Coreless motors - what RTR has them?

[Halvarras]

Well, that was my point - (switch to present tense) if the D600s are produced in the same factory that produces the Dapol Westerns, as the packaging suggests, and no Dapol products have coreless motors, as Wiggy says, then one would not expect the D600s to have coreless motors.

 

However it may well be the case that said factory also produces non-Dapol products which use coreless motors so they were 'on the premises' at the time of D600 development, and for some if not all of the reasons you suggest they were a better option than conventional motors for this model.

[chris251]

On 13/12/2017 at 13:29, NIK said:

I've got the Dapol OO Class 73 and CL121 DMMU and they draw up to 600ma on 12V DC straight out of the box. So I think its unlikely they have coreless motors.

For Dapol models, look on dccsupplies.com, they're Dapol's official spares dealer, so you can find pictures of the motors for certain models, if they're a flat-can type they're likely a 5-pole iron cored motor, if they're cylindrical, they're possibly coreless - coreless motors are a cylindrical can because the static magnets are located in the centre, not around the outside, with bearings in the centre to house the shaft.

 

Both the Dapol 73 and 121 are flat can motors, so likely 5 pole cored, the GWR streamlined railcar is a flat can motor with flywheel too (I had the club one to pieces once to repair a broken pickup wire).

The earlier batch of Heljan Garrets are coreless motors (about 13mm diameter by 30mm long, one motor in each coupled end)

Newer Marklin z-gauge pacifics use coreless motors.

 

 

[mikesndbs]

Hi guys,

 

Bit concerned, does the Heljan Metropolitan loco, 07 and 05 use coreless, they look like a coreless but the instructions say its a 'powerful three pole motor'

Many thanks

[mikesndbs]

On 16/12/2017 at 06:29, NIK said:

Hi,

 

For those worried about the effect of some controllers on locos with coreless motors:

 

For clarification its not feedback that can damage  coreless motors its the frequency of pulses supplied to the motor that's key.

 

As far as I know all feedback controllers send voltage pulses or varying width to the loco and in the gap measure the back EMF (which is related to the speed the motor is spinning at).

 

Coreless motors can have so low an inductance that large currents could flow through the brushes and damage the brushes.

 

This can be got round by sending the voltage pulses very closely spaced (say above 10khz) to the motor. There is sufficient inductance (resistance to change in current) in the motor that the current has not risen to a potentially damaging level before the pulse finishes (the voltage is removed).

 

Because the damage to motors would be expensive obviously folks want to proceed with caution.

 

I haven't yet thought of a way of checking what frequency a feedback controller employs using equipment the average railway modeller would have in their house.

 

If you notice your loco humming slightly at low speeds its probably being powered by a low frequency feedback controller - but that's not a definitive test.

 

Feedback controllers designed before about mid 1970's probably use low frequency but how would one tell when it was designed?.

 

 

Regards

 

Nick

 

Hi Nick

 

Most analog feedback controllers will be employing 100Hz pulses which for coreless is too low.

The other issue is that the PWM signal will use the peak available from the power supply, so 12v maybe, this is a hard hit for coreless designs. I recall KPC used to limit the peak to 9v and very low feedback, this seemed safe enough. 

Pre 90s controllers may well be using 50Hz which is very damaging! 

[melmerby]

3 hours ago, mikesndbs said:

Hi guys,

 

Bit concerned, does the Heljan Metropolitan loco, 07 and 05 use coreless, they look like a coreless but the instructions say its a 'powerful three pole motor'

Many thanks

A typical description of a coreless motor.

More power for a given size & mass.

Coreless motors are normally completely cylindrical as they don't have the typical two magnets outside the armature as in e.g. a Mashima Motor, as the magnet is inside the circular winding.

A coreless motor winding (the magnet sits inside and the drive shaft passes through it):

[NIK]

13 hours ago, mikesndbs said:

Hi guys,

 

Bit concerned, does the Heljan Metropolitan loco, 07 and 05 use coreless, they look like a coreless but the instructions say its a 'powerful three pole motor'

Many thanks

Hi,

 

I've got a Heljan 07 and I can now do an electrical test to tell if a motor is coreless or not but I've only done it on loco motors where the DCC blanking plate is removed so that any extra components are removed from the circuit.

 

I will see how easy it is to get the body off.

 

As far as I know all Heljan's OO diesel and electric locos to date use iron cored motors.

 

Regards

 

Nick

[melmerby]

17 minutes ago, NIK said:

Hi,

 

 I can now do an electrical test to tell if a motor is coreless or not

 

Regards

 

Nick

Interesting.

