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Re-motoring a Hornby Pacer, with questions.


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Hi,

 

Inspired by the recent article in Model Rail I have started re-motoring a Hornby Pacer using the Branchlines kit.  I have already got stuck once  (see axle will not fit bearings) and given my minimal experience in making things that work, will almost certainly have some more problems that I would appreciate some help with.

 

As well as re-motoring the Pacer, the aim is to fit it with DCC sound too.   Both cars will be motorised and I’m aiming for electric pick-up on all 8 wheels, just one decoder and a speaker in each coach.  That does mean at least 6 wires between the cars for which I will need a 6 pin miniature plug and socket.  I am considering adding lighting, but that may complicate things too much for me.

 

So far I have dismantled both cars and made up the four wheel units, two of which have motors; as seen in the photo below.  One thing concerns me already, is there a danger of the tiny screws that holding the motor in place working loose and falling out. They are so small they would be impossible to find.

 

54B3C49A-FCF5-4ACB-85D3-322380F52DFF.jpeg.62a91adbbf4648b02aba15e12cc732c1.jpeg

 

I will do some simple improvements to the interior.  The Hornby finish is a bit plasticy for my liking. If there is an easy way to get the glazing out so it can be reused I might repaint the unit too. Some kind of gangway between the two cars is really needed too.  However the next job is to fit the axle units and make sure they work.

 

 

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On 21/01/2020 at 20:31, DavidCBroad said:

A spot of Loctite will stop the screws going walk about. Best of luck with 6 wires and the plug, I think I would settle for just two and have separate sound etc on each car.

 
 

Thanks David, that is the sort of advice that is so so helpful.  I’ve put a drop of Locktite on the motor screws as you suggest.

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One step forward and one step back today.  I soldered  wires onto the motors and pushed (but not yet fixed) heat shrink over the solder joints to ensure no shorts.  Taking one unit  I applied  power and nothing happened.  Did the same on the other unit and the same result..  Neither motor shows any sign of life, although the controller says they each draw 0.2 amps.  I’ve tried with a 9v battery too with the same result. I can turn the motors by hand OK.  I’m stumped, any suggestions appreciated.
 

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7 minutes ago, ColinK said:

One step forward and one step back today.  I soldered  wires onto the motors and pushed (but not yet fixed) heat shrink over the solder joints to ensure no shorts.  Taking one unit  I applied  power and nothing happened.  Did the same on the other unit and the same result..  Neither motor shows any sign of life, although the controller says they each draw 0.2 amps.  I’ve tried with a 9v battery too with the same result. I can turn the motors by hand OK.  I’m stumped, any suggestions appreciated.
 

 

Do the axles turn freely before the motor / worm is fitted?

 

If NO, ease the bearings some more.

 

Can you easily turn the wheels by turning the worm (or motor armature) when the motor / worm is fitted?

 

If NO, slacken the motor fixing screws; move the motor / worm away from the gear slightly; and retighten the motor fixing screws. There should be some play between the worm and the gear.

 

Regards,

John Isherwood.

 

If the answ

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The old trick is to slacken the motor screws and put a fag paper betwixt the worm and follower. Then push the motor into mesh, do the screws up and withdraw the paper. Tissue paper does the same sort of job.

 

It does sound like you have them too tightly meshed.

 

Andy G

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If you apply power directly to the motor does it turn, does it buzz, disconnect one wire and turn the controller up to about half and you reconnect the second wire spark does it spark when you apply it to the motor.

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Thanks John,

 

I’ve just checked with an odd result.  Wheels turn OK. Next I removed the screws holding the motor in place So it was no longer meshing with the gears and  put power to it, the motor didn’t turn when I applied power, but it was drawing current.  Trying by hand and it seems like the motor armature itself is stiffer to turn than you would expect.

 

No buzzing or sparking from the motor.

Edited by ColinK
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4 minutes ago, ColinK said:

Thanks John,

 

I’ve just checked with an odd result.  Wheels turn OK. Next I removed the screws holding the motor in place So it was no longer meshing with the gears and  put power to it, the motor didn’t turn when I applied power, but it was drawing current.  Trying by hand and it seems like the motor armature itself is stiffer to turn than you would expect.

 

No buzzing or sparking from the motor.

 

Start with the motors on their own.

