Powered Tenders

[brian usa]

Powered Tender Design

 

I decided to take that small heavy tender that came with my Roco steamer apart today, and have a look at how they designed theirs. I hope that some of the readers here realize that this small size tender was likely a bigger challenge than ones that might be designed for larger tenders on larger steam engines. Here are 2 of those small tenders (3 inches long) supplied with the Roco steamers

 

 

Before I removed the shell off the chassis, I wanted to do a little pushing test on a piece of 18”radius track to insure myself that it would go thru this tight curve, just as its boiler portion has done.

 

Basically it has sideways shifting axles that shift enough to allow the short wheel-base tender to negotiate the tight curve.

 

 

Notice that the 2 trucks DO NOT swivel. The shifting axles are enough to allow the tender to negotiate the tight curves,.... (simplicity and a savings of interior space).

 

Lets see whats inside,..

 

That's a cast metal portion of the tenders body that adds a lot of weight very efficiently right over those driving wheels. BTW, in this case we have both traction tire drivers and plain metal drive wheels,..that's because this tender is designed to run on DC and DCC.

 

If it were a dcc engine only it could be equipped with all traction wheels, as there would be no need to have power pick up in the tender that is getting its motor power from the decoder in the boiler portion. Here are the electrical pick-up strips for DC power to the tenders motor

 

 

This is a very neat way to cut down on more elaborate gear towers !!,..

 

And this same concept (non-rotating trucks) could be adapted to slightly longer such tenders, (similar to our current in-line/non-rotating rigid frame mounted driver wheels).

 

Couple of other items;
1) truck frames are just decorative push-ons that could be different for different engines

 

2) the top portion of the tender shell is detailed plastic glued onto the cast metal portion

 

 

Creative, intelligent design from Roco.

Brian

 

New contributor would like to hear of positives and negatives of this design??

[Miss Prism]

What's your estimate of the gear ratio?

 

[proton]

Could you measure the wheelbase please (mm)?  It would be nice to put that behind an LNER pacific to augment the adhesion.

John

[34theletterbetweenB&D]

1 hour ago, brian usa said:

New contributor would like to hear of positives and negatives of this design??

Typical of current good quality European design HO for adequate traction, allowing the owner to have it pull long trains on very small radius curves.

 

Is the loco powered? If not there's no possibility of the wheelslip that so regularly accompanied starting under load.

[GrumpyPenguin]

The model depicted is an older Roco design - the later ones are DCC ready (socket in tender), smaller motor with flywheel & a carden shaft (small diameter & hardly noticable) to drive the locomotive driving wheels.

Although this particular model does not have kinetic coupling between the locomotive & tender visually it is far superior to what UK manufactures expect modellers to accept - they would do well to take note.

I have a number of Roco Locomtives with this design (converted to DCC) & they are superb peformers in every respect. The traction tyres give no issues either.

[Michael Hodgson]

9 hours ago, 34theletterbetweenB&D said:

Typical of current good quality European design HO for adequate traction, allowing the owner to have it pull long trains on very small radius curves.

 

Is the loco powered? If not there's no possibility of the wheelslip that so regularly accompanied starting under load.

So are you advocating the modelling of wheelslip? 

 

Presumably could be achieved by intentionally mismatching the speed of a powered loco to the speed of a powered tender under DCC.

Is there a way of dynamically adjusting the characteristics of separate mechanisms in a consist, so that they run in sync at speed but not on starting?

[DCB]

4 hours ago, Michael Hodgson said:

So are you advocating the modelling of wheelslip? 

 

Presumably could be achieved by intentionally mismatching the speed of a powered loco to the speed of a powered tender under DCC.

Is there a way of dynamically adjusting the characteristics of separate mechanisms in a consist, so that they run in sync at speed but not on starting?

