Bachmann Jinty "vibrating "

[philsandy]

I have A Bachmann Jinty that is not running 100%.

When run on it's own it appears to run very well, however when it is coupled to a wagon the fault becomes apparent.

The wagon is constantly buffeting ever so slightly, ie. moving rapidly back and forth in the play between the 2 tension lock couplings (when either pulling or propelling).

If you place a finger ever so lightly on the loco it feels as if the body is very lightly vibrating.

 

Can anyone suggest what may be causing this.

I suspect the fault may be the motor. Is this motor used in any other Bachmann models? I might try and find a second hand one if I know what the motor type it is.

Edited August 4, 2017 by philsandy

[The Johnster]

Is the model new or have you had it a while, and if the latter has the problem developed recently?  If the model is new, return it to the dealer and swap if for one which runs properly, but if it has a few miles on it, then the problem is most likely to be dirt in the mechanism.  I doubt very much if it is the motor unless this is a very old model, but if it turns out to be that the part number is on the service sheet to quote for a replacement from Baccy.  I would go this route rather than trying to obtain one secondhand whose provenance and mileage will be uncertain.

 

It is probably doing it running on it's own as well but with no wagon coupled to be tugged about doesn't show it quite as much.  Bachmann locos are built with eyelets in the plastic 'keeper plate' that holds the wheels in underneath, and this may come in handy as I will explain.  Turn the model upside down, and attach wires from your controller to one of these eyelets (they are where the pickups are fixed to the plate) on each side.  Turning the knob should make the loco's wheels turn as current is supplied to the motor through the pickups.  Running them at a slow speed, check for wheels out of square or out of true, which will be easy to spot and even feel if you hold the loco steadily.  If they are out of square or true, then you have isolated the problem and it is quite serious and you need a new wheelset, but most likely they will be fine.

 

Next potential problem to eliminate is to check if the loco is clean and not gunged up.  Referring to the service sheet (in the box with the loco or downloadable from Baccy's website if you haven't got it), remove the keeper plate; this might need the couplings removing first.  Do not pull hard on this or try to move it away from the loco as the feed wires to the motor are soldered to it.  I put the small screws in a piece of blutac so that they don't make a break for the border.  The wheels, complete with axles, drive gear, and coupling rods, will lift out.  Examine them and the channels that they run in the chassis block, and give them a good cleaning if needed.  I use Maplins switch cleaner spray for this, it is powerful enough to blow most of any crud away altogether.  Wipe away the surplus spray with a bit of tissue wrapped around a modeller's screwdriver blade, amaze yourself with how black and gungy everything was, and very sparingly lubricate the axles where they bear against the chassis channels.  Give the motor worm, and the pickups where they bear on the backs of the wheels a good clean and clean the wheel tyres thoroughly. 

 

While the wheels are out, apply current to the pickups and check that the motor runs smoothly and evenly; it almost certainly will.  You will be able to hear from the noise it makes that it is running at a constant speed for whatever current you have applied, and without the gear being engaged it will run very slowly indeed.  Make sure the gear is cleaned with a bit of spray on an old toothbrush (for cleaning old teeth) and again, very lightly lubricate it.  I apply lube with a hypodermic syringe; these are available for the purpose from most general model shops as RC modellers use them as well.  Keep this separate from any other syringes that you or any member of your household may use for prescribed medical or any other purpose (mine lives in the modelling toolbox in it's own compartment)!

 

Now have a look at the pickups, which can cause the running problem you are having if they are not evenly applying pressure to the wheels.  You may need to adjust some or all of them by gently bending them inwards or outwards.  Put the wheels back carefully, and position the pickups behind them, then re-attach the keeper plate with the screws which you haven't lost because you used my tip of keeping them safe in a lump of blutak.  Your model should now run smoothly, and your 4mm scale guards will be grateful in their vans.  