 

If they don't turn freely when current is applied, or turn easily when the worm is turned; you've found the problem.

 

How did you fix the worms to the motor shafts?

 

Superglue?

 

Could a trace of superglue have got into the front motor bearing?

 

Ahhhh !!

 

Regards,

John isherwood.

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A long shot, but being open framed, have they picked-up any detritus off the bench? The fixing screws are clearing the armature?

What did you secure the flywheels with? Have you inadvertently forced this substance into the rear bearings? Easily done! Can you spin the flywheels to try and ease it all up a bit? The motors will come back once you get it moving freely, although I have found that this particular motor isn't the most powerful.

 

Andy G

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Hi Colin,

 

I've thought about doing this myself, but have 4 of them, so would be a bit expensive. This is making me re-consider though, mainly for the ride height, as the Hornby model sits much too high compared to other stock. Sorry to see your build isn't going well, it can be very frustrating can't it, it's easy to lose motivation when that happens. I can't hep with this part of the build, but as far as interior lighting goes, I probably wouldn't bother as it'll highlight the flaws in the Hornby interior, especially the raised floor behind the doors, which can be masked by painting the sides black, but lighting would make it more obvious. Painting the floor a dark colour, painting the seats and highlighting the metal handrails on the top of each one (for older liveried versions) do bring it to life a little at least, but I'm not sure it's good enough to want lighting, especially with the large windows.

 

For a gangway, I just used a curved piece of black card, fitted between the sides of the corridor moulding, to fill the gap without interfering with movement on curves. It's not perfect, but does fill the gap, and the two pieces can be touching each other but the cars can still be separated of needed. Just a thought for coupling them, would it be possible to 'double-deck' the new style Hornby coupler, the one with electrical connections used on newer 142s, by putting one on top of the other and using a longer bolt and nut to replace the Hornby pivot? That way you wouldn't need any extra wires or sockets.

Edited by JDW
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Yup, seems to be some loctite has got into the motor bearings.  I've spent a while turning the motors by hand, but they  are still too stiff.  Does that mean I'll have to replace the motors?

 

Another lesson learnt, make sure one power unit works before starting on the second one and making the same mistake twice.

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12 hours ago, ColinK said:

Yup, seems to be some loctite has got into the motor bearings.  I've spent a while turning the motors by hand, but they  are still too stiff.  Does that mean I'll have to replace the motors?

 

Another lesson learnt, make sure one power unit works before starting on the second one and making the same mistake twice.

 

Just a thought - and certainly no guarantees - putting a hot soldering iron on the end of the worm and the flywheel MAY release them, by oxidising the Loctite.

 

Once they're off, you could apply the soldering iron to the motor shaft close to the bearings. IF you are lucky, the heat may destroy the Loctite bond before the it adversely affects the motor itself - or not! Either way, the worst case scenario is that you have to replace the motors.

 

When locking worms and flywheels onto shafts, you can usually do the job by setting the item in its final position and then, using a piece of wire, applying the tiniest touch of adhesive to the interface of the item and shaft furthest away from the motor. The adhesive should enter the bore by capillary action and lock the item to the shaft.

 

Never forget - adhesives are the enemy of all shaft bearings !!

 

Regards,

John Isherwood.

 

 

 

 

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Many thanks John,


I used a cocktail stick to put a drop of Loctite on the end of each shaft then pushed the worm/flywheel on.  As they say, you learn by your mistakes. At least I now know how to do the job properly.

 

I’ve tried the soldering iron trick you suggested.  Good news I managed to get the flywheels off, but bad news the worms will not budge.  Looks like I’ll have to beg, borrow or buy a puller to get the worms off so I can remove the worms and get the motors out, hopefully without damaging the etched chassis unit. The alternative would be to try and cut the motor shaft.  Once I’ve got the motors out, I’ll think about buying replacements (the project is getting quite expensive now).   It would be easier to chuck it all in the bin, but I would really like to complete the job if I can.

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I left both motor units with one of my friends at the model railway club a couple of weeks ago to see if he could get them running. Today I got down to the club to see how he got on.  He had made a little gadget to put in his lathe which used a tyre of a model car to rub against the worm and turn the motor, he ran it for an hour but at the end the motor was still not turning freely.

