Slow Running Hornby Grange

[BMacdermott]

Hello everyone

 

I have three Hornby Granges from the original release which hadn't been used for some weeks (although not months).

 

Two run fine and are perfectly in 'performance context' with other locos - however, one has simply 'gone slow'. It will run for maybe 10 seconds at 'freight train speed', then slowly stop and not respond to the controller. If I leave it for five seconds, it will run exactly as previously.

 

All wires etc have been checked.

 

Any ideas? Suggestions?

 

Brian

[cypherman]

Hi,

Sounds like it is overheating. Gets hot and slows down, Cools and starts over again. Or the motor is just failing.

Edited May 23, 2021 by cypherman

[BMacdermott]

Hello cypherman

 

I haven't detected any overheating. When the loco is running, it is as smooth as silk - although it feels that it has had a 'speed limiter' fitted. 

 

Brian

[The Johnster]

 

 

I'd suggest it's time for a bit of fault finding by process of elimination.  First job, if you use DCC, is to remove the chip and run the loco from a DC power source to see if the problem lies with the chip. If it runs ok on DC, you now know the problem is in the chip.  I can't help you with DCC as I know next to nothing about it, but there will be someone along shortly who can, no doubt! 

 

If the loco still runs slow on the DC supply, remove the motor from it's mount and apply current to it.  If it still runs slowly then you have established that the problem is with the motor and not anything to do with problems on the rest of the loco, which I'll come to in a minute.  OTOH, if the motor runs at normal speed, you must look elsewhere. 

 

With the motor still out of it's mount, push the loco gently from one end or the other by hand.  Do the wheels turn freely or does the loco slide along the track?  If the latter, something is impeding free movement and overloading the motor.  Prime suspect, since you say the loco has spent some time out of use, will be the coloured lubricating grease in the gearbox; this stuff can solidify and become the opposite of a lubricant (a stifficant?).  I don't like the stuff anyway as it has a tendency to pick up crud even when it is working properly, and remove it with a rattlecan switch cleaner, getting rid of any residue with an old stiff toothbrush.  When the switch cleaner has evaporated, you can re-lube as sparingly as you can get away with with a non-mineral machine oil.

 

The other possibilities are gunge in the axle channels and wheel bearings, as a result of it being picked up in the grease, or overtightened keeper plate screws.  With the loco held upside down, take the keeper plate off, carefully because the motor/chip feed wires are attached to it, and clean the inside of it.  This is a good time to do any adjustment or cleaning necessary on the pickups.  Lift each wheelset out one by one to examine, and clean/oil if needed, the channel and the axle, taking care especially with the centre axle not to pull the connecting rod and piston out of the cylinders.  They can be replaced if you do pull one out, but it is a fiddly process with delicate parts, and best avoided if you can.  When you re-assemble, check for free running as you tighten the keeper plate screws.  This is a balancing act; too loose will affect the gear meshing and lead to increased gear wear, but too tight will have the keeper plate fouling on the axles and inhibiting movement.  Have a look at the motion as well to ensure that nothing is fouling, and that the slide bars are parallel to each other and the side of the loco, and the crosshead not binding on them. 

 

The loco should (famous last words) now be running smoothly, but before you put the body back on, check the insides of the splashers for gunk and fluff, something else that might be inhibiting free running.

 

It is possible that the motor is failing as Cypherman suggests.  The magnets lose strength over time and the motor becomes weak, the result being the sort of slow running you are experiencing.  Replacements are not life-changingly expensive, and you can have them remagnetised, though I've never done this.  You will be able to look at this once the body is removed; compare the magnetism of this loco with one that runs properly with a pin or something to see how firmly it sticks to the magnet.  Running with the top off will show up any overheating as well; perhaps the bearings have run dry.

[BMacdermott]

Hello Johnster

 

Many thanks for your comprehensive reply - I have tried most of what you say, but, sadly, to no avail.

 

The loco is DC but has a DCC harness (I think that's what they are called). DCC-ready.

 

The gearbox etc has been thoroughly flushed out with spay can switch cleaner (IPA).

 

The body was already off and nothing is binding (brake blocks, track pins stuck in the works, keeper plate adjusted or off).

 

When I put my Xuron track cutters near the motor, the pull was so strong it took me by surprise! In fact, I can lift the loco off the track with cutters firmly attached to the motor with no chance of it falling off!

 

I have tried a different controller and swapped the tender - no difference.

 

There is not even the faintest rise in temperature of the motor as it 'fails' nor is there any smell of burning.

 

As noted earlier, it is like someone has fitted a speed limiter and only permitted maximum distance running of about five feet before failing!

 

Brian

[cypherman]

Hi,

You say the gearbox was flushed out with switch cleaner. You did remember to re lubricate it again. other wise it is running dry. Also try looking at the pick ups. Are they in the right place or are they perhaps binding. Does it run better in one direction.

