Hornby 5MT derailments

[Guest Jack Benson]

Hi,

Almost all our tiny collection of SDJR locos are naturally from Bachmann, two exceptions, the latest loco driven Hornby 2P and Hornby 5MT, the former is a consistently good performer whilst t'other is not.

Despite resetting the bogie wheel's B2B with a DOGA gauge (it arrived with a 12,5mm B2B) the bogie derails at various turnouts (none of the other locos display the same habit)  

Before we waste effort on this model with a Brassmasters upgrade we need to solve the derailing issue.

 

Thank you  and cheers

 

Jack

 

 

 

 

 

 

[34theletterbetweenB&D]

This will be the usual patient plod through the possibilities.

 

Uncouple the tender temporarily and operate through the derailment  locations  (dragging the tender by the wiring link unless you can make up a blanking plug).

Remember b2b is a substitute measurement, anything non standard about the bogie wheel tyre and flange profiles?

With the bogie off the loco will it go through all the identified derailment locations trouble free?

On the loco is the bogie free to rise and fall relative to rail top, pivot and swing laterally?

 

[Guest Jack Benson]

Hi,

 

Standard Hornby product, no upgrades, just the B2B adjusted.

 

The loco sans bogie (and tender)  works perfectly whilst the bogie, when removed from the loco, can be pushed* through all the turnouts without problem. Therefore the issue might be the relationship between loco and bogie.  All the Bachmann locos and 2P (Hornby nee Mainline) have centre bogie pivots with a soft spring whilst the Hornby 5MT flops about on the end of a long rigid arm, presumably to cope with toy-like curves but very old-fashioned.

 

*The trusty Bachmann Jinty pushing like crazy.

 

Does any of the above help? Maybe Comet bogie with compensation or a sprung arm might help?

 

Cheers

 

Jack

 

 

[dhjgreen]

The Bachmann standard 4mt 2-6-4 is the same on the 2 wheeled bogie, I made a spring out of phosphor bronze strip.

[Rowsley17D]

I put a small piece of foam on top of the bogie so that some of the weight of the loco acts on it. Painted it black and it's not noticeable. My Black 5 used to waddle at the front end and it stopped this too.

[34theletterbetweenB&D]

54 minutes ago, Jack Benson said:

...the bogie, when removed from the loco, can be pushed* through all the turnouts without problem...

 

*The trusty Bachmann Jinty pushing like crazy....

Reading that it suggests the bogie is not free rolling. If true that needs to be fixed.

 

The old fashioned 'floppy arm' mount for the bogie is a limitation. With the bogie on the loco it should be possible to lift the front driving wheel slightly off the rail without the bogie coming off the track. A light spring of some sort set in the bogie rivet to act on the loco underside, is a good plan, as 'Rowsley 17D' suggests.

[Guest Jack Benson]

34C,

 

The bogie runs very freely, unfortunately, the design of the layout with hidden sidings precludes a simple shove with a finger, instead another loco just pushing the bogie, is employed. 

 

Cheers

 

Jack

 

 

[The Johnster]

When you say 'derails at various turnouts', does this mean that there are specific places at which the bogie derails?  Once you have ensured that the B2Bs are correct and that the wheels run true and square to the axle, and that they run freely, and that the bogie is free to move adequately in the lateral and vertical planes, the next thing is to look closely at the track if there are specific positions causing trouble.  It is particularly vital with pointwork that the turnout is smooth and level to the adjoining piece, and that there is no change in level at the 'vee'; this is even more important if the turnout is anywhere near a baseboard join or change in gradient.  It is possible that the baseboards and track were laid perfectly but have shifted position since. 

 

Sorry if this is teaching granny about sucking eggs, but if you've done everything you can to the loco and some of the above posts' suggestions have not helped, then process of elimination means that we must move from the loco to the track.  

 

Do the derailments happen on facing or trailing turnouts (bet it's facing, and at the vee!)?  Do the occur with the loco running tender first?  Are changes of gradient involved?  Check that the flangeways are free of debris which might be bothering Hornby wheels but not Bachmanns.

 

Another suggestion is to fix a small ballast weight to the top of the bogie if it can be done without compromising clearances; this may hold it down a bit better.

