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Comet Chassis Saga


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Can anyone identify the motor on this chassis please.

I believe it is a Comet chassis for a 28XX   It was built for a friend and I was given the task of fitting couplings and getting it to stay on the track.

Those tasks were reasonably simple, a low hanging nut was causing it to derail .

However it runs absolutely awfully.  It runs well fast, it runs well at a crawl, but it is absolutely gutless and needs full power to get a reasonable train rolling and then rockets away at the first sign of a downhill run.   Is this normal.  Its worse than a Wrenn 8F, much worse than a newish Hornby 28XX.      Tonight it packed up completely. Haven't had a chance to see what's wrong.

Can anyone identify the motor?  looks like it needs another.   Thanks

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DSCN9704.JPG

Edited by DavidCBroad
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The magnet looks misplaced. I think someone has been in there before. It may have lost its magnetism.

 

It doesn't look like an XO4, the brush gear is wrong. Looks more like an Anchorage. You'll have to remove the motor, and see what the attachment to the chassis is - post another picture for comments/suggestions.

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It does look to be either a D11 or D13, the latter being a longer version. I always thought they were pretty gutless and very high reving, the DS10 was better and also had both brushes insulated rather than one live. The TA12 can was in another league and all I really used. 
 

I think a HL box plus any motor will be better......a 60-1 plus Mitsumi would be a good mix.

 

Izzy

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First job is to replace that magnet with a neodymium stack. That will dramatically increase the pulling power.  Also the brass plate by the magnet may have a worn or sticking bearing. Lots of other possibilities, but look at those first.

 

Andy

 

 

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Yes, these motors are quite slim, designed I guess to fit between OO gauge wheelsets. From the look of it the motor is meshed with the gears by soldering the ‘gearbox’ sides to the front of the motor, the brush holder/front bearing part being brass. So getting it out might be a nice little challenge.....       At least it looks like Romford wheels and gears were used to aid this.

 

Izzy

 

ps. From the armature length I would say this was a D11. The D13’s were quite a bit longer IIRC. That’s probably why it’s particularly gutless. They always were from new.

Edited by Izzy
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David

 

Looking at the photo as suggested its an Anchorage D11 or D13, the motor may well be improved by adding a magnet, but that will not solve the issue that it has a motor mount using a low ratio older style set of Romford style gears

 

I have noticed newer Romford gears have smaller Worm gear, apparently makes the gear train more efficient. High Level, Comet and Branchlines all make decent gearboxes, but are designed to fit modern can motors.

 

It might be worth speaking with the likes of Southeastern Finecast to see if they have a better alternative motor mount/gearbox for the D11/D13 series. I have an old DJH GB1 gearbox designed for such motors, you could possibly list a wanted request, though might be worth biting the bullet and getting an appropriate High Level gearbox and motor 

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Agreed. Take out motor and place in bin or on ebay. Take advice from various suppliers/folk on here, especially on the gearbox options. Comet used to do a correct scale set of drawings for motor/gearbox combinations so you could assess the space taken up by them. Replace motor and consider if you could also fit a flywheel as it is a goods engine. Good luck. Glad it isn't actually a chassis problem but a motor problem as I have always found a Comet chassis to be a pretty good product in design and in action.

Good luck

Philth.

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Yes, the bin or ebay is the best place for these KMT motors marketed by Anchoridge Ltd, (M.G. Sharp) and more recently others. They were quality motors but ran far too fast for model railway use at between 32000 and 35000 revs and to be usable the gearing would need to be 80:1 or even more. If used on a exhibition layout with the customary 30 or 40:1 gears and crawling round with a heavy train they overheated very quickly in my experience. I had a few locos with both sizes of these motors and the slow running was so unreliable that some locos had to be used for running through the layout at an unrealistic speed, then CAN motors arrived and WOW what a difference, compared to the above motors the Sagami and Mashima cans ran at half the max speed so the 'usable torque' was in a better place for slower running. The can motors at the time ran at around a max of 10000revs for the 1630 or 17000revs for the 1620. to put this simply, a Stanier Mogul I had couldn't start a train without leaping away at speed once the controller was turned right up whereas once a 1630 can was fitted with the same 40:1 gears the loco could start the train and slowly crawl away realistically and caused many appreciative comments. Top speed was reduced from nearly 200 mph to a much more usable 80mph. The other advantage was in shunting locos, they could crawl about at walking pace, start and stop reliably and of course stay cool.

Just my tuppence worth.

 

Dave Franks

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The big issue with the 1630 cans are that they need fitting above the wheels for clearance, especially with OO, so often a two stage gearbox to gain height, and this isn’t always possible anyway. For a narrow waisted firebox DJH WD 2-8-0 I did to P4 I had to fit the 1630 motor in the tender with the drive under the drag beam to hide it. Which is where the later available flat cans come into play....
 

Izzy

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3 hours ago, hayfield said:

...

It might be worth speaking with the likes of Southeastern Finecast to see if they have a better alternative motor mount/gearbox for the D11/D13 series.

... 

When I bought a chassis kit off SEF it came with a Branchlines gearbox. They're very good, very good indeed.

I too think that the motor in the OP is well worth dumping.

In order to ensure good running it might be worth running a 1/8" reamer through the bearings.

