Rhb G 3/4 - Getting the right 'Chuff'

[curtis]

I'm in the process of upgrading my LGB 20272 (Heidi) - part of this involves adding an axel-based clock to correctly time the sound effects. I'm doing this using the Mxion clock sensor. I have it working but I'm trying to understand a couple of things to get the right cadence of the 'chuff'. Unfortunately, I don't have the technical understanding of the real prototypes to know the right configuration and my searching didn't turn up an answer.

My questions:

• Is the G 3/4 a 2 stroke or 4 stroke? (and for future reference, how can I understand this about a locomotive?)
• For a 2 stroke locomotive, I understand the opposite wheels are 1/4 turn out of alignment to stop a situation where they would lock perfectly in 180 and stop the cylinders on the push/pull), if so, does this mean my magnets should also be placed 1/4 turn from each other to simulate the chuff correctly?

If I've used any terminology incorrectly here, please do let me know but I hope I've articulated myself well enough?

Curtis

 

[curtis]

I was over complicating this. Found a YouTube video and counted the 'chuffs' per wheel rotation. It was 4

 

[dunnyrail]

I was over complicating this. Found a YouTube video and counted the 'chuffs' per wheel rotation. It was 4

With a 2 cylinder locomotive you get 4 chuffs per revolution of the wheeks. Each cylinder does 2 chuffs per revolution, one on the forward movement of the cylinder the second on the return movement. The chuff is the exhausted steam escaping to atmosphere as the valve events let it escape.

 

[K B Lager]

I'm in the process of upgrading my LGB 20272 (Heidi) - part of this involves adding an axel-based clock to correctly time the sound effects. I'm doing this using the Mxion clock sensor. I have it working but I'm trying to understand a couple of things to get the right cadence of the 'chuff'. Unfortunately, I don't have the technical understanding of the real prototypes to know the right configuration and my searching didn't turn up an answer.

My questions:

• Is the G 3/4 a 2 stroke or 4 stroke? (and for future reference, how can I understand this about a locomotive?)
• For a 2 stroke locomotive, I understand the opposite wheels are 1/4 turn out of alignment to stop a situation where they would lock perfectly in 180 and stop the cylinders on the push/pull), if so, does this mean my magnets should also be placed 1/4 turn from each other to simulate the chuff correctly?

If I've used any terminology incorrectly here, please do let me know but I hope I've articulated myself well enough?

Curtis

When finished to your satisfaction please post a short description of all the electronics used and method of installing them for i run a ‘dumb’ Heidi too.

 

[mike]

Having set a loco up to 4 beats per revolution..it just sounds too fast to me ..so I re set it to two..

 

[dunnyrail]

Having set a loco up to 4 beats per revolution..it just sounds too fast to me ..so I re set it to two..

Many say that, I think it very much depends on the speed that you run. As my line’s prototype is a 20kph line 4 beats sounds just fine. All my DCC locomotives set to around that scale speed, Fosworks with Cobra speed control set to slowest speed max which is about right in most cases.

 

[curtis]

I can put together a bit of an overview. This was it on mainline trials yesterday evening.

I'm also not sure about the amount of chuffs - feels too many but perhaps I'm running too fast!

 

[tac foley]

I can put together a bit of an overview. This was it on mainline trials yesterday evening.

I'm also not sure about the amount of chuffs - feels too many but perhaps I'm running too fast!

Apart from the odd 'missing' chuffs, the rest of it sounded just fine.

 

[tac foley]

This is the Phoenix sound system in the Bachmann K27 behind my Accucraft version, taken a few years back on the layout of a friend near Leicester. It has a similar chuff-counter - a Hall sensor on one axle - to match the speed with the action of the locomotive.

I just wish there was an affordable sound system now that Sierra has gone the same way - oblivion. Until I had my K27 converted to digital r/c, it was analogue, and used a flat acid battery to power the sound system. That Sierra system had the following features -

1. Boiler hiss when stationary, with occasional feedwater pump operation. Also a 'phantom' fireman shovelling coal

2. On opening the 'throttle', two toots and a bell, until about 5mph, when the bell stopped and the chuffs continued in perfect harmony with the action of the pistons.

3. The whistle exactly replicated 'mournful moosie' of the real #453.

4. Slowing to a stop, the bell sounded until the loco stopped, whereupon there was a single 'toot', and #1 recommenced.

5. Going into reverse, three toots and the bell, just like the real thing.

6. Installing r/c took all that away, as the vendor told me that a. the batteries were no longer available, and b. it was not compatible with the new digital system.

