Run time

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artfull dodger
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Re: Run time

Post by artfull dodger » Wed Feb 06, 2019 4:30 pm

Excellent run times of your Billy! Keeping the safety from wasting steam from lifting or weeping is key to long run times, just as keeping the gas turned right down.So many have no clue about this and steam around the track with the burner roaring and the safety lifted. Learning each engines quirks and mannerisms is part of the fun and the lure of live steam. These little beasts are alive, just as the old timers drivers described full size locomotives back in the glory days of steam. Then you take the next step and add a goodall or boiler refeed valve. Then you can remain in steam all day if you so desire, topping up water, steam oil and gas as needed. Spending your time at station stops tending your engine just as the driver and fireman do in 1:1 scale. Life is great!
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Re: Run time

Post by CSL » Fri Feb 08, 2019 4:41 pm

Interesting thought about the pop safety valve - I hadn't thought of that and it does rather appeal.

On the other hand, with a ground-level/slightly raised railway and young children about, maybe not quite yet!

My Bertie is basic spec - no pressure gauge, so a bit tricky to keep to a particular low boiler pressure.

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Re: Run time

Post by artfull dodger » Fri Feb 08, 2019 8:04 pm

The upgrade "pop" style safety valve just prevents the steam wasting from a valve that by design doesn't seal well so it wisps steam constantly instead of releasing at a specific pressure then resetting till pressure rises again. Ground level or raised doesn't matter much. Upgrading Bertie with the options like a pressure gauge, water top up and sight glass really make a basic engine better than some of the older classic range models from Roundhouse that cannot have a sight glass by design at this time. I took a Sammie and changed the valve gear from slip eccentric to Walschearts with the kit from Roundhouse. Mike
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Re: Run time

Post by Tom the blacksmith » Fri Feb 08, 2019 8:14 pm

CSL wrote:
Fri Feb 08, 2019 4:41 pm
Interesting thought about the pop safety valve - I hadn't thought of that and it does rather appeal.
I thought exactly the same, I've noticed a fairly constant weeping from the RH safety valve. Are there any equivalent replacements available this side of the pond?

Lovely conversion on your Sammie Mike :thumbup: :thumbup:

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Re: Run time

Post by tom_tom_go » Fri Feb 08, 2019 8:54 pm

Tom the blacksmith wrote:
Fri Feb 08, 2019 8:14 pm
I thought exactly the same, I've noticed a fairly constant weeping from the RH safety valve.
When you say it constantly weeps at what pressure (and is your pressure gauge working accurately?).

On a gas loco you should be able to easily control the pressure without the safety valve going off once the loco is settled into the run.

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Re: Run time

Post by Tom the blacksmith » Fri Feb 08, 2019 9:18 pm

Sorry Tom, I didn't explain it well, it's not that it's blowing off all the time as if boiler pressure is too high or that the valve pressure was set incorrectly it just wisps steam fairly constantly. It doesn't really bother me, and I never really thought about it until Mr Dodger mentioned it.

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Re: Run time

Post by tom_tom_go » Fri Feb 08, 2019 9:21 pm

Take it apart and clean it, might have dirt or scale in it so not seating properly.

Failing that, contact Roundhouse and they should send you a replacement.

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Re: Run time

Post by CSL » Fri Feb 08, 2019 11:28 pm

artfull dodger wrote:
Fri Feb 08, 2019 8:04 pm
Upgrading Bertie with the options like a pressure gauge, water top up and sight glass really make a basic engine better than some of the older classic range models from Roundhouse that cannot have a sight glass by design at this time. I took a Sammie and changed the valve gear from slip eccentric to Walschearts with the kit from Roundhouse. Mike
Bravo! Not sure I'll ever get to that level.

I assume that if you fit the WeeBee safety valve the Roundhouse dome won't fit over it?

It seem that artfull dodger and tom_tom_go have completely opposing views on the practical effect* of replacing the Roundhouse safety valve!

*As opposed to the prototypical aesthetics of the pop 'n' shut function, which I doubt there's much disagreement over.

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Re: Run time

Post by artfull dodger » Sun Feb 10, 2019 6:42 pm

I use the safety valve made by Wee Bee Locomotive works, which is sold thru "The Train Department" website and shipped world wide. Available in many different pressure settings. According to the builder of the valves, who is also the leader of our local steam group, is the design of the RH valve that is prone to leaking as it relys on a O ring design. And while it does what is needed and does it well. Any steam leakage be it from the packing on the throttle shaft to the safety is wasteful and can reduce the run time. At a steam up with all the background noise, I have trouble getting my gas turned right down to keep even a proper pop valve from popping off constantly. Thats due to me being autistic and the noise overload overwhelming trying to hear the burner noise. Now on my 2 Regner models with thier noisy burners, when turned down to proper level I can still hear them. The Roundhouse FX gas system is really nice and really quiet when turned right down after initial start up and pressure raising.
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Re: Run time

Post by CSL » Sun Mar 17, 2019 7:03 pm

I got 30 minutes or so from the Bertie on a light load this afternoon, which would seem to be all right.