 

I now have a worm puller and with his help we got the worms off both units which enabled me to remove the motors.  Both were very stiff and very difficult to turn by hand, which does suggest some loctite got in the bearings.  Another club member tried another way of loosening them - put the motor shaft in the chuck of an electric drill, hold the motor and switch the drill on; even that abuse didn't free the motor, although it did get quite hot.  So it looks like all I can do is buy two more motors.:(

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At least you know what the problem is, what to be careful of next time, and that you've tried to repair it before you spend money buying new ones, even if its not much consolation. 

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Progress and partial success.

 

Two replacement motors arrived a while ago and I’ve finally had a bit of time to try fitting them, this time being very careful  with the threadlock.  One motor unit runs fine powered by a 9v battery.  Yippee.

 

The second motor unit isn’t quite right.  If I loosen the two screws holding the motor in place very slightly it runs fine, but if I tighten them fully the motor stops.  I’m guessing the worm is too tightly meshed with the gear on the axle.  I’m thinking the solution is to very very slightly enlarge the screw holes so the motor can be a fraction of a millimetre higher.  There is also a bit of sideplay in the axle, perhaps a few washers would help (where do I get them from?).

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Watching your thread with great interest, as I have some Hornby Pacers which could do with upgrading. Like you, going DCC, with both cars motorised and a single decoder with Back-EMF control.

 

I haven't decided whether to wire the motors in series or parallel - would be interested to hear any thoughts on this.

 

Mike

 

Edited by Mike Buckner
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o The traditional method of meshing worm and wheel setups is to tighten the motor with a cigarette paper between the two. Thin tissue paper would be a useable substitute.

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5 hours ago, ColinK said:

Progress and partial success.

 

Two replacement motors arrived a while ago and I’ve finally had a bit of time to try fitting them, this time being very careful  with the threadlock.  One motor unit runs fine powered by a 9v battery.  Yippee.

 

The second motor unit isn’t quite right.  If I loosen the two screws holding the motor in place very slightly it runs fine, but if I tighten them fully the motor stops.  I’m guessing the worm is too tightly meshed with the gear on the axle.  I’m thinking the solution is to very very slightly enlarge the screw holes so the motor can be a fraction of a millimetre higher.  There is also a bit of sideplay in the axle, perhaps a few washers would help (where do I get them from?).

 

Not sure of the motor design but check that the screw(s) aren't too long and jamming the armature when you tighten them up. I have seen this in the past and it's only fractions that make the difference. Worth checking before you make your holes bigger as that could potentially make it worse.

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Thanks for all your replies, very helpful and appreciated.

 

Here are a couple of close ups, larger than full size.  The two screws holding the motor on place don’t get in the way of the armature (relief), but they are very close to the bearing at the worm end of the motor. That may explain how I got threadloc on the bearings at the first attempt.

 

86DDDA50-D6ED-43B1-AAAE-15FC61F24070.jpeg.85d33eede79dfb99c0d16627e4968ba6.jpeg
 

Now looking from the worm end of the unit that works well.

 

C032CC1E-3C27-4D72-9E8D-7FBA5E25DBE7.jpeg.badeaf79856f79557fd763febe1f29c4.jpeg

 

You can see the two screws that hold the motor in place.  The holes in the frame are the exact size for the screws to go through into the fixing holes in the end of the motor - there is no leeway to enable adjustment.  So for the other power unit where the mesh is too tight, what I think I need to do is remove the two screws and using a tiny file, turn the hole in the frame into a vertical slot so the motor can be moved very slightly upwards, probably no more than 0.5 mm, so the worm and gear are slightly further apart.

 

As to the question about wiring the motors - I didn’t know they could be wired in series - so something else learnt.  What I was planning to do was wire both motors in parallel to a DCC sound chip.  However, we’ll reconsider that when I’m happy both power units run well.

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I just had 20 minutes at the workbench tonight, but more success.  I tackled the motor unit with the mesh too tight.  First I removed the two tiny screws that hold the motor on place. Second I took a very small needle file - a recent purchase from Squires Tools at the Preston exhibition - and made just a few strokes to turn the hole for the screw into a slot.  The slot is only a fraction of a millimetre in the direction away from the axle (you can always file more off, but if you remove too much you can’t put it back) .  I then put a piece of tissue paper between the worm and gear wheel and refitted the two motor retaining screws.  Success, the second motor unit now works properly.

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