Hornby 8f Tender short

[down the sdjr]

Hello everybody, I am looking for advice again. I recently bought a Hornby 8F loco drive that seems to have a short in the tender, the loco works fine without the tender attached. I have tried to insulate the pin witch seems to help a bit, does anyone have experiance of this? I am thinking of cutting the wires in the tender as a last resort.

Thanks

Paul.

[micklner]

Check that the Tender wiring hasnt been reversed. It has happended on Hornby A4's

[DCB]

We had this with the 9F, the tender chassis had Mazak rot and had swollen so the insulated wheels shorted against the chassis.  We crumbled the chassis into more or less dust, binned the wiring and fitted a Triang Hornby class 47 trailing bogie chassis which was a direct replacement.

On the Black 5 removing the tender pickups and wiring increased the haulage by 40% so unless you are using DCC ripping the lot out is an excellent idea.

We don't have a Hornby 8F, our H/D 8Fs are only 60 years old and are not due for replacement yet, they also haul 40 wagons where Hornby 28XX etc struggle with 20.

Edited September 14, 2019 by DavidCBroad

[down the sdjr]

2 minutes ago, DavidCBroad said:

We had this with the 9F, the tender chassis had Mazak rot and had swollen so the insulated wheels shorted against the chassis.  We crumbled the chassis into more or less dust and fitted a Triang Hornby class 47 trailing bogie chassis which was a direct replacement.

On the Black 5 removing the tender pickups and wiring increased the haulage by 40% so unless you are using DCC ripping the lot out is an excellent idea.

DC layout, so may rip out as you say, its odd though i cant work out where the short is, seems to happen on corners. 40% increase?

Thank you for your reply.

[GWR-fan]

If the loco has the two fine upper power pickups on the drawbar then slightly spread them further apart.  When the loco enters a curve the upper pickups contact the  opposite polarity centre pin on the tender frame resulting in a short.

[kevinlms]

8 hours ago, down the sdjr said:

DC layout, so may rip out as you say, its odd though i cant work out where the short is, seems to happen on corners. 40% increase?

Thank you for your reply.

I would spend the time investigating properly before ripping out the wiring. 

You'll be pleased with yourself once you've fixed it!

[down the sdjr]

4 hours ago, GWR-fan said:

If the loco has the two fine upper power pickups on the drawbar then slightly spread them further apart.  When the loco enters a curve the upper pickups contact the  opposite polarity centre pin on the tender frame resulting in a short.

 

39 minutes ago, kevinlms said:

I would spend the time investigating properly before ripping out the wiring. 

You'll be pleased with yourself once you've fixed it!

I will have a good try at everything before i take drastic action, thank you.

[kevinlms]

11 hours ago, DavidCBroad said:

so unless you are using DCC ripping the lot out is an excellent idea.

 

Sorry but I fail to see the relevance to DCC. If the pickups are 'faulty' in some way and causing problems, then surely you can either fix them in some way or dispose of them if you 'give up'.

 

To suggest that it's a DCC vs. DC issue, is plain nonsense.

[DCB]

18 minutes ago, kevinlms said:

Sorry but I fail to see the relevance to DCC. If the pickups are 'faulty' in some way and causing problems, then surely you can either fix them in some way or dispose of them if you 'give up'.

 

To suggest that it's a DCC vs. DC issue, is plain nonsense.

 

My experience with DC is that tender pickups are a waste of time/ damned nuisance.   However DCC experts always seem to advocate extra pickups so I hesitate to suggest deleting them on a DCC model.  However it comes down to personal preference and I prefer 40% better haulage as in my County for instance now pulls 5 coaches instead of 3 up a 1 in 36. This is some way short of the 12 coaches up a 1 in 38 the full size locos were capable of.

[down the sdjr]

2 hours ago, DavidCBroad said:

 

My experience with DC is that tender pickups are a waste of time/ damned nuisance.   However DCC experts always seem to advocate extra pickups so I hesitate to suggest deleting them on a DCC model.  However it comes down to personal preference and I prefer 40% better haulage as in my County for instance now pulls 5 coaches instead of 3 up a 1 in 36. This is some way short of the 12 coaches up a 1 in 38 the full size locos were capable of.