Exactly how do you do that?

[NIK]

30 minutes ago, melmerby said:

Interesting.

Exactly how do you do that?

Hi,

 

I measured the inductance of the motor - in my case using an LCR meter I bought for model railway RFID development.

 

I found the inductance ranges of coreless and iron cored motors on the internet. They did not overlap so the test should be reliable.

 

Some model railway magazines mention if a new loco/multiple unit has a coreless motor but it is not universal.

 

Regards

 

Nick

 

 

Edited December 31, 2020 by NIK

[Michael Hodgson]

A more useful way of presenting the info in this thread would be as a consolidated listing, tabulating them by scale and manufacturer rather than a long series of postings in random sequence.

 

The reason for wanting the information is presumably that certain controllers tend to damage these motors.  It would be useful to include details of this where known, and also what controllers are safe to use, and also whether there are any issues with any types of DCC decoder.   

 

As far as I am aware the only things I have with coreless motors are a couple of kit built locos with Portescaps.  I can test this by pushing one of them with another on the same piece of track and the back EMF from one is enough to move the other one.  But I suppose that test wouldn't work if the one I push had worm gears.

[melmerby]

1 hour ago, NIK said:

Hi,

 

I measured the inductance of the motor - in my case using an LCR meter I bought for model railway RFID development.

 

I found the inductance ranges of coreless and iron cored motors on the internet. They did not overlap so the test should be reliable.

 

Some model railway magazines mention if a new loco/multiple unit has a coreless motor but it is not universal.

 

Regards

 

Nick

 

 

Hadn't thought of that

I still have a Marconi component bridge left from work so I could try using that to compare the Oxford Rail coreless motor with a similar size Mashima.

[Izzy]

All coreless motors are circular cans, it's inherent as part of the basic design. Heljan have used cored circular can motors in a lot of their 4mm models, I'm not sure but I believe they might be, or may have been at the start, made by Buhler.  I don't think any of their models has been fitted with a coreless just these cored circular motors.

 

This makes deciding whether a motor is cored/coreless less easy if there is no simple visable sign. Although smaller coreless motors use finger brushesbecause of space requirements, (precious metal ones from the makes such as Faulhaber), as the size grows carbon brushes are used for longer life. Faulhaber don't make coreless with fingers above 22mm dia or with brushes below 13mm, (6-22mm fingers/13-38mm brushes). I am not sure about Maxon, Escap, but feel they will be of similar general spec.

 

Just as a matter of interest this is a 22mm dia Faulhaber.

 

 

You will note the 5 segment commutator is just 1mm dia to reduce surface rotational speed and give the maximum finger life possible. The other end is retained with a circlip to prevent pressure on the shaft and damage to the commutator.

 

 

Most cheap coreless don't have these safeguards - and even some expensive makes -  so need using with care and caution when mounting gears on the shafts and using with worm gear drives. I've included a few shots of a cheap 7mm dia coreless for comparison. Hope they may be of help/interest.

 

 

 

 

cheers,

 

Bob

Edited December 31, 2020 by Izzy

[melmerby]

I see even the small one is 5 pole.

The 10mm one fitted to the later Dean Goods is only 3 pole, the earlier iron cored motor fitted to the earlier series was 5 pole

It does have silver "brushes" however

 

 

[stewartingram]

Some magazine reviews quote coreless motors when normal have been used, and vice-versa. Not reliable information.

[Izzy]

'I see even the small one is 5 pole.

The 10mm one fitted to the later Dean Goods is only 3 pole, the earlier iron cored motor fitted to the earlier series was 5 pole'

 

Ah yes, should have said. The small coreless shots are of a Nigel Lawton 8x16mm. Higher spec/build quality than others. Most are 3-pole, those I've had apart such as the Farish 7mm ones. No two have quite the same specs.

[NIK]

Hi,

 

Maybe with the lack of cogging and a reasonable amount of skew winding the three pole coreless might be acceptable for model railway use.

 

Regards

 

Nick

[wiggy1]

The new Bachmann Pannier 94xx is using a core less motor as well.

 

Wiggy.

[wiggy1]

The new Bachmann MR 1532 (P1) is also a core less motor.

 

Wiggy.

[wiggy1]

Bachmann/EFE Beattie Well Tank is core less motor.

 

Wiggy.

Edited January 27, 2021 by wiggy1

[maico]

My Trix German Ho P10 and BR 41 came with Portescaps 12G88 Athlonix coreless motors. It's printed on the housing. A coreless design with precious metal commutation.