I've never been happy with the 'new' sounds from a well-known and very popular brand of sound system, although is does have the useful 'drifting' facility. The whistle is a very poor rendition of the real deal, having no 'quilling' effect whatsoever - a VERY prominent feature of the real Colorado three-footers.

 

[K B Lager]

I can put together a bit of an overview. This was it on mainline trials yesterday evening.

I'm also not sure about the amount of chuffs - feels too many but perhaps I'm running too fast!

Good sound effects. I agree with Dunnyrail about running at a “scale” 20 kph in order to appreciate the 4 chuffs per steam cylinder timing.
Martin Fisher in his book “Swiss Steam Locomotives since 1900” published by Swiss Express Publications stated the maximum speed was 45 kph (on the level I presume). The line up to Davos is far from level so with 2-3 old coaches 20 kph is about right and going back down through Klosters to Landquart I would not want to be a passenger at any higher speed!
The author also states that locos 3,4 & 5 of the first SLM production batch of 1895 were sold to the Prinz Heinrich Bahn of Luxemberg, running there to 1954. Maybe the pirate Pugwash may know if any were preserved in the Grand Duchy.

 

[mike]

I can put together a bit of an overview. This was it on mainline trials yesterday evening.

I'm also not sure about the amount of chuffs - feels too many but perhaps I'm running too fast!

That's what I ment, you can crawl ,but it looks too slow, or move slowly, but sounds wrong.. getting the balance between the two .= For me, 2 beats per revolution

 

[Paul M]

I'm not sure if it's just me, but all videos of our engines look like we're driving them like Nigel Mansell,

 

[dunnyrail]

I can put together a bit of an overview. This was it on mainline trials yesterday evening.

I'm also not sure about the amount of chuffs - feels too many but perhaps I'm running too fast!

I think we need to see a slower speed pass of a station with sideways following view at same standard speed. Super clean track for a few yards will help. I check speeds with my ‘Model Speed’ iPhone app that appears to be unavailable now.

At the start of the vid speed was about right, register that on your hand control. To my mind there were times where there appeared to be 3 beats and others with possibly 4. Perhaps something not quite right in the sensor area with activations being missed?

 

[David Price]

I'm not sure if it's just me, but all videos of our engines look like we're driving them like Nigel Mansell,

Would have to agree with you Paul - very few people appear to run narrow gauge engines at prototypical speed - whether live steam or battery power This is one of my two pet hates - the other is the lack of weathering.

Having just climbed off driving this pulling a 300 ton train on a 3'6" heritage railway I can state categorically we don't run anywhere near the speed our 32mm or 45mm gauge 16mm/Fn3 locos would be running at if they were 12" to the Foot scale:



And as for timing the exhaust beats I find the best way is to run the engine on a rolling road (I do this in both 1:48 and Fn3 scales) and watch the cross heads - 1 beat for each direction for each side (gets interesting with three cylinder Shays).

I use ESU decoders on the Fn3 stuff (Loksound 5XL with CVP Airwire control) and am happy with the exhaust beats on both the Mallet & the Shay after using the LokSound programmer. These are the only two I have done so far in Fn3 (having only got into this scale) - more to come:



This shot was taken at the Victorian AMRA Open Day (which was primarily European this year) but the Mallet does get a look in around the 19 minute mark of the Youtube video:

The public liked both the sounds of the Mallet & the Shay - and the weathering!

I base a lot of my work on working so closely with the real thing - you get a lot of time to look at details when you are lighting up and prepping an engine like this:



Gauge 1 live steamers tend to run at prototypical speeds:

My favorite so far is this clip:

Love the subtle weathering on the Big Boy - and the scale speed it runs at (and actually has an exhaust beat).

So my plea to many of you out there - slow down - and maybe even apply a little bit of weathering.

Oh and while I'm on my soap box - proper scale figures work well for me instead of some of the caricatures I see on the footplate:



The driver and fireman are 1:20.3 figures from Andian Models (NSW Australia) - my other go-to is Model-U in the UK. Both are so much better than anything from Bachmann and other sources (if you like crew that look like real people that is).

Cheers

 

[Paul M]

Would have to agree with you Paul - very few people appear to run narrow gauge engines at prototypical speed - whether live steam or battery power This is one of my two pet hates - the other is the lack of weathering.

Yes, but the videos of our steam ups seem to show the trains moving at a fat faster rate than they actually were, it seems the process of filming has speeded things up!

 

[David Price]

Hi Paul,

I would have to disagree that the videos are speeding things up - this was the case when people shot Super 8mm film at 18fps to extend the use of a 50' load and then transferred it to video at 25fps (PAL - UK & Australia) or 29.97fps (NTSC - US) but unless YouTube is doing something very peculiar I believe what you see is an accurate playback frame rate. (I spent 45 years in the Film & Television industry specializing in broadcast post-production and feature film visual effects software before I retired).