There is something about a loco drive  steamer easing away with just a hint of a slip , or judging how much wellie you can give it without excess slipping  which the clunky Railway DCC does not fit well with.  Its not a DCC issue, Scalextric  DCC hand throttles are great, but no one seems to make a decent real time speed control for railways.
I keep planning something I call "Protoslip" for a Bullied where the drive is shared between a heavy tender and a light loco powered from the sae motor with a differential so it the drivers slip the tender loses power.  
The gulf berween whats possible with DCC and what the trade churns out is well sad.
The Tender drive shown has traction tyres.   I banned them because they make the tracks so filthy

[Michael Hodgson]

6 hours ago, DCB said:

I keep planning something I call "Protoslip" for a Bullied where the drive is shared between a heavy tender and a light loco powered from the sae motor with a differential so it the drivers slip the tender loses power.  
The gulf berween whats possible with DCC and what the trade churns out is well sad.
The Tender drive shown has traction tyres.   I banned them because they make the tracks so filthy

That's a very interesting approach to effectively double heading with an engine and powered tender, I've not heard of anybody doing that before.  I wonder whether you have lower maximum tractive effort with a differential than without though.

 

Modern diesels have good hauling power and adhesion because they've got all or most of the weight on driving wheels whereas steamers often don't.  That results in some RTR lacking the hauling capability (especially on gradients) that I'd like them to have.  Our gradients are of course often unprototypically steep because of space constraints.  Getting as much weight as possible onto the drivers is the obvious answer, but may not be enough.  So double heading is the next answer to the problem.  Banking is another, although it can have problems if speeds aren't matched well enough, especially if there are issues about coupling/buffers.

 

I've always worked on the principle that both units should run at the same speed, or at least very similar.  I'm with you on traction tyes; they may help adhesion but not very much in my experience, and they certainly aren't worth the downside of dirt.  On the subject of dirt, one option for track cleaning however is coupled locos deliberately running at different speeds, so that one slipping polishes the rails as the other drags it slowly along (like some of these cleaning wagons).  DCC makes this possible, whereas it was difficult under DC.   I have experienced it as quite effective on old 3-rail DC in O gauge though - three identical 0-6-0s coupled, two chimney first the other tender first.  The two going forwards are suffficent to drag the other protesting with vigorous wheel spin does help clean the rails.  The extra weight of O gauge seems to make this method more effectively than it does in OO.

 

 

[DCB]

My first train was Hornby Dublo 3 rail and I had two Duchesses and an  0-6-2 tank    The tank would just haul all my 17 (?)  wagons around my not exactly level layout at a crawl but stopped dead if it slipped,  very realistic.   The opposite to most RTR where a burst of wheel slip  gets a stalled train underway again.
What I want from DCC is a capability for me to drive the train engine and my son drive the banker independently, rather than to consist them.  I  am pretty sure we could do it with Scalextric  DCC Hand throttles  but I'm not aware of any  Model railway DCC  equipment  giving that sort of immediacy of response.

[GrumpyPenguin]

European HO has a different approach - helix's are common & traction is very important, hence why many locomotives have traction tyres.

 

There are a few HO locomotives in my fleet that do have traction tyres but I simply do not suffer from "crud".

Crud will only spread if it's on the rail tops top start with - maybe, this (dare I say it) is the result of lazy &/or bad housekeeping ?

I have a couple of Roco/Piko "Track-Cleaning" wagons perminatly running with the springs removed so that it's just the weight of the cleaning pads on the rail tops. I also use some of thge Gaugemaster axel-hung pads.

Or another thing to consider is that maybe the Europeans use a better quality material for their tyres ?

[jjb1970]

Traction tyres seem to be a very Europe other than Britain thing. None of my North American or Asian models have traction tyres and hauling capacity is fine. I saw a beautiful professionally built Weinert kettle for sale the other day and it seemed odd to see traction tyres on such a model.

[34theletterbetweenB&D]

13 hours ago, Michael Hodgson said:

So are you advocating the modelling of wheelslip? 

Since it happened regularly with steam traction, I like to see it.

 

No complex solution is required since RTR OO abandoned both tender drives and traction tyres, which for a start ensures no chance of the 'mighty tender' moving before the loco does! With the loco driven wheels powered, a sufficiently heavy load will occasion a half turn or two of wheelslip on starting every now and again, which looks very well.