[The Johnster]

Does the chassis run freely when you push it with the motor not meshing to the gears?  This will indicate any problems with fouling or binding and, if it does run freely, means that the problem has to be in the motor or the gear meshing.  Does the motor run freely when it is out of it's cradle mounting?  If the chassis runs freely and the motor runs at normal speed when it is not under load, something is overloading the motor.  Check for any possibility of a short, as the symptoms you describe can be produced by a 'partial short', perhaps broken insulation or solder too close to something else conductive on the DCC chip base circuit board.  Run the motor directly to the terminals and then from the feed wire side of the DCC base; this will isolate any problem in the base, which can be simply wired around and left out of use.  Have a look at the soldered connections between the pickup strips and the feed wires on the inside of the keeper plates as well; the solder can be pretty close here and gunge may be allowing some current through.  Another place where this may be happening is around the capacitor between the motor terminals.

 

Make a close inspection of the worm to gear meshing; it might be too tight, causing a drag on the motor, but I would expect the motor to heat up in this case, and my current view is that current is going where current should not go, but not to an extent that disables the loco completely immediately.

 

Another possibility, if you can isolate the problem to the motor, is that the copper wire windings are broken or the pole segments are fouling on the motor casing, or that a broken off lump of carbon brush has become partly jammed, causing a partial short between the motor and the casing.  You can check for fouling of this sort by spinning the motor by hand from the worm gear.  As this is a can motor, you will not be able to get inside to inspect for this, but you can isolate the problem by swapping the motor for a similar motor that you know runs properly from one of your other Granges or any similar motor.  If the loco works properly with the swapped motor, then you will have to replace it with a new one from Hornby in the loco you have pinched it from.

 

I suspect the problem, whatever it is, is not pickups; if these are not bearing correcly on the wheel tyre backs or are dirty the loco will run jerkily in fits and starts but at normal speed when it is moving, rather than the slow 5 foot death you describe.  Be Of Good Cheer, we will sort it out one way or another sooner or later somehow or other!  The worst that can happen (I hope!) is that you will have to spring for a new motor...

Edited May 24, 2021 by The Johnster

[Right Away]

In general a “DCC Ready” locomotive would have a direct-fit blanking plug inserted into the decoder socket, enabling DC running. Your mention of a harness suggests a wired decoder is fitted with DC running enabled in CV29. If this is the case, the decoder could be at fault.

 

Interestingly, my two Hornby Granges have the decoder socket in the tender but in both cases the information sheets show this to be in the locomotive itself. Not a very helpful diagram (suggesting that at some point the socket was fitted in the loco) although the presence of connecting wires and loco/tender plug said otherwise.

 

 

 

[BMacdermott]

9 hours ago, cypherman said:

Hi,

You say the gearbox was flushed out with switch cleaner. You did remember to re lubricate it again. other wise it is running dry. Also try looking at the pick ups. Are they in the right place or are they perhaps binding. Does it run better in one direction.

Hello cypherman

 

All suitably re-lubricated and all pick-ups exactly in the right place.

 

The loco was running with no problem when it was put away just a few weeks ago (probably less than 6 weeks) but had ''the problem' as soon as it was back on the layout.

 

She moves very smoothly in any direction.

 

Brian

[BMacdermott]

Hello Johnster

 

Thanks again.

 

I have gone as far as I can go with 'fault finding' and nothing is showing up. It is beyond me as to taking the motor out!

 

I have managed to get a bargain price replacement in the meantime. I have also rung Hornby, but R2404 is too old for them to keep parts. I guess the old one will go on eBay as a non-runner one day!

 

Brian

[The Johnster]

Taking the motor out is easy; you unclip it from it's plastic cradle mount by gently levering it upwards with a small screwdriver.  It press fits back in when you re-insert it.  It may be secured with a screw that you will have to remove.  This will enable you to test run the motor out of the chassis and fault trace to the motor or the chassis.  Don't scrap the old motor until you've done this; there is no point in replacing the motor should you be able to source a replacement only to find it is still affected by the same unresolved problem somewhere in the chassis.

[BMacdermott]

Ah! Ok Johnster, thanks, I'll try that.

 

Brian

[BMacdermott]

Hello again Johnster

 

Well...I was able to remove the motor far more easily than I had imagined! It is held by a small 'L' shape bracket and screw.

 

The chassis without motor pushes along superbly smoothly with no binding.

 

The motor itself - when connected with two wires from the track - responds immediately and runs up to what I guess would be full speed with no hesitation, heating, sparking etc.

 

Having put it all back to together, she still runs smoothly but will no go faster than dead slow and then fails after about 5ft.

 

There is a 'small round thing' in the wiring - a capacitor? Could that be the problem? Can it 'blow'?

 

Brian

[JeffP]

Does the motor have brushes?

If so, are they free to move, snd not clogged with fluff etc?

Are they still a decent length?

 

I once had a washing machine which would turn slowly and wash, but refuse to spin if the brushes were worn.

[The Johnster]

It probably can, but I can’t visualise the circumstances in which a high enough current to damage it would occur.  But we are making progress!  We now know that the motor is not defective and that the chassis is not binding or fouling anywhere; the net is closing in on the fault.  I reckon this to be a partial short of some sort, but I may well be wrong!  If it was a running problem or gear meshing issue I’d expect the loco to run poorly and jerkily but continuously, not the 5’ slow death. 