Cheers

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On 15/02/2020 at 12:51, Izzy said:

The big issue with the 1630 cans are that they need fitting above the wheels for clearance, especially with OO, so often a two stage gearbox to gain height, and this isn’t always possible anyway. For a narrow waisted firebox DJH WD 2-8-0 I did to P4 I had to fit the 1630 motor in the tender with the drive under the drag beam to hide it. Which is where the later available flat cans come into play....
 

Izzy

 

Yes, with the later availability of other sizes and flat sided cans equivalent to the 16xx type the open frame type fell out of favour but they still turn up on ebay and also still recommended in the instructions for loco kits like DJH etc. I've remotored many a loco with a can motor and the customer is usually very surprised at the difference in performance.

 

Dave Franks

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  • 1 month later...

It burned its motor out, It was almost brand new, well it took the temper out of the brush springs and seized a brush so I changed it for a longer one. Quite a battle involving drilling the pole piece and tapping it 6BA.

It ran, not well.  Managed to get the body back on, having to make bigger holes in the boiler back plate etc

Then it drove me mad shorting I fiddled with the body filing where the flanges were near the splashers, checked for brake gear fouling wheel tyres,  Pickups shorting / coming loose, etc.    Then it stopped moving completely. there was a vivid orange light behind a wheel.  There was nothing fouling the wheel.  I got it going and the orange went round like a Roman Candle.  Wheels are Romford Markits 28XX wheels.  The Orange glow was between the tyre and the wheel centre reflected off the chassis side. I have never seen anything like it. More than enough to start a fire on a 1 amp H&M controller  See Pics.

 

 

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Edited by DavidCBroad
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As already said chuck the motor and fit a decent gearbox as well.

 

No idea what is happening now, I presume all the drivers are all insulated ? A pick up might be bent ? or it might be part of the motor burning out .

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Yes, another issue with these motors were that only one brush was insulated. As said, best to bin things and get a better motor/gearbox combo. Far less hassle in the long run.

 

Izzy

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You now seem to have a something shorting on the chassis sides, I recently had this issue with a Comet 3F 0-6-0 chassis

 

This latest issue might be caused by a pickup shorting out against the chassis, I presume the pickups are at the bottom of the chassis, either lifting upwards and touching the chassis or pushing inwards again touching the chassis (my problem was the former), but its not in that area.

 

Looking at the photos again it could very well be a brake shoe, either touching a wheel or a metal shard finding its way between the chassis/brake shoe and wheel, just look where the glow is

 

It could be a simple fix, but if the motor is still playing up, if it was me I would strip it down and put it back together, but thoroughly testing each stage and not moving on until each stage is working perfectly. I would assume at some point the motor issue will raise its ugly head again, if you do strip the chassis down perhaps replacing the motor and gearbox for something better

 

 

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13 hours ago, hayfield said:

You now seem to have a something shorting on the chassis sides, I recently had this issue with a Comet 3F 0-6-0 chassis

 

This latest issue might be caused by a pickup shorting out against the chassis, I presume the pickups are at the bottom of the chassis, either lifting upwards and touching the chassis or pushing inwards again touching the chassis (my problem was the former), but its not in that area.

 

Looking at the photos again it could very well be a brake shoe, either touching a wheel or a metal shard finding its way between the chassis/brake shoe and wheel, just look where the glow is

 

It could be a simple fix, but if the motor is still playing up, if it was me I would strip it down and put it back together, but thoroughly testing each stage and not moving on until each stage is working perfectly. I would assume at some point the motor issue will raise its ugly head again, if you do strip the chassis down perhaps replacing the motor and gearbox for something better

 

 

Thanks but it was professionally built within the last 6 months, I have been trying to make it run from freshly completed. It was very sluggish when received.

The fault is not anything rubbing because it goes round in a circular motion like a roman candle

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Sounds like something metallic has got in the insulating layer between the nickel-silver tyre and the Mazak centre. A black mark must show where the burning was occurring. Try clearing it with something pointed and then check with a meter preferably, or wires from the power supply to each side of the wheel insulation.

When you are absolutely certain the damaged insulation is clear of burnt material, fill it with epoxy adhesive.

 

Jim

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8 hours ago, DavidCBroad said:

Thanks but it was professionally built within the last 6 months, I have been trying to make it run from freshly completed. It was very sluggish when received.

The fault is not anything rubbing because it goes round in a circular motion like a roman candle

 

David

 

Sorry I was looking at the photo and failed to read the description fully

 

I seem to remember reading/being told the insulating layer is paper, strange one as I have never come across this issue before

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16 hours ago, DavidCBroad said:

Thanks but it was professionally built within the last 6 months, I have been trying to make it run from freshly completed. It was very sluggish when received.

The fault is not anything rubbing because it goes round in a circular motion like a roman candle

If it was built that recently, don't do anything more - return it as faulty.

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8 hours ago, Tim V said:

If it was built that recently, don't do anything more - return it as faulty.

 

In the circumstances, good advice. 

 

The advice was given based on what I would have done. 

I would find it easier to fix the item than to repackage and write out a letter explaining the problem.

 

However I appreciate that for many (perhaps most?) people this is not the case.

 

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