If you watch the AMRA video the two live steam trams that George built are running as fast on screen as they were on the day - likewise the electric European LGB, Piko and other stuff. Watch the set coming through the points at the twenty minute mark - if to scale that train would quite likely derail. My Mallet and Shay were the only two that were run to scale - the Shay doesn't feature in the video as it only got in a couple of laps due to its slow speed!

I am relatively new to this scale but the problems lie in several areas - if you are running track power and set a particular speed you have little or no ability to adjust the speed when the train is out of site of the controller (which is why I have chosen to go with radio control).

Similarly with live steam unless under radio control - once they are out of physical contact range to adjust the throttle little tank engines seem to be run at what would be 40 to 50mph in reality (this did occur on rare occasions on our 2' lines but the Victorian Narrow Gauge 2'6" lines were "Speed Limit 20" (mph).

In the smaller live steamers the cylinders are so inefficient at low speeds you have to run them faster than the prototype to actually get them to work unless it is a geared locomotive like a Climax or Shay. Even Regner's Heisler appears to run faster than the prototype which, albeit the fastest of the geared locomotives topped out at 15mph. George's steam trams seen on the AMRA video (see four of them on the Great Southern Steam Up YouTube) are actually geared down between the double acting oscillators and the wheels.

The only solution to this with the small stuff appears to be either hide a gear reduction in the drive train as a number of UK builders have done over the years (mainly for oscillators) or install an Australian built slo-mo (which I believe is no longer in production).

 

[dunnyrail]

Hi Paul,

I would have to disagree that the videos are speeding things up - this was the case when people shot Super 8mm film at 18fps to extend the use of a 50' load and then transferred it to video at 25fps (PAL - UK & Australia) or 29.97fps (NTSC - US) but unless YouTube is doing something very peculiar I believe what you see is an accurate playback frame rate. (I spent 45 years in the Film & Television industry specializing in broadcast post-production and feature film visual effects software before I retired).

If you watch the AMRA video the two live steam trams that George built are running as fast on screen as they were on the day - likewise the electric European LGB, Piko and other stuff. Watch the set coming through the points at the twenty minute mark - if to scale that train would quite likely derail. My Mallet and Shay were the only two that were run to scale - the Shay doesn't feature in the video as it only got in a couple of laps due to its slow speed!

I am relatively new to this scale but the problems lie in several areas - if you are running track power and set a particular speed you have little or no ability to adjust the speed when the train is out of site of the controller (which is why I have chosen to go with radio control).

Similarly with live steam unless under radio control - once they are out of physical contact range to adjust the throttle little tank engines seem to be run at what would be 40 to 50mph in reality (this did occur on rare occasions on our 2' lines but the Victorian Narrow Gauge 2'6" lines were "Speed Limit 20" (mph).

In the smaller live steamers the cylinders are so inefficient at low speeds you have to run them faster than the prototype to actually get them to work unless it is a geared locomotive like a Climax or Shay. Even Regner's Heisler appears to run faster than the prototype which, albeit the fastest of the geared locomotives topped out at 15mph. George's steam trams seen on the AMRA video (see four of them on the Great Southern Steam Up YouTube) are actually geared down between the double acting oscillators and the wheels.

The only solution to this with the small stuff appears to be either hide a gear reduction in the drive train as a number of UK builders have done over the years (mainly for oscillators) or install an Australian built slo-mo (which I believe is no longer in production).

See post #4 on this link.

Post in thread 'Slow Speed Control of Live Steam, SloMo one answer, after the demise of SSP Wilson Locomotives takes over the make'

27 Aug 2024

Taking inspiration by a member of a german forum, I built myself a slomo with elicoidal gears, that are a bit more expensive but quieter:

That looks very good, I imagine a self built one would cost less than a bought on at around €500 the last one I got.

• dunnyrail

 

[David Price]

With the exchange rate as it is a Brian Wilson's Slo-mo at AUD$425 is a pretty reasonable purchase I suspect if you have a Roundhouse locomotive. (about GBP220 plus postage).

SSP Slomo

www.wilsonlocomotives.com

 

[dunnyrail]

With the exchange rate as it is a Brian Wilson's Slo-mo at AUD$425 is a pretty reasonable purchase I suspect if you have a Roundhouse locomotive. (about GBP220 plus postage).

SSP Slomo

www.wilsonlocomotives.com

I agree, even when I got mine some years back the price appeared well worth the cost for the improvement gained. I think I got 2 of my 3 ordered separately without getting hit for add on’s.