 

If you haven't done this sort of thing before, don't worry.  The model is designed to come apart in this way which is why Baccy supply you with a service sheet; this will also give you the part numbers for replacing anything that cannot be repaired.  Take your time, be methodical, and ask someone here if you get stuck.  

Edited August 4, 2017 by The Johnster

[DCB]

Follow Johnsters instructions but also turn it upside down and just check that the coupling rods are not bent in slightly as this can easily be done through handling and derailments and  leads to lumpy running.   Bachmann are usually very smooth with their flywheels, however they do run rough on some PWM controllers and on half wave on resistance controllers, so if the vibes are quite rapid and occur at very low shunting speed it could be a controller problem.

[34theletterbetweenB&D]

The problem description is typically a symptom of 'cogging', and the immediate question I would propose is much as 'Johnster' began: has it always done this, or is this a change from how it once performed? If the latter, has anything else been altered, especially relating to control of the model (change of controller, changes to layout wiring, converted to DCC, change of decoder, is it the same forward and reverse)?

 

Supplementary questions:

Are other locos of similar design showing this effect or not, when operated similarly?

Have you tried operation of the loco on track with supply from a battery?

 

 There's no complaints relating to noise or any other defect in operation, so I wouldn't leap directly to the motor as the cause of the problem at this stage. (Last time I was shown a mechanism apparently with this problem it was induced by the control system, which had some sort of problem in power regulation stability. The loco ran perfectly smoothly on battery supply, always a good check whether the problem is on the loco alone or by interaction with another system,)

... Is this motor used in any other Bachmann models? I might try and find a second hand one if I know what the motor type it is.

 Same motor in the 57xx, should replacement prove necessary. It may well be found in other small Bach steamers of course.

[The Johnster]

The points raised about controllers are good ones, and can be tested by connecting to a battery supply, which is pure dc.  If this cures the problem, that is a pretty good indication that the motor doesn't like the current it is being fed.

 

I believe the Baccy 64xx, 57xx and Johnson 1F use the same motor, but the mounting plates are different.  It is certainly the same overall design, though may differ in details.  The GW locos have a different wheel spacing and some parts will be different, as well as the coupling rods being a different shape.

 

I should have mentioned the possibility of connecting rods having become bent; if this is the case it will be visible as you look along their length.  If they are too far gone to be straightened with a minor application of brute force and ignorance, they will have to be replaced, in which case it will be worth investing in a set of nut spinners or runners to take the crankpins out.  These need to be kept in the lump of blutac until they are needed again.

Edited August 5, 2017 by The Johnster

[philsandy]

Many thanks for all your replies.

I'm sure I now know what the problem is.

I ran the loco at very slow speed propelling a wagon... but with the body removed, and Hey Presto! it runs perfectly, the two tension lock draw bars in constant contact with each other, no oscillating.

 

There is 1mm clearance between the diameter of the motor body and the internal of the loco body, but a couple of the capacitors may have been tight up against the inside of the loco body, so I bent these slightly so they would clear, and there was a big improvement when running with the body back on, not as perfect as when the body is off, but nowhere near as bad as it was.

I'm now suspecting there is not enough clearance between the top of the motor body and the underside of the boiler, and it's this that is still causing the slight vibration in the loco body.

[dhjgreen]

Many thanks for all your replies.I'm sure I now know what the problem is.I ran the loco at very slow speed propelling a wagon... but with the body removed, and Hey Presto! it runs perfectly, the two tension lock draw bars in constant contact with each other, no oscillating.There is 1mm clearance between the diameter of the motor body and the internal of the loco body, but a couple of the capacitors may have been tight up against the inside of the loco body, so I bent these slightly so they would clear, and there was a big improvement when running with the body back on, not as perfect as when the body is off, but nowhere near as bad as it was.I'm now suspecting there is not enough clearance between the top of the motor body and the underside of the boiler, and it's this that is still causing the slight vibration in the loco body.

Hmmm, mine sounds like a bag of nails, I will give that a try.