 

Assisting this effect are the close coupling systems now fitted to many RTR OO carriages; when optimally adjusted the whole train moves as a single piece. That means the loco has to start the entire trainload from rest, rather than pick up one carriage at a time. 

[kevinlms]

2 hours ago, DCB said:

What I want from DCC is a capability for me to drive the train engine and my son drive the banker independently, rather than to consist them.

I don't see why ANY DCC system can't do that. Use one controller to operate the train loco and a 2nd controller to operate the banker - DO NOT consist them.

 

As always, your statements suggest that basic DCC functions are harder than they really are.

[Michael Hodgson]

20 minutes ago, 34theletterbetweenB&D said:

Since it happened regularly with steam traction, I like to see it.

 

No complex solution is required since RTR OO abandoned both tender drives and traction tyres, which for a start ensures no chance of the 'mighty tender' moving before the loco does! With the loco driven wheels powered, a sufficiently heavy load will occasion a half turn or two of wheelslip on starting every now and again, which looks very well.

 

Assisting this effect are the close coupling systems now fitted to many RTR OO carriages; when optimally adjusted the whole train moves as a single piece. That means the loco has to start the entire trainload from rest, rather than pick up one carriage at a time. 

 

Traction tyres may have gone out of fashion for the latest locos, but a lot of us still run locos that have been around for a while, either because we too have been around for a bit longer or because our budget doesn't stretch to more than second hand.

 

Given a sufficiently heavy load, the train won't move at all.  A main line express steam engine looks silly if we can't trust it to pull more than a three coach train.  Some RTR locos are a lot worse than others.  That's why we may need to double head or bank heavy trains.

 

Well, passenger trains may start as a single piece, but that doesn't apply to traditional British loose-coupled goods trains, which do pick up one wagon at a time, and also come clanking one at at a time to a halt, depending of course on what the Guard was or wasn't doing with his brake.

[John Tomlinson]

3 hours ago, GrumpyPenguin said:

European HO has a different approach - helix's are common & traction is very important, hence why many locomotives have traction tyres.

 

There are a few HO locomotives in my fleet that do have traction tyres but I simply do not suffer from "crud".

Crud will only spread if it's on the rail tops top start with - maybe, this (dare I say it) is the result of lazy &/or bad housekeeping ?

I have a couple of Roco/Piko "Track-Cleaning" wagons perminatly running with the springs removed so that it's just the weight of the cleaning pads on the rail tops. I also use some of thge Gaugemaster axel-hung pads.

Or another thing to consider is that maybe the Europeans use a better quality material for their tyres ?

 

I'd agree completely with this. The crud has to come from somewhere, and little of it can come from the tyres otherwise they'd vanish quickly to nothing.

 

What I do know from extensive purchases of British "OO" pre-owned, is that a good number of modellers have lamentable housekeeping. Ebay descriptions of "erratic running" are often explained simply by huge quantities of gunge on the wheels, and some too on the pick-ups, which makes you wonder how the previous owners think electricity conducts! I do accept that some of our RTR manufacturers have at times been guilty of excess lubrication at the factory, but is it really that difficult to do some focused cleaning with the likes of Slater's Track and Mechanism Cleaner and some cotton buds?

 

In Britain we seem to have a big "downer" on tender drives, perhaps because the offerings we had decades ago frankly weren't that great, and manufacturing of the locos was sufficiently rough to regularly give the phenomenon of driving wheels stuck and being pushed along. That doesn't seem at all to be the outcome with the likes of Roco and others, which frankly are in a different league.

 

John.

[34theletterbetweenB&D]

2 hours ago, GrumpyPenguin said:

...Or another thing to consider is that maybe the Europeans use a better quality material for their tyres ?

That's long been the case. It took me a while to realise that my now over 50 year old Rivarossi Big Boy has a pair of traction tyres, made in a translucent polymer which causes no appreciable rail dirt, and are still as good as ever after all this time. (The only failing of these traction tyres is ineffectiveness on a wet rail, what with me being the kind of yahoo that once ran his train set in the garden, but that's a common failing of all traction tyres.)

