DCC, sound and free-running gearboxes

[SteveO]

I have a question or two. I don't know anything about how DCC works in detail but I plan to use it in my loco fleet.

My question is, if I have a DCC sound-equipped loco with a coasting gearbox, like an ABC for example, what will happen to the sound if I turn the throttle full off but the loco is still coasting? I imagine the engine will idle along but will the brake noise come on too – does the chip recognise that there is no power applied but the loco is still moving, therefore a brake noise needs to be made? Is this a function of normal DCC sound or is there a separate brake noise button?

I'm also assuming that I can program an acceleration curve into the chip so I can set off a loco at a prototypical acceleration rate instead of lurching into action and spilling the teas of First Class passengers? And if I can program an acceleration curve, will the engine noise be louder or deeper if I set the speed at a higher rate in lieu of it reaching that preset speed?

I'm not sure if I've made myself clear on a couple of those points so I'm happy to elaborate if needed.
Cheers!

 

[Simon]

I don't know the answer to your question 1 but observe that you wouldn't "drive" a DCC powered loco in the way that you describe, (you actually can't, unless you press the "kill" button which will nadger the sound immediately) the chip/system/whatever (you can see I'm really technical about these things) has inertia built in to it under normal control and the sound will "follow" smoothly whatever(ish) the throttle setting.

My guess is that the back emf etc from the still revolving motor would drive the sound irrespective of the throttle setting forany slight "lag" that occurred.

You can certainly set different speed curves on CVwhatever, Dr. Steph will probably be along shortly to give a proper answer

Simon

PS just buy a Multimaus and get playing

 

[Osgood]

Great questions and I'll be very keen to see the answers too, but can I start a bit further back - like what is a 'coasting gearbox'? I assume it has an over-run clutch to allow freewheeling?

Not come across these but guess there would then be no dynamic braking at all from the motor, therefore braking is non-existent? And what about reversing?

If you cannot achieve the desired results by electronic electrickery, how about the following idea?

The DYNADRIVE 'fluid coupling' has been mentioned on here before I think - but perhaps the ideal to replicate the delay between genset revving up and train accelerating would I guess be something like a soft fluid coupling that will allow considerable slip under acceleration (the dynadrive locks up when revs rise above 'idle') and also slowing of motor before train starts to decelerate.

Now there's a miniaturisation challenge!

 

[Dog Star]

We have a GWR pannier tank which is fitted with a SWD sound chip. If, when running at speed, the regulator is "shut" (set speed control back to zero or whatever) then the exhaust beat stops immediately and the remaining sounds are those of a coasting matchbox - which is just why we bought this sound decoder.

regards, Prof Barking (who is Mad and not a Prof. DCC with CDM)

 

[SteveO]

PS just buy a Multimaus and get playing

Got one! I have the red one (not wireless, unfortunately) in a box in the loft waiting for me to get my A into G...

... what is a 'coasting gearbox'? I assume it has an over-run clutch to allow freewheeling?

The normal worm/wheel arrangement doesn't allow you to 'push' the loco along as the wheels are locked unless powered by the motor. A gearset that uses helical and spur gears would allow it to be pushed along without power, and coast to a stop (or roll over dirty/unpowered track) plus the arrangement is much more efficient at converting power.

The DYNADRIVE 'fluid coupling' has been mentioned on here before I think - but perhaps the ideal to replicate the delay between genset revving up and train accelerating would I guess be something like a soft fluid coupling that will allow considerable slip under acceleration (the dynadrive locks up when revs rise above 'idle') and also slowing of motor before train starts to decelerate.

Now there's a miniaturisation challenge!

That sounds like a fab idea! I'd love to see one but I'd imagine they'd be big and expensive...

We have a GWR pannier tank which is fitted with a SWD sound chip. If, when running at speed, the regulator is "shut" (set speed control back to zero or whatever) then the exhaust beat stops immediately and the remaining sounds are those of a coasting matchbox - which is just why we bought this sound decoder.