I have noticed today that the loco does run better up my inclines with the tender off, very interesting.

[kevinlms]

18 hours ago, down the sdjr said:

I have noticed today that the loco does run better up my inclines with the tender off, very interesting.

Usually the point of fitting pick ups to the tender etc, is to get more reliable power pick up, rather than just relying on the loco alone.

The old Tri-ang locos were notorious poor performers, even on their own points. Why, because they only picked up off 4 wheels, even large locos like a Pacific. Coupled with the longish plastic sections of 'rail' at the frogs, they were very prone to stalling. They were also lightweight and that is why they introduced 'Magnahesion', but of course it only works on steel track. I remember the disappointment, when I purchased my first Peco point & length of nickel-silver track!

 

However, additional pick ups if not set up well, will cause extra friction and thus reduce the haulage capacity. In your case, they are apparently causing a short, into the bargain.

Naturally, it's your choice how you choose to deal with the fault.

[5 C]

I had a loco drive Hornby Coronation which exhibited similar symptoms. It worked fine without the tender but was prone to shorting out when coupled to the tender, particularly on curves.

 

I eventually traced the fault to the fine black wire that runs from the loco drawbar to the motor and takes the feed from the tender. The routing of this wire over and through the trailing truck had caused the insulation to wear away and make occasional contact with the chassis. A small sliver of insulation tape and all was well. 

 

Obviously the 8F doesn't have a trailing bogie but on many Hornby tender models, those fine black wires are crammed into confined spaces which can easily lead to wear over a period of time. They're usually held in place by a small and not always effective piece of black tack. The worn insulation that I encountered was barely visible - the size of a pin head - but it was enough to bring everything to a halt.

[34theletterbetweenB&D]

On ‎15‎/‎09‎/‎2019 at 00:51, down the sdjr said:

... cant work out where the short is, seems to happen on corners...

So it is probably mechanical action with the tender coupled on that causes the short, and that means that the short location isn't mecessarily in  the tender, because the drawbar on the loco moves when the loco and tender are on a  curve, which is where you are seeing the trouble.

On ‎15‎/‎09‎/‎2019 at 06:03, GWR-fan said:

If the loco has the two fine upper power pickups on the drawbar then slightly spread them further apart.  When the loco enters a curve the upper pickups contact the  opposite polarity centre pin on the tender frame resulting in a short.

There's one potential location, notice that the correction required is not on the tender.

21 minutes ago, 5 C said:

I had a loco drive Hornby Coronation which exhibited similar symptoms. It worked fine without the tender but was prone to shorting out when coupled to the tender, particularly on curves.

 

I eventually traced the fault to the fine black wire that runs from the loco drawbar to the motor and takes the feed from the tender. The routing of this wire over and through the trailing truck had caused the insulation to wear away and make occasional contact with the chassis. A small sliver of insulation tape and all was well. 

And there's another location, damage to wire insulation on the loco.

 

And there is more:

 

Wire detached from the drawbar wipers, which can lead to a short when the free end contacts the loco block or the other set of wipers, 'actuated' by the movement of the drawbar as the loco moves onto the curve.

 

And also, unless Hornby have changed the mechanism construction, the chassis block is live to one rail and vulnerable to shorts on curves from the wheels on the other rails. What's that got to do with the tender you ask? The tender imposes a drag (see below) and pulls the rear of the loco over a little more on curves, which means the wheels position differently in the chassis block.

 

On ‎15‎/‎09‎/‎2019 at 12:52, DavidCBroad said:

My experience with DC is that tender pickups are a waste of time/ damned nuisance.   However DCC experts always seem to advocate extra pickups so I hesitate to suggest deleting them on a DCC model.  However it comes down to personal preference and I prefer 40% better haulage as in my County for instance now pulls 5 coaches instead of 3 up a 1 in 36...

 

21 hours ago, down the sdjr said:

I have noticed today that the loco does run better up my inclines with the tender off, very interesting.