 

The general point you make is absolutely so: development of European HO has pursued reliable operation for the purchaser using the complete system the brand offers. Good heavens, the brands even explain in detail how to get the best from it; something largely notable by its absence in RTR OO. Every visit to our continental family left me filled with envy back in the 1960s... 

 

1 hour ago, Michael Hodgson said:

Traction tyres may have gone out of fashion for the latest locos, but a lot of us still run locos that have been around for a while...

Fully appreciate that this is the case for many.

 

My approach is different, I ceased buying RTR OO from first exposure to an MRC in my teens, and 'everything' was kit built from then on, until the first hints of HO mechanism  technique enabled by manufacturing in China were seen.

 

From my perspective the present RTR OO technique has delivered what I always wanted: RTR OO models made to competent kit builder standard enabling me to enjoy my primary interest in timetable operation, with no need to run the loco, carriage and wagon works. Very much a 'horses for courses' picture.

1 hour ago, Michael Hodgson said:

...traditional British loose-coupled goods trains, which do pick up one wagon at a time, and also come clanking one at at a time to a halt...

An aspect that I treasure, and accidentally enabled by the miniature tension lock as made to Bachmann's pattern, combined with the NEM coupler pocket. Still looking for an ideal solution for the steam era  fitted freight which should be buffered up, likely compromise, magnetic...

 

[kevinlms]

14 minutes ago, John Tomlinson said:

 

 

In Britain we seem to have a big "downer" on tender drives, perhaps because the offerings we had decades ago frankly weren't that great, and manufacturing of the locos was sufficiently rough to regularly give the phenomenon of driving wheels stuck and being pushed along. That doesn't seem at all to be the outcome with the likes of Roco and others, which frankly are in a different league.

 

John.

I expect the fact that traction tyres, along with the minimum possible number of pick ups had a LOT to do with that. How many millions of models of locos must have been made, that only picked up from 4 wheels - two on 1 bogie and two on the other for diesel & electric locos, or for steam 2 on one side plus 2 on the tender. All this regardless of how many wheels were on the loco!

 

The main makers of British models for a number of years, were Hornby & Lima, who were clearly in the business of making toys, predominately for children. Only later was adding pick ups to more wheels to became a standard practice. Once that was more or less settled, other improvements to the chassis and then the bodies started.

[DCB]

8 hours ago, kevinlms said:

I don't see why ANY DCC system can't do that. Use one controller to operate the train loco and a 2nd controller to operate the banker - DO NOT consist them.

 

As always, your statements suggest that basic DCC functions are harder than they really are.

Please  give  one example of a suitable controller or pair of controllers ,  where two  operators can operate Railway traction  similar to two cars being operated  on the same lane of a Scalextric Digital track.    

[kevinlms]

10 hours ago, DCB said:

Please  give  one example of a suitable controller or pair of controllers ,  where two  operators can operate Railway traction  similar to two cars being operated  on the same lane of a Scalextric Digital track.    

Perhaps you would be better off explaining why you don't think that DCC can do such a thing?

 

Just about any DCC set up has a 'Master' unit for want of a better term, to provide a command station, an interface if you like. Then you can use 1 or more controllers to actually control the trains, by dialling up their address - one per operator is best, although there are plenty of dual units too.

They don't even need to be identical units, as DCC is largely an industry standard with many suppliers.

 

I suspect that you believe that DCC is still the original Zero 1 or the Airfix system, with the limitations of such legacy systems.

[DCB]

1 hour ago, kevinlms said:

Perhaps you would be better off explaining why you don't think that DCC can do such a thing?

 

Just about any DCC set up has a 'Master' unit for want of a better term, to provide a command station, an interface if you like. Then you can use 1 or more controllers to actually control the trains, by dialling up their address - one per operator is best, although there are plenty of dual units too.

They don't even need to be identical units, as DCC is largely an industry standard with many suppliers.

 

I suspect that you believe that DCC is still the original Zero 1 or the Airfix system, with the limitations of such legacy systems.

 

It's the interface issue.  

 

But the real thing which irritates me is the  unrealistic operation DCC enthusiasts think is good. Full size Trains can't creep for extended periods unless Slow speed fitted for MGR operations , but they can stop to the nearest 6" or less so coaches never move when couping up.
I am working on sound,  So many  sound locos chuff like they are pulling 400 tons when running light.   Real ones usually give 4 or 8 chuffs then coast.