That sounds (<– pun) just like what I'm after but in diesel form. Dod you know if SWD has a similar diesel soundchip? What gearbox do you have on it or is all of the coasting done with DCC?

 

[Dog Star]

We have a GWR pannier tank which is fitted with a SWD sound chip. If, when running at speed, the regulator is "shut" (set speed control back to zero or whatever) then the exhaust beat stops immediately and the remaining sounds are those of a coasting matchbox...

That sounds like what I'm after but in diesel form. Do you know if SWD has a similar diesel soundchip? What gearbox do you have on it or is all of the coasting done with DCC?

Um, no...
ABC with helical gears...
Do not know... (help, Steph!)

regards, Graham the un-expert (in DCC matters)

 

[Simon Dunkley]

Steve,

You have what is generally referred to as a spur-gear gearbox: free-coasting would imply the use of some kind of clutch between motor and a flywheel to most people. You will get a degree of overrun that is greater than with a worm and wheel arrangement, but not the same as you would with, say, a Dynadrive arrangement.
There is no issue with DCC in respect of spur gear drives directly connected to the motor.

What you are talking about is having a more sophisticated sound profile than simply matching the motor. I cannot speak for SWD, but have had some experience with the Digitrainsounds profiles produced by Paul Chetter and sold by Digitrains (usual disclaimer). These strike me as being exactly what you are looking for, straight out of the box.

In essence, acceleration and deceleration have been programmed in, but if you slowly reduce the speed setting on the controller, the loco will "coast" until the deceleration curve has brought the loco speed down to that set by you. A more rapid deceleration will introduce break sounds, and there is also a braking function programmed into the chip set, along with sundry other noises. There is also a function setting to increase the volume to suggest an engine working harder.

What you can do, then, is to set a loco to the light loading for sound, back it down onto a train and brake it so that you get break squeal, and then press a function button to produce a buffer-clanking sound, followed by the sound of a coupling being dropped over the hook. You then set the loco sound to be a heavy load, press a function key to provide the guard's whistle, then the loco whistle and start the engine off. It will slowly accelerate and sound as if it is working hard. Once it reaches the set speed (this may be low, through the station throat) the sound will lessen slightly, until clear of the station and accelerating again. In addition, if you have a steam loco fitted with a Westinghouse pump, you can pump up the air after coupling up, etc.

As I said, have a look at the Digitrainsound files on the Digitrains website. They produce a class 31 sound file for both Zimo and Loksound decoders.

 

[SteveO]

Thanks Simon, that looks to be the perfect solution!

 

[Simon]

I've just bought a Paul Chetter Steam sound for my S&D 2-4-0 and look forward to playing with it based upon others' reports and what Simon D has said about it.

Red Multimauses are good, I've got one of those too

Simon

 

[Simon Dunkley]

Agreed, Jordan, that this is one route.
However, what Paul has done is to set this up already. Only available on Zimo and ESU, though. I don't think Soundtraxx want people fiddling with their sound files!

 

[Steph Dale]

Graham, Steve,
The inertial effect in the sound set of the decoder is a pretty standard trick with ESU, in terms of diesels both Howes and SWD decoders tend to get this right. And 'right' doesn't necessarily mean 'what you expect'; many early diesels load the main generator without increasing revs, so move off before throttling up. Hydraulics tend to behave differently again and even the driving conventions of nominally the same power system differ between the UK and Germany. ESU had different mode settings for different loco types; electric, diesel-mechanical, diesel-hydraulic, diesel-electric and steam, IIRC.

I don't know too much about Zimo as I've tended to regard the ESU LokSound decoders to be the bee's knees. To the point where I bought the LokProgrammer so I can load and fiddle my own sound profiles.

Steph

 

[Simon]

I don't know too much about Zimo as I've tended to regard the ESU LokSound decoders to be the bee's knees. To the point where I bought the LokProgrammer so I can load and fiddle my own sound profiles.

Ah, just the man!

