Regulating fire mass

[sidneyschwartz]

I've been working on driving a steam loco with the "auto fireman" function turned off. So far, so good, mostly. I have a few questions.

1. If I have an "ideal" fire mass of, say, 68%, how far down do I let that go before adding to it? Is there a rule of thumb, or does it depend entirely on what the boiler pressure is doing?

2. If I'm running at speed with the cut off turned way down, and the pressure is still building, is it better to let the relief valves blow, or to increase the cut off so more steam is being used and lower the pressure that way?

3. Is there any reason I shouldn't be adding coal and water at the same time?

[Chicken Balti]

Hello sidney, firing is all about having plenty of steam when your driver requires it and a cooler fire with less steam generation when you don't.
When you get to know your route gradiants and steam engine after practice, that comes a lot more easy to balance out. In real life, you only add coal to the fire when the regulator is open. Logical if you think about it, no point in adding coal to the fire, if the driver does not require more steam. However, if you have allowed your fire mass to drop too much, you will have to add coal.
A good fireman with years of experience, will be able to keep full boiler pressure all the time, without lifting the safety valves fully (called 'feathering') regardless of how hard the engine is working. Adding coal 'little and often' as we say on the footplate.
Safety valves lifting when the engine is not working hard or stopped, was always considered and is, a waste of water, coal and steam.
If your engine is working and requires coal and water at the same time, do that. Use your injectors at any time, to add water to the boiler and close your dampers, if steam pressure rapidly rising when coasting or stopped, but don't overfill the boiler. In real life, that can cause priming and of course less room for your steam to collect above the water level, reducing your reserves of steam.
Best.

[sidneyschwartz]

Great information, and I think I even understand it. Thanks so much!

[Broomwagon]

A must watch:

https://youtu.be/NHo860Q66Gw

On a separate note there was recently a programme covering the flying scotman - a recent full journey - think on the Severn valley line, the safety values blew off once. The fire man was a little embarassed having had the safety valves operate just once....but if you watch film of steam back in the day a lot of locos are running around with the valves blowing off.....I think we probably drive our locos to higher standards as I guess they're all rather precious to us rather than being just the daily workhorses they were.

When using trainsim my locos are pretty much the same, safety valves blowing a lot of time....largely because of CB's advice that the blower should in use at all times..unfortunately as CB intimated the loco physics aren't necessarily correct......though I tell myself it still looks authentic going on a lot of the youtube films I watch.

[Chicken Balti]

Hello broomwagon, towards the end of steam, some fireman realised they were going to be out of a job and understandably lost heart in the job. Filthy engines no longer cleaned, engine faults not considered by the home depot worth fixing now the cutters torch looming and low moral, all came together to form a 'can't care less anymore' attitude for 'some' fireman in the lower links hauling goods.
Some just filled the box to the saddle plate, shut the doors, blower on hard, dampers wide open and could not care less anymore if the safety valves were constantly lifting.
Very sad really.
Best.

[Broomwagon]

Ah never thought of that, indeed naturally a large body of the film we have of steam is towards its end....still when I'm running trainsim which most of the time I do as BR steam (not quite so many options to run grouping on TS), having the safety's going off is probably quite authentic for the time.

[Broomwagon]

P.S I don't suppose anyone knows whether the effect having the firebox door open or closed is simulated on TS......my feeling is it's not....on TS I 'think' it makes no difference to steaming.

[Chicken Balti]

Originally posted by broomwagon:

P.S I don't suppose anyone knows whether the effect having the firebox door open or closed is simulated on TS......my feeling is it's not....on TS I 'think' it makes no difference to steaming.

Hello, I believe it is on some Pro TS engines and certainly has a huge effect on steam generation in real life. The firebox doors are only fully shut once all the Hydro Carbons that produce thick black smoke are burnt away from the firebed coal. The fireman then uses 'Primary Air' coming through the open dampers to aid combustion and obtain maximum white hot 2800f heat energy from the coal.
With fresh coal added to the firebox, the fireman will only close the doors part way, to allow 'Secondary Air' to enter through the gap between the part closed doors. That secondary air mixes with the gases given off with combustion below the Brick Arch above the firebed and allows those gases to ignite and burn, so releasing even more energy from the coal to turn water into steam.
The fireman will watch his smoke colour coming from the exhaust, he will fire to that and be looking for a light grey/brown shade to that smoke, telling him his regulation of the firebox doors and dampers is correct or not as the case may be.
When the smoke clears, time to add more coal, if the engine is still working hard and requires it to generate more steam.
Best.

[Phase3]

A simmer called Cordell posted several ideal specs fore steam locos on RWA -
sample http://imgur.com/a/5z5jO But as ever CB's post describes everything so accurately!

[sidneyschwartz]

Love that video. Quite interesting stuff, and gives me a much better idea of when to do what. Also makes it abundently clear why you need a crew of at least two.

So what happens to the ashes as the loco is running?

[Chicken Balti]

Originally posted by sidney.schwartz:

Love that video. Quite interesting stuff, and gives me a much better idea of when to do what. Also makes it abundently clear why you need a crew of at least two.

So what happens to the ashes as the loco is running?

Hello sidney, the ashes fall through the grate into the ashpan underneath. The ashpan also contains the dampers placed at each end and higher than the base of the ashpan.
Some ashpans were fitted with opening hopper doors controlled by a locked lever to allow the ash to be emptied over the ash pit. Most engines required the fireman to rake out the ashpan through the open dampers into the ash pit.
It was and still is, common to 'wet the ashes' before removal to reduce the high levels of dust, not only bad for the person emptying the ashpan, but bad for the motion too. Dust is abrasive and not wanted in bearings, axle box's or coating slide bars.
Some engines were fitted with ashpan sprinkler pipe work controlled from the footplate to damp down the ash. Some engines were also fitted with 'Rocking Grates' operated by a lever in the cab, to aid ash and clinker removal possibly blocking the spaces between the fire bars.
It was normal practice on most engines to clear blocked grates by using 'Fire Irons' carried on the engine.
Best.