One thing though: it does seem to take at least ten minutes (of the run time, after pressure has built up) before it settles down to smooth and steady unattended running.

Obviously part of that is down to the gas tank heating up so the steam regulator needs to be adjusted downwards, but is my experience typical or am I doing something wrong?

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Re: Run time

Post by Keith S » Mon Mar 18, 2019 3:30 pm

The best part of a run is the middle bit. What happens is the gas tank slowly heats up, and as it does, provides a higher gas pressure to the burner. If you want to maintain a steady steam pressure you need to continuously turn down the gas for the first part of the run.

Meanwhile, you've started with a relatively full boiler. Since Roundhouse engines don't have a steam dome, the only place for steam to accumulate is along the top of the boiler where you've left some space. The smaller this space, the less well-behaved your locomotive will be. Obviously there's "priming" in which the loco will get some liquid water into the steam pipe, especially if the boiler's too full. But also, as the loco uses steam, it causes the pressure to drop momentarily in the steam space at the top of the boiler. The water then boils a bit and makes up the pressure. In equilibrium, I suppose the steam being drawn off by the cylinders and the steam being produced by the water boiling would be the same, but in reality the amount of pressure being drawn off by the cylinders changes continuously as the engine rounds curves and rolls across bumps, slowing down and speeding up. As the run progresses, the larger steam space in the boiler makes this process smoother because there is more steam accumulated there and it reacts better to small changes in pressure. Like the accumulator in a hydraulic system, if you're familiar with that. Anyway, at the middle of the run the gas tank has reached a steady temperature and your boiler is half full of nice springy steam rather than angry boiling water. That's why it behaves better. On a more comp,ex model with an axle pump and coal fire, you could keep it like that indefinitely, but on our little gas-fired contraptions, you notice all the effects of a boiler that is too full, just right, and too empty in one run!

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Re: Run time

Post by IrishPeter » Mon Mar 18, 2019 3:49 pm

One reason I have a soft spot for pot boilers is that their 'sweet spot' in terms of running is much larger than that of the single flue, internally fired, types. The down side is that they are appreciably less efficient. My Millie will chug away happily for 30-35 minutes after the initial temper tantrums caused by priming have subsided. I tend to use the Millie on the S&CLR&T when I want a low stress trundle.

I am currently trying to work out what my next move will be in terms of motive power as I need a locomotive that will run on 32mm for the Far End Tramway. I am heading towards either a Bertie, though I am also giving some consideration to Accucraft's Edrig replacement, or kit building a Roundhouse 'George.' The Far End Tramway is going to be a bit of an exercise in mountaineering, so I am going to have to choose wisely.

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Traffic Pattern? What pattern? Spuds out; grain in, but cattle, sheep and passengers are a lot less predictable.

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Re: Run time

Post by Chris Cairns » Mon Mar 18, 2019 5:35 pm

CSL wrote:
Sun Mar 17, 2019 7:03 pm
I got 30 minutes or so from the Bertie on a light load this afternoon, which would seem to be all right.

One thing though: it does seem to take at least ten minutes (of the run time, after pressure has built up) before it settles down to smooth and steady unattended running.

Obviously part of that is down to the gas tank heating up so the steam regulator needs to be adjusted downwards, but is my experience typical or am I doing something wrong?
Sounds normal to me. I find that the gas tank heats up more on my Bertie than other similarly mounted Roundhouse locos, so have to keep turning the gas down several times during a run. One thing I was not aware of until a discussion over on Facebook last year is that the Bertie has a high centre of gravity with more weight on the rear axle thus can be prone to centrifugal force rollovers on tight curves - mine has done it twice now.

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Re: Run time

Post by Chris Cairns » Mon Mar 18, 2019 5:43 pm

IrishPeter wrote:
Mon Mar 18, 2019 3:49 pm
One reason I have a soft spot for pot boilers is that their 'sweet spot' in terms of running is much larger than that of the single flue, internally fired, types. The down side is that they are appreciably less efficient. My Millie will chug away happily for 30-35 minutes after the initial temper tantrums caused by priming have subsided.

Peter in Va
In my experience, given the right conditions, I find the FX burner in combination with the fully enclosed combustion chamber, can be more efficient than the FG burner. Last year at a cold indoor venue my pre-owned 2002 Millie put in an impressive 63 mins run on one fill of mixed gas pulling 1 short coach on an out & back layout, running round at each end. Later in the year it ran for 53 & 55 mins on one fill of mixed gas on a Faller eTrain layout at an indoor model railway show.

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Re: Run time

Post by cncmodeller » Sat Mar 23, 2019 12:45 pm

I think 25 minutes is OK, I'm not a great fan of Gas fired locos I have three, to my mind they seem too fierce and too hot however much you try and turn them down,
and it always seems to me that you are trying to run a loco sedately while the boiler is bursting at the seems eager to charge around at full pelt and consequently you lose a lot of water so you are 'pressured' [excuse the pun] in pumping more water in at the earliest opportunity, so I wouldn't worry about the time per boiler fill.

John.

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