[liathach]

Just looked up this post.  I've been running a couple of Bachmann Jinties for years.  They display the same behaviour in that wagons tend to "vibrate" rapidly, especially when being propelled and in the low to medium speed range.   I'm on DCC (Zimo decoders).  I've swapped around motors and tested different decoders and all sorts of alterations to motor-related CVs.  Nothing seems to solve the odd issue. The much heavier Pannier chassis (with the same motor) doesn't yield the same vibration when in motion.

 

Out of interest, does anyone have the 1F loco (think this has the same motor?) or the Coal Tank (newer design so might be an updated motor) for comparison?

 

From the Bachmann website, it looks like the more recent Bachmann releases of the Jinty have an updated chassis.

[liathach]

On 06/12/2021 at 13:39, liathach said:

Just looked up this post.  I've been running a couple of Bachmann Jinties for years.  They display the same behaviour in that wagons tend to "vibrate" rapidly, especially when being propelled and in the low to medium speed range.   I'm on DCC (Zimo decoders).  I've swapped around motors and tested different decoders and all sorts of alterations to motor-related CVs.  Nothing seems to solve the odd issue. The much heavier Pannier chassis (with the same motor) doesn't yield the same vibration when in motion.

 

Out of interest, does anyone have the 1F loco (think this has the same motor?) or the Coal Tank (newer design so might be an updated motor) for comparison?

 

From the Bachmann website, it looks like the more recent Bachmann releases of the Jinty have an updated chassis.

 

 

I've just tested a few more Bachmann engines:

 

Two Bachmann 57xx Panniers (same motor) produce the same vibration effect, albeit not as noticeable in intensity.  The range of speeds when the vibration occurs is less than the Jinties (I believe this is probably affected by the extra weight of the Panniers?).

 

More modern design Southern E4 tank: dead smooth no visible vibration on same wagons and no audible vibration.

 

 

[The Johnster]

None of my 5 Baccy panniers produce such an effect, though one doesn’t count as it’s a 94xx with a coreless motor.  I’m on DC, and all of my Bachmanns run smoothly, with one 8750 making a little buzzy noise.  I suspect that this vibration issue is a feature of DCC, and I can’t help you with it because I know very little about DCC.  But I’m fairly sure it’s not the mechanisms. 

[Free At Last]

Having motors like this won't help... 

 

[The Johnster]

Looks like it's having what Jeremy Clarkson describes as a 'crisis', usually in respect of very happy ladies...

 

Needs lashing down (whatever you do, don't google that, especially in the context of the last sentence, unless you are fully prepared for the consequences and all children or other sensitive souls are out of view of the monitor), probably by tightening the restraining or mounting screw (oh 'eck, look, I'm not doing it deliberately, honest, but once you start it just goes on...) or, if all else fails, taping it to the chassis block.

[liathach]

I've had time earlier to try alternative motors in one of the panniers.  I managed to get a coreless motor to mesh with the gears.  Next job was finding the magic CVs to get the coreless motor smooth.  The previous vibrating NEM coupling issue has gone, so IMHO the small Bachmann motor creates the vibration.  I will test the coreless motor when I have more time.  If the coreless motor works well over time, I will change over the other Bachmann Jinties and Panniers to the same motor.

 

[liathach]

I've been closely monitoring other locos lately. 

 

I have a couple of Bachmann 56xxs.  They have a larger standard Bachmann 3 pole motor with a large diameter worm.  Both those cause wagon coupling vibration. 

 

45xx I also have a couple.  They have the larger Bachmann 3 pole motor.  These also cause coupling vibration, but not anywhere as noticeable as the 56xxs, 57xxs/8750s or the Jinties.  

I have run a number of different Hornby steam loco classes recently.  None of the Hornby locos impart the vibration on the wagons.  None of the diesels from Bachmann or Heljan run with the vibration.

 

Further to one of the earlier posts, I fixed one of the Jinty motors firmly to the cradle, but this had no effect on the vibration.  IMHO, the issue is with the Bachmann motor design.