It is my opinion that the materials Hornby use for the wipers doesn't work optimally with the tyre material, and can be very draggy indeed, and typically worsens with running. The use of a very crude inside bearing for the tender wheelsets doesn't help either. I had an 8F all but stopped by its tender from this combination of factors, not too surprising considering the poor traction it starts out with. (Hornby could so do with renewing this model to the standard they now achieve: to name two for comparison, the O1 2-8-0, and K1 2-6-0 both well outperform the 8F.)

 

[down the sdjr]

2 hours ago, 34theletterbetweenB&D said:

And also, unless Hornby have changed the mechanism construction, the chassis block is live to one rail and vulnerable to shorts on curves from the wheels on the other rails. What's that got to do with the tender you ask? The tender imposes a drag (see below) and pulls the rear of the loco over a little more on curves, which means the wheels position differently in the chassis block.

Very informative post, thank you.

What you describe about the extra drag makes a lot of sense as when i started running the loco in it seemed fine the problems started when i attached some coaches then it just got worse.

Currently i have put a piece of insulation tape on the pickup bar on the tender and its working better, not 100% though.

I do have a good Megger multimeter so i could check for the short or continuity but not sure how to do it.

Thanks for the replies everyone, much appriciated.

Paul.

[34theletterbetweenB&D]

2 minutes ago, down the sdjr said:

...I do have a good Megger multimeter so i could check for the short or continuity but not sure how to do it...

The problem is that you are looking for an intermittent fault that only occurs when the loco is in motion. My favourite trick is to operate the 'problem child' in near darkness, on those parts of the layout where the trouble is known to occur, and look for sparks. You have to be able to get low down and fairly close in, and be able to observe several passes both sides. Can be a little tedious, especially if the fault is very intermittent or can only be seen at just the right angle.

[down the sdjr]

3 hours ago, 34theletterbetweenB&D said:

The problem is that you are looking for an intermittent fault that only occurs when the loco is in motion. My favourite trick is to operate the 'problem child' in near darkness, on those parts of the layout where the trouble is known to occur, and look for sparks. You have to be able to get low down and fairly close in, and be able to observe several passes both sides. Can be a little tedious, especially if the fault is very intermittent or can only be seen at just the right angle.

Crikey, what have i let myself in for?

Its do or die time, i can either return the train to Hattons bought "S/H like new" or start cutting stuff out. Im temted to cut the tender stuff out to see if DavidCBroad solution works, if not it will have to sit in a siding.

I have notice the tender connection is the same as on the Hornby West country class and ive never had a problem with those.

 

[down the sdjr]

On 15/09/2019 at 06:03, GWR-fan said:

If the loco has the two fine upper power pickups on the drawbar then slightly spread them further apart.  When the loco enters a curve the upper pickups contact the  opposite polarity centre pin on the tender frame resulting in a short.

After my last post i stomped up into the loft with the hump. I bent out the 2 lower fine pins and the loco is running good now.

Lets see how it goes, thank you to everyone who has posted, i really appriciate your time, i must say i am losing faith with Hornby, my Bachmann 4fs leave them miles behind, but that may just me being annoyed.

[bike2steam]

Losing faith with Hornby - let me know if you wanna get rid of the 8F. I have 8, ok one runs on a Bachmann WD chassis, but the 7 others run well enough to haul 50 Bachmann minerals without a hint of a struggle, yeah Hornby ain't perfect. Mine are 'fine-tuned' for super smooth running, and I prefer tender pick-ups for just that - have fun.

[down the sdjr]

37 minutes ago, bike2steam said:

Losing faith with Hornby - let me know if you wanna get rid of the 8F. I have 8, ok one runs on a Bachmann WD chassis, but the 7 others run well enough to haul 50 Bachmann minerals without a hint of a struggle, yeah Hornby ain't perfect. Mine are 'fine-tuned' for super smooth running, and I prefer tender pick-ups for just that - have fun.

I grew up in Blandford, if the loco does not work for me you are welcome to have it free of charge being a Blandfordian.

[34theletterbetweenB&D]

1 hour ago, down the sdjr said:

...am losing faith with Hornby, my Bachmann 4fs leave them miles behind, but that may just me being annoyed.