[Guest Jack Benson]

Hi,

 

Thanks, took in all the advice, re-checked the B2Bs on the Hornby bogie wheels with the DOGA gauge, removed the bogie from the loco (again) and applied a very slight downward bend in the long pivot arm, just enough to ensure that the bogie wheels remain in contact with the rails as the leading drivers lift. The result is  better progress through the hidden sidings but still no cigar, at least the tweak indicates the nature of the issue.

 

Thank you

Jack

[RonnieS]

Try a temporary weight on top of the bogie. I cut back my black 5 bogies and add weight.S

here

Hornby black 5 front bogie - Modelling Questions, Help and Tips ...

 

Edited May 11, 2019 by RonnieS
clarity

[Flying Pig]

13 hours ago, 34theletterbetweenB&D said:

The old fashioned 'floppy arm' mount for the bogie is a limitation

 

Assuming it is floppy.

 

7 hours ago, Jack Benson said:

applied a very slight downward bend in the long pivot arm, just enough to ensure that the bogie wheels remain contact with the rails as the leading drivers lift

 

This suggests it may not be.  The pivots must both be loose enough for the bogie to find its own level on the track independently of the rest of the chassis.  If for example the rivet holding the arm to the bogie is too tight, this can't happen.

[Il Grifone]

Are these the latest fine wheels or the old coarse Hornby wheels? If the latter the B2B needs to be a bit tighter (14.2mm or 14.7mm for DOGA). Check the bogie is able to follow ant track irregularities and that it passes freely though the flangeways.

 

Edited May 13, 2019 by Il Grifone

[Pete the Elaner]

What track & gauge are you using?

I assumed a DOGA finescale gauge (14.8mm) would be correct for code 75 track, but this seems to be wrong.

Their universal gauge seems to give better running.

 

I noticed with my Black 5 that the inside wheel lifts on a curve. A little more downward force on the bogie (extra weight may be the easiest) may help.

[Jim49]

If none of the above suggestions work, can I suggest that you swap the bogies between engines to see what effect that has. I see 3 outcomes;-

 

1) If both engines run through points without any problem then you are sorted. There's no logical explanation for this, just accept it and be happy.

 

2) If the original loco with the new bogie now runs through points and the other doesn't then the problem seems to be with the original bogie, wheels or swiveling arm. Concentrate on these parts. there will be something too tight, too wide or bent slightly causing the problem. it's just a matter of looking closely and comparing with the other bogie.

 

3) If both engines now have difficulty negotiating pointwork, it's nothing to do with me Guv'nor. Just put them back the way they were.

 

Jim

[Il Grifone]

7 hours ago, Il Grifone said:

Are these the latest fine wheels or the old coarse Hornby wheels? If the latter the B2B needs to be a bit tighter (14.2mm or 14.7mm for DOGA). Check the bogie is able to follow ant track irregularities and that it passes freely though the flangeways.

 

EDIT 

 

The DOGA intermediate gauge should be OK for these wheels, the finer standards may need slight easement. The problem with any B2B gauge is that they rely on the flange thickness being constant, but it varies between makes. Hornby wheels tend to have 0.5mm thick flanges and Bachmann prefer a thicker (0.7/8mm) flange. The critical dimension with wheelsets is the check gauge (B2B + flange thickness)'

 

I would try running the bogie through the pointwork by itself to eliminate any problem with its mounting. Some weight or downwards spring pressure might be beneficial. It is even possible the guard irons are catching on the pointwork.

[Guest Jack Benson]

Hello,

 

Just to thank everyone who contributed, the Black Five has settled into its role on Child Okeford as a smooth running, reliable loco. Hopefully it will emerge from the workbench after a mild facelift with  Brassmasters bits (though not the full monty) and an application of appropriate weathering.

 

 

Thanks once again to the members of RMweb, very much appreciated.

 

Cheers

 

Jack.

[34theletterbetweenB&D]

5 hours ago, Jack Benson said:

Just to thank everyone who contributed, the Black Five has settled into its role on Child Okeford as a smooth running, reliable loco...