I'd like "Men of Harlech" in a lusty baritone please, your choice of function key

Simon

 

[Dog Star]

What I did to enable 'coasting' sounds on one of my diesels was to set the engine sounds to 'Manual Notching'; F9 revs up the engine and F10 drops it back down, regardless of actual loco speed. It's a nice effect to be able to rev the engine before the loco starts moving, as if it's taking the strain of the load, and later when moving, drop the engine speed for that coasting effect...

Sounds nice given that the only way to drive a Wezzie is flat out, even when the train is still in platform 1 at PDN. Now, getting a DCC CV for rocking the loco on the bogie pivots just before take off, that is going to be just so.

 

[Steph Dale]

Ah, just the man!

I'd like "Men of Harlech" in a lusty baritone please, your choice of function key

Simon

No problem, my 'signature' is an old Nokia ring tone, deployed when anyone accuses me of being serious. Or in the presence of video cameras!

Sounds nice given that the only way to drive a Wezzie is flat out, even when the train is still in platform 1 at PDN. Now, getting a DCC CV for rocking the loco on the bogie pivots just before take off, that is going to be just so.

Another problem to talk through on Saturday?

Steph

 

[SteveO]

Sounds nice given that the only way to drive a Wezzie is flat out, even when the train is still in platform 1 at PDN. Now, getting a DCC CV for rocking the loco on the bogie pivots just before take off, that is going to be just so.

You could mount a small motor with an off-centre flywheel in there that rotates fairly slowly to imitate rocking? But this would leave the virtual passengers with a social etiquette problem, as the old saying goes, "When the wagon's rockin' don't come knockin'"...

 

[Dog Star]

... this would leave the virtual passengers with a social etiquette problem, as the old saying goes, "When the wagon's rockin' don't come knockin'"...

Not quite the behaviour I was trying to describe... when power was applied from a stand a Wizzo would kind of sit down on the rear bogie, rock onto the front one and then take off... like a rocket,

Never seen an explanation of this behaviour although I suspect that the origin must lie in weight transfer under extreme torque... maybe Ian can help.

regards, Graham

 

[Railwaymaniac]

..... although I suspect that the origin must lie in weight transfer under extreme torque... maybe Ian can help.

regards, Graham

Ian is impressed, depressed, and taking notes on how to insult someone twice in the same sentence . . . . . . .


Ian

 

[Dog Star]

Not quite the behaviour I was trying to describe... when power was applied from a stand ...

Never seen an explanation of this behaviour although I suspect that the origin must lie in weight transfer under extreme torque... maybe Ian can help...

Ian is impressed, depressed, and taking notes on how to insult someone twice in the same sentence...
Ian

One of the changes to WT which arise as a result of (a) getting to know people outside of the 'net and (b) increasing use of christian names is the potential for confusion. Actually WT is full of confusion from postings of a small contingent of "regulars". In this case, I was referring to Ian, otherwise known as Boris or D1054 rather than Ian otherwise known as Ian. My apologies Ian - there, sorted that .

I was talking to Steph, otherwise known as Steph, at the Aylesbury Show about the rocking Wizzos and the conclusion was uncertain... nothing unusual there then. Maybe Ian of Happy Hydraulic Honley can explain how the effect of starting torque on cardan shafts / gearboxes is dealt with?

regards, Graham

 

[Phill Dyson]

One of the changes to WT which arise as a result of (a) getting to know people outside of the 'net and (b) increasing use of christian names is the potential for confusion. Actually WT is full of confusion from postings of a small contingent of "regulars". In this case, I was referring to Ian, otherwise known as Boris or D1054 rather than Ian otherwise known as Ian. My apologies Ian - there, sorted that .

When using the christian name of a member who is known to others by a forum name it's helpful to put the forum name in brackets such as Ian (1054) or Boris (1054)

Phill (onslaught832) (832onslaught)

 

[Simon Dunkley]

When using the christian name of a member who is known to others by a forum name it's helpful to put the forum name in brackets

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