 

But its the  interface.  I want a speed control knob  Hand held  one handed.  ideally wireless.  Everything else can be on the console,  Whistle button would be nice 

[kevinlms]

OK, DCB. Keep going with your beliefs.

 

30 seconds on Google revealed this.

 

https://www.digitrax.com/products/throttles/ut6/

Edited April 21 by kevinlms
More info

[JDW]

I was going to reply to the original post, but slightly confused by the above off-topic drift. Both of my DCC systems have hand-held controllers with a dial that I can use in one hand, and neither under DC nor DCC operation have I ever found myself wanting to leave trains to creep along for some unexplained reason. I do like ones that will slow gradually through the speed range right to a stop, though, and remain smooth at slow speed. Sound, on the other hand, I find an irritating noise no matter how good it is (though I'll add that I admire the technical skill behind it).

 

Back to the original topic, besides the traction tyre debate, I'm surprised no-one has commented on the fact that the bogies are fixed. I know it's not a new model, and I know it makes it easier to engineer, but it's the kind of thing that I can't help feel that if it were a British prototype, we'd all be saying how terrible it was, unrealistic, a cheap solution, looks daft with the bogies not turning, and so on.   

[John Tomlinson]

12 minutes ago, JDW said:

I was going to reply to the original post, but slightly confused by the above off-topic drift. Both of my DCC systems have hand-held controllers with a dial that I can use in one hand, and neither under DC nor DCC operation have I ever found myself wanting to leave trains to creep along for some unexplained reason. I do like ones that will slow gradually through the speed range right to a stop, though, and remain smooth at slow speed. Sound, on the other hand, I find an irritating noise no matter how good it is (though I'll add that I admire the technical skill behind it).

 

Back to the original topic, besides the traction tyre debate, I'm surprised no-one has commented on the fact that the bogies are fixed. I know it's not a new model, and I know it makes it easier to engineer, but it's the kind of thing that I can't help feel that if it were a British prototype, we'd all be saying how terrible it was, unrealistic, a cheap solution, looks daft with the bogies not turning, and so on.   

 

I take your point, but on the real thing the actual swivelling of the bogies would be indiscernible as real railway curves are far less sharp than we use on our models.

 

The other thing, and I confess some ignorance here, I'm sure that on some German tenders the apparent bogies weren't bogies at all as we understand them, simply fixed frames. IIRC this was true on the Br52 Kriegsloks for one. I'm happy to be contradicted on this as I don't speak German and have struggled to understand the literature, so may be wrong.

 

John.

[JDW]

1 minute ago, John Tomlinson said:

The other thing, and I confess some ignorance here, I'm sure that on some German tenders the apparent bogies weren't bogies at all as we understand them, simply fixed frames. IIRC this was true on the Br52 Kriegsloks for one. I'm happy to be contradicted on this as I don't speak German and have struggled to understand the literature, so may be wrong.

 

 

 

Interesting, I didn't know that, thanks for taking the time to point it out. I do speak German, but am neither a steam nor German railway fan! 

 

1 minute ago, John Tomlinson said:

I take your point, but on the real thing the actual swivelling of the bogies would be indiscernible as real railway curves are far less sharp than we use on our models.

 

Fair point, though given some of what 'we' seem to want on models which would be barely discernible if properly scaled down, swivelling bogies (if they should indeed swivel) would seem like a basic ask! (Over-bright lights are the first that come to mind!)

[jjb1970]

Years ago I had a Roco kettle with a shaft drive from the tender to the locomotive wheels, a bit like the system Dapol used in N but more discrete as the shaft was under the footplate.

 

At one time, up to the late 90's British OO was woeful compared to European HO but these days I don't see that British models lose anything to overseas models. I was a keen enthusiast of German, Swiss and Italian outline for many years at a time when they really did make British models look awful but I  drifted back to British as standards improved, through retained an interest in North American and in recent years have been primarily interested in Japanese and Chinese models.