Good. So following this:

On ‎11‎/‎05‎/‎2019 at 17:52, Jack Benson said:

Thanks, took in all the advice, re-checked the B2Bs on the Hornby bogie wheels with the DOGA gauge, removed the bogie from the loco (again) and applied a very slight downward bend in the long pivot arm, just enough to ensure that the bogie wheels remain in contact with the rails as the leading drivers lift. The result is  better progress through the hidden sidings but still no cigar, at least the tweak indicates the nature of the issue.

What further changes finally resolved the problem? (Good to have for other owners to consult.)

[Guest Jack Benson]

1 hour ago, 34theletterbetweenB&D said:

Good. So following this:

What further changes finally resolved the problem? (Good to have for other owners to consult.)

 

Turning the speed down on the controller to a prototypical level was the most effective pragmatic solution.

 

However the Hornby mechanism remains a source of frustration as the loco simply locked solid after trundling around, this morning,  whilst a visitor was watching (schadenfreude)

 

Cheers

 

Jack

 

 

[Rowsley17D]

If you have not had the Black 5 for long I'd be sending it back.

[Ben Alder]

Has the valve gear jammed? This can happen if you pick it up and happen to squeeze the gear. current Hornby outside gubbins are very fragile compared to the Margate stuff and steam locos with outside gear has to be handled very carefully.

[Guest Jack Benson]

11 hours ago, Ben Alder said:

Has the valve gear jammed? This can happen if you pick it up and happen to squeeze the gear. current Hornby outside gubbins are very fragile compared to the Margate stuff and steam locos with outside gear has to be handled very carefully.

 

The original comment should have been - "the loco simply locked solid whilst trundling around"  it was running through the hidden sidings (naturally) when it simply stopped. A gentle easing of the wheels to and fro' unlocked whatever was causing the issue to free, but had been no manual handling prior to the incident and the loco was running perfectly around the layout. Very odd but as this is being written the loco is, again, trundling around at a prototypical speed and without issue.

 

The episode does not frustrate, it merely defines the character of the loco.

 

Cheers

 

Jack

[34theletterbetweenB&D]

5 minutes ago, Jack Benson said:

... "the loco simply locked solid whilst trundling around"  it was running through the hidden sidings (naturally) when it simply stopped. A gentle easing of the wheels to and fro' unlocked whatever was causing the issue to free, but had been no manual handling prior to the incident and the loco was running perfectly around the layout. Very odd but as this is being written the loco is, again, trundling around at a prototypical speed and without issue...

One of the outside rods snagged, is the most likely cause given this description. Top suspect - and especially if your hidden sidings have smaller radius curves than elsewhere on the layout - is one of the connecting rods snagging on the leading crankpin.

 

Inspecting the loco from the underside, shift the driven wheelsets from side to side to see if any rods can foul and snag on other moving parts or fixed structure. I quite often either limit the sideplay of the leading driver of a six coupled loco and/or put a slight outward bend in the connecting rods to ensure there is no possibility of a connecting rod snagging on a leading crankpin.

[S&DWatty]

Ive added small weights to Hornby 5MT, Black 5 and battle of Britain models.   On Bachmann 4MT (2-6-4) the leading bogie needed the spring bent to slightly increase the downward force and some weight on it.

 

My track was pretty level when build but has setlled in places and you can see the "undulations".  It's an on-going trackwork job to maintian it.  Just like the real thing, eh? 

 

I agree with the comments above though, facing points are nearly always more problematic, making sure the entrance into and vee is level, free of debris and clean also helps a lot.

 

cheers

 

dave

[Guest Jack Benson]

Hello,

 

Having spent just under 45mins trundling around without further catastrophe, the loco is about to be 'upgraded' with a set of Gibson bevel rim wheels and the partial contents* of the Brassmaster's upgrade kit.

 

Apart from the fun of the upgrade, the proof of the pudding, will be whether it is a Dr Jekyll or Mr Hyde, after the process?

 

Cheers

 

John

 

*Just parts of the etch, buffers and draincocks.

[Rowsley17D]

Do let us know the outcome of the upgrade and a photo, please. My Black 5 needs a cosmetic upgrade too.