]

When the small coreless motors started appearing in N gauge locos there was some forum chatter about similarly low 100 hour lifespans.   I seem to recall one or two people ran a couple of them to death (might even have been Sven @ TramFabriek) and they certainly exceeded the 100 hours, but whether or not that was under a reasonable load I don't recall.   Coreless motors come in different levels of quality just like these can motors. For example Faulhaber have been supplying top quality coreless motors for a long time and they've been popular with loco builders.

Bottom line is these I don't think these cheap motors are anywhere near the quality and robustness we expected in the high quality locos we bought a couple of decades ago.  Cheapo 0-4-0Ts and similar had cheap motors, but not "proper" models 🙂  

Edited July 15 by ntpntpntp

[Too Tall]

@Rallymatt Just to clarify, are you replacing the end caps with the  N20's from ebay ? If so do they have carbon brushes instead of the Hornby ones metal tangs ? (for want of a better word !), or is it just a temporary fix for another 30 hours runtime and once you have the suitable pinset you aim to replace the motors with the coreless kits ?

 

[Rallymatt]

Spot on TT, the end caps of the cheap eBay N20 motors have the same wiper contact arrangement as O/E. so potentially this just a stop gap until they wear out. However at £1.50 or so for 30 hours it’s cheaper than posting an out of warranty loco back to Hornby. 
The plan is though to swap to a coreless one asap because I am curious to how the running changes if at all. 
It is disappointing that such an integral part of a model is so poor quality. It’s not just a Hornby thing, it’s right across the board as others have quoted. 
Surely it’s not beyond the wit of man, quarter the way through 21st century to make a small well performing and reliable motor. I doubt NASA use these, not even in a pencil sharpener 😳

[Silver Fox 17]

46 minutes ago, Rallymatt said:

. I doubt NASA use these, 

If they did they would have to put a few spares in to allow them to get back lol

[Fishmanoz]

The design implications in this thread indicate a very significant issue in the making for the early locos.  I trust it is not beyond the wit of the design team to have a retrofit solution with longer life.  In its absence, the naysayers will have a field day.

[Rallymatt]

That Fishy, is an absolute concern. I must stress that Hornby do look to repair all failed locos currently and that is admirable and appreciated, but for how long and with what? 

[Too Tall]

Obviously the design can be improved, or replacements with a longer lifetime sourced, it comes down to costs I imagine. I think I recall something in one interview with one of the Hornby guys, that they considered coreless, but were concerned about its rep for not playing nicely with certain controllers.

Still to this day there are people who are wary of them when you watch reviews, but I think by and large they can be very good if you get a good quality ones, they may just need some tweaks for CV settings on DCC. I don't pretend to understand this, but something to do with back emf I believe.

Does the 5 pole motor in the Duchess have brushes or a similar set up to these, does anyone know ?

 

[What About The Bee]

By March of 2024, the Financial report indicated ~12,000 TT locomotives had been sold. 

The bit of good news on that number is that its significant enough to catch the attention of any motor manufacturer, especially if we assume most or all of the 12,000 will have equally short lives.

Do all the TT locomotives use the same motor?

Bee

[Too Tall]

28 minutes ago, What About The Bee said:

Do all the TT locomotives use the same motor?

Bee

The Duchess, the Class 43 and Class 50 have different motors I believe.

Edited July 16 by Too Tall
Corrected myself !

[Silver Fox 17]

40 minutes ago, What About The Bee said:

Do all the TT locomotives use the same motor?

The A1/3/4 and 08 had small 3 pole motors. The Duchess a larger 5 pole skew wound so totally different. No idea what the HST and 50 is as never looked inside the chassis housing.

[Kenneth-365689]

Would it be possible for one (or more) of the more technically educated forum members, who have a knowledge and understanding of the motors currently fitted in the TT120 range, to post a listing of these motors together with a list of possible replacements. Having read the previous listings in this thread, it seems to be a fact of life that these motors will fail at some point. As I, and I'm sure many others, have very limited technical knowledge, knowing what replacements to source and where to source them from would be invaluable. It would, if nothing else, reduce my anxiety levels which are at the moment a tad higher than I would like them to be 🙄😹. Thanks. Ken. 

[Leslie-359394]

Kenneth-365689, I totally agree with your suggestion. I have no technical experience on this subject and would welcome the help from the more technically minded members of this community.