Ah, but here's something you perhaps don't know. This model is one of relatively few steam locos remaining in Hornby's main range that contains Margate content. From the new loco drive Britannia of 2006 they fully hit their stride in China, and apart from a little wobble under the title design clever, their steam loco introductions since have been very satisfactory. (Some are very good verging on excellent, I'd cite the B12/3 as a real delight, looks very fine, near all metal body, very smooth drive and excellent traction.)

[down the sdjr]

3 minutes ago, 34theletterbetweenB&D said:

Ah, but here's something you perhaps don't know. This model is one of relatively few steam locos remaining in Hornby's main range that contains Margate content. From the new loco drive Britannia of 2006 they fully hit their stride in China, and apart from a little wobble under the title design clever, their steam loco introductions since have been very satisfactory. (Some are very good verging on excellent, I'd cite the B12/3 as a real delight, looks very fine, near all metal body, very smooth drive and excellent traction.)

Fair enough, i was a bit angry and perhaps pointing it in the wrong direction.

[GWR-fan]

Until recently Bachmann did not bother with tender power pickups.  Hornby persisted for a generation or more with a "live" drawbar, initially drawing on just one side of the polarity but around the turn of the century chose to pickup power on both rails from both the loco and the tender.  The live drawbar has its advantages and alas, it has the occasional disadvantage like shorted out connections and the fine wires breaking at the drawbar.  The drawbar connection is not ideal for DCC installations as pickup can be erratic and unreliable.  When it works like designed then it is fine but does require the occasional fine tuning for reliability.  Until the introduction of the potentially troublesome umbilical connection the dual power pickup drawbar was on just about all Hornby tender locomotives produced since around 2000.

[GWR-fan]

8 hours ago, 34theletterbetweenB&D said:

The problem is that you are looking for an intermittent fault that only occurs when the loco is in motion. My favourite trick is to operate the 'problem child' in near darkness, on those parts of the layout where the trouble is known to occur, and look for sparks. You have to be able to get low down and fairly close in, and be able to observe several passes both sides. Can be a little tedious, especially if the fault is very intermittent or can only be seen at just the right angle.

 

Reminds me of the days of old when troubleshooting expensive brass locomotives that would not run reliably.  The tolerances were usually so close that most moving parts on the frame shorted out.

[34theletterbetweenB&D]

10 hours ago, down the sdjr said:

Fair enough, I was a bit angry and perhaps pointing it in the wrong direction.

Then again, Hornby have arguably dragged their feet over renewing some of what should be 'core' locos in their range, and that's bound to cause some annoyance.  And then there is:

 

8 hours ago, GWR-fan said:

... Hornby persisted for a generation or more with a "live" drawbar, initially drawing on just one side of the polarity but around the turn of the century chose to pickup power on both rails from both the loco and the tender.  The live drawbar has its advantages and alas, it has the occasional disadvantage like shorted out connections and the fine wires breaking at the drawbar.  The drawbar connection is not ideal for DCC installations as pickup can be erratic and unreliable... 

And also using the chassis block as part of the pick up path. Both of these clearly obsolescent practise when DCC - with its intolerance of short circuits - was about to make a large impact in RTR OO. Happily Hornby did make the changes required on new introductions; but have been very slow to make revisions on their older designs.

 

Caught between a rock and a hard place I rather feel: needed the cash cow sales of the older models of popular subjects - such as the 8F and Black 5 - to fund the new introductions made to their much improved standard, first seen on the Britannia, and they have made further progress from there.

[down the sdjr]

 A quick update.

After bending out the drawbar contacts on the loco and i must admit i also cut out the feed wires in the tender, it is running really well.

What a powerful loco it is, hardly any speed difference from my inclines to the flat sections. I have added all the details (the brake pipes were missing so had to order those from Peters Spares), real coal, fire irons and crew.

I have learnt from this, i need to take time to understand how these models work and what can go wrong, after this past week i have a lot of respect for the manufacturers, these trains are a work of art, really well made and a bargain for the price really.

Thanks for all your advice, im sure i will have more questions soon.