 

We know that the motor is a good ‘un, so I’d suggest that the next step is a close examination of the path current takes between the pickups and the motor.  As you have two other Granges, swap out the keeper plate with the pickup strip from one of the others and install it on the problem loco (this involves de- and re-soldering the feed wires from the front of the strips).  If the loco now runs properly you have solved one problem and know exactly what the problem is on the loco you’ve swapped the keeper plate to.  Check that there is no oily gunge on the inside surface of the faulty keeper plate which might have the sort of low but not completely absent conductivity that would confirm my suspicions. 
 

If the swap makes no difference, the next possible problem will be located at the DCC chip holder.  Again, swap it with one from a working Grange; if the problem loco now runs properly and the other one doen’t, again, you’ve isolated the fault an know what to replace on the other loco.  
 

You can rewire so as to bypass the chip holder and the capacitor altogether; I revived an otherwise full short dead Baccy 56xx in this way once.  The cap’s purpose is to suppress tv or radio interference, but this is usually unnecessary on modern models with can motors. 
 

Sometimes mystery faults can be resolved simply by swapping components, in which case all will be well even if you don’t quite know why!

[The Johnster]

6 minutes ago, JeffP said:

Does the motor have brushes?

If so, are they free to move, snd not clogged with fluff etc?

Are they still a decent length?

 

I once had a washing machine which would turn slowly and wash, but refuse to spin if the brushes were worn.

It will be a sealed can motor, with brushes inside the casing, which prevents fluff and stuff from getting in there. You replace the motor as a complete unit when the brushes wear out. 

[BMacdermott]

12 minutes ago, JeffP said:

Does the motor have brushes?

If so, are they free to move, snd not clogged with fluff etc?

Are they still a decent length?

 

I once had a washing machine which would turn slowly and wash, but refuse to spin if the brushes were worn.

Thanks JeffP

 

Johnster beat me to the keyboard!

 

Brian

[BMacdermott]

Hello Johnster

 

Many thanks for your continued support!

 

I have stripped all the 'DCC stuff' out so that it is just plain wires - but exactly the same 5ft or so then dies. Give it a five second break, and it will do it all again!

 

I'm afraid the swapping and re-wiring on the keeper plates is a bit 'too worrying' for me and I don't want to wreck any of my good engines!

 

Brian

[The Johnster]

Ok, don't do anything you aren't comfortable with.  Have you deep-cleaned the top, inside, surface of the keeper plate?  I ask because lubricant from the axles their bearings has a tendency to find it's way into this area. 

 

The fact that the loco performs in exactly the same way each time, 5 feet slow running and then a stop, and is able to repeat that exact performance within a few seconds of the first time is mystifying.  Doing it once sounds like the sort of partial short with a small amount of current getting across from the positive to the negative side that I've been suspecting, but it would do so once and be incapable of movement until the controller's overload protection resets.  I have to admit that I cannot recreate in my mind a set of  circumstances that would account for this.  I'll admit to being stumped, and if we cannot swap components, I can't see how to continue with fault finding. 

 

I was hoping to be able to find a solution to this but clearly cannot; I'm stumped.  My best suggestion now, a bit of a cop out, is to contact Hornby for advice, and to return the loco to them for repair if that is what they suggest.  We have made progress of a sort, though; we now know that the motor is capable of running properly and that the chassis runs freely and correctly, which we didn't on Sunday!  My apologies for not being able to provide a happy ending to the story. 

 

 

[cypherman]

Hi all,

Is there a possibility that there may be a dry solder joint some where. When it gets warm the joint opens up. Then the engine stops until the joint cools down and reconnects.

[BMacdermott]

Hello cypherman

 

One of the 'mystifying problems' is that the loco was fine before it was put away for some weeks.

 

Hello Johnster

 

All areas of the loco have been thoroughly cleaned. I phoned Hornby about the loco, but it is too old for them to touch. Although the loco 'stalls', my controller stays fully alive. As noted earlier, I have changed controller with no effect.

 

Brian

[cypherman]

Hi,

Well if you have tried everything else, I suppose the next option is to either sell it or get a new motor and see what happens. See if you can buy a cheap Chinese motor for it rather than a new Hornby one.

[ikcdab]

These things must have a reason somewhere. I might try swapping the motor with one of the locos that runs fine and see what happens...

[BMacdermott]

Thanks Ian

 

Not being overly 'mechanically or electrically gifted', I'm loathe to risk wrecking any of my good ones.

 

Brian

[The Johnster]

1 hour ago, cypherman said:

Hi,

Well if you have tried everything else, I suppose the next option is to either sell it or get a new motor and see what happens. See if you can buy a cheap Chinese motor for it rather than a new Hornby one.

He’s proven that the motor works fine when it is out of the chassis, so a new one is not needed and won’t make any difference.  Ot is a mystery fault, sure enough, but has to be with the wiring or the rolling chassis.  I thought it might be a short, but the controllers are unaffected.