Markin Trix charge 45 euros for replacements which come with flwheel and worm. Expensive but actually not to bad as electrical suppliers like RS want £50 for the bare motor...

 

Trix seem to be moving away from coreless though perhaps on cost grounds.  Quality European makes like Maxon and Faulhaber are also expensive. The current BR41 is the same model with a 5 pole can motor fitted. One would hope for a reliable German Bühler 5 pole motor but it's unbranded and could well be Chitat...

 

 

Edited January 27, 2021 by maico

[maico]

Just to follow up what I said about Chinese motors, it is possible to source good 5-pole motors there if you avoid the $1 junk.

I have a Brawa BR216 diesel made 20 years ago in China and it runs great and the die-cast alloy body is fantastic. My recent Hornby B12 also appears to have a decent motor. The Brawa BR06 shown bellow is Chinese made and is the most powerful loco I've owned.

Cheap Chinese coreless designs though are best avoided IMHO...

 

Edited January 27, 2021 by maico

[Rhydgaled]

On 13/12/2017 at 13:04, Steven B said:

Farish:

Standard 5MT

Standard Class 4MT

WD 2-8-0

N Class

Duchess

64xx

LMS 4F

Ivatt 2MT

Jinty

Class 40 (latest model)

 

 

 

I believe the Dapol OO Gauge class 73, 121 and 122 have a coreless motor.

 

Steven B.

Does this apply to the Bachmann (OO gauge) 64xx as well? I'm avoiding coreless motors because I am led to believe by at least one website that my controllers have feedback, but was planning to get a 64xx if Bachmann does another batch of liveries with one I actually would want. Do I need to change my plan to avoid a 64xx (in which case my autocoach would be fictiously worked by a Model Rail 16xx - I'm assuming that they won't be coreless)?

Edited January 28, 2021 by Rhydgaled

[melmerby]

5 minutes ago, Rhydgaled said:

Does this apply to the Bachmann (OO gauge) 64xx as well? I'm avoiding coreless motors because I am led to believe by at least one website that my controllers have feedback, but was planning to get a 64xx if Bachmann does another batch of liveries with one I actually would want. Do I need to change my plan to avoid a 64xx (in which case my autocoach would be fictiously worked by a Model Rail 16xx - I'm assuming that they won't be coreless)?

Feedback isn't the problem per se but low frequency feedback.

If your controller has low frequency feedback then it is advised that you do not use coreless motors, unless it can be turned off.

 

Modern DCC decoders all have feedback as standard but usually can be set to low or high, high being the default and OK for coreless motors, it can often be turned off completely.

[mikesndbs]

13 minutes ago, Rhydgaled said:

Does this apply to the Bachmann (OO gauge) 64xx as well? I'm avoiding coreless motors because I am led to believe by at least one website that my controllers have feedback, but was planning to get a 64xx if Bachmann does another batch of liveries with one I actually would want. Do I need to change my plan to avoid a 64xx (in which case my autocoach would be fictiously worked by a Model Rail 16xx - I'm assuming that they won't be coreless)?

What controller do you have?

[Legend]

I don't think the 64xx is coreless . I don't have feedback controllers , but i do use HF cleaners and there have been no issues with the 64XX.   Its maybe 5 years since the 64XX came out?  I can't remember , it was the last Bachmann loco I bought. More modern Bachmann locos like J72, 1P,94XX seem to have Coreless motors  and it looks like The Precursor will too . I'm not sure about the Rails Caledonian 812 but suspect it will have coreless motor as it looks like Bachmann have switched over . 

 

I would have thought the Model Rail 16xx is more likely to be Coreless . Isn't it made by Rapido for Model Rail ?  Its not on my target list so genuinely don't know . Dibber25 maybe able to help .

 

I think there is a need for clear labelling  where locos may not suit everyones control set up . I am aware I am a bit of a luddite , but then my set up works well on my existing 100+ collection , I'm not really impressed by being forced to change my set up just to run a few new locos .  But its not just me , feedback controllers are fairly widespread . I think the main Hornby HM2000 is feedback . Probably bought by people who are completely unaware of terms like feedback or coreless. So if locos are being made that aren't compatible with these there should really be a big notice saying so , like you get for DCC fitted , ready etc .  

[PMP]

4 hours ago, Rhydgaled said:

Does this apply to the Bachmann (OO gauge) 64xx as well? I'm avoiding coreless motors (snip)

The OO 64xx is not fitted with a coreless motor.

https://albionyard.net/2015/04/02/pannier-capers-the-64xx/