[Rallymatt]

The 12,000 TT:120 locos mentioned in the annual reports would have almost all had the 3pole can motor that I started the thread addressing. 
Class 43 (HST), Class 50 and Duchess all have a skew wound 5 pole motor with dual flywheels in 43 & 50 perhaps @Silver Fox 17 can confirm status of Princess, I haven’t opened mine up yet. These locos were largely delivered after the year end so won’t have been included in the 12,000 (4000 via sets, 8000 via additional sales) Of course the 3 pole motor models continue to sell too. 
Just to set people’s minds at rest, although it’s pretty clear these motors will fail and in what many of us feel is a very short time, Hornby to my knowledge have never refused to replace a motor in TT:120. The oldest locos are out of warranty and Hornby continues to support those models. 
To further reduce anxiety we also have some home fixes available, It looks like a video on this, swapping the motor end cap might be a good place to start, I now need a dead loco! 🤣! 

@DJBDoug has successfully demonstrated that the inexpensive eBay N20 (this is purely a size designation not a quality rating) will transfer to a loco, in his case 08 shunter. The running speeds are slightly different at different voltages but that shouldn’t be an issue in operating the model. Those motors are the ones I used to salvage a new motor end cap from. Using the whole motor or replacing with a currently available coreless motor and a 3D printed adapter case will require swapping the worm drive from the shaft of the old motor to whichever replacement you use. That will require some tools, around £20 from Sven at Tramfabrique (who sponsors Jenny Kirk, Sven is a well respected model engineer) 

Please, no one get worried that this will render models useless, difficult or expensive to repair; it won’t. It was my own concerns that led me to pursuing this. 

Ultimately the best fix would be a direct replacement from Hornby with a suitably upgraded motor to address the frailty of the one in question. Supplied to customers with a worm drive installed or installed via their service centre. The forthcoming J50 will have a small 3 pole motor but critically it will have traditional carbon brushes (according to Carl) if that motor has the same case dimensions as the current N20 this could be part of the long term solution. 
Run your locos, don’t worry, it’s all fixable 😁👍

 

 

[Silver Fox 17]

46 minutes ago, Rallymatt said:

Class 43 (HST), Class 50 and Duchess all have a skew wound 5 pole motor with dual flywheels in 43 & 50 perhaps @Silver Fox 17 can confirm status of Princess, I haven’t opened mine up yet.

Is this what you mean Matt?

[Rallymatt]

Thanks Garry, hard to determine if the motor has carbon brushes unless that plate of the rear is how they are loaded in. The gear tower looks too small diameter to house a flywheel, that would be just the worm drive. 

Edited July 16 by Rallymatt

[Silver Fox 17]

7 minutes ago, Rallymatt said:

Thanks Garry, hard to determine if the motor has carbon brushes unless that plate of the rear is how they are loaded in. The gear tower looks too small diameter to house what you would expect a flywheel to look like. 

There is no flywheel in Matt, I know that from doing the Baltic tank as when grinding the rear chassis I had not realised but ground away the rear mount and the motor slipped out backwards.

This bracket I think was just to hold the motor in as far as I can remember. 

 

Edited July 16 by Silver Fox 17

[ntpntpntp]

Looks like just another can motor with "no user-serviceable parts" as they used to put on many household items 🙂 

[Porfuera]

5 hours ago, Too Tall said:

I think I recall something in one interview with one of the Hornby guys, that they considered coreless, but were concerned about its rep for not playing nicely with certain controllers.

I may be wrong here but my recollection of that interview (it was Carl, I think) is that it was Hornby's own train set controller that was the problem and the reason that they did not choose coreless motors for TT:120. It is a pity that they did not take the opportunity to redesign their controller but perhaps they already had too many sitting in the warehouse/factory.

Someone on RMweb gave an explanation as to why their controllers are so bad and I've quoted part of it below. I don't have the technical know-how to confirm whether it is correct but it certainly coincides with my own experience in that the Hornby controller is horribly buzzy (especially at low speed) and because of this I never use it and instead I always use a Bachmann N Gauge controller when running in TT:120 locos on DC:

"The Hornby Controllers use Pulse Width Modulation (PWM) which basically means instead of the speed being controlled by a constant voltage sent to the rails, it is controlled by pulses of maximum voltage with zero in between. They then adjust the length of the maximum compared with the length of the zero volt signal, which (kind of) averages the peaks and zeros to control the speed.  Unfortunately this will make a DC motor buzz . This effect is much more noticeable at low speed, then as the speed increases the buzz will become much  less noticeable."

The link to the post and the rest of the thread is here.

It makes me wonder whether Hornby would ever go to coreless motors for TT:120 because there must be a lot of beginners out there using the Hornby controller that is supplied with the DC sets and if that controller doesn't work well with coreless motors then presumably they would get a lot of complaints. In any event I think I read somewhere (possibly on this forum) that coreless motors are better for high-speed applications and can also suffer from heat buildup because they don't have an iron core to help absorb/dissipate the heat. Again I don't have any technical knowledge and I may be remembering wrongly so I'm happy to be corrected!