boiler pressure
- Thread starter Jayturf
- Start date
When climbing a long steep grade I like to feed the fire small amounts and very often to keep the fire hot. You also need to keep adding water via the injectors which tends to drop the fire temp as well. My aim is to keep the water level somewhere in the 2/3 to 3/4 full range. Often I find that the pressure will only be maintained at around where you started so it is necessary to always keep a good head of steam going so that you don't begin a climb from a low head of steam. If stopped you need to employ the blower (N key is on; shift N is off) to bring pressure up and keep a fire burning brightly. Probably not the complete answer but it usually works for me. And you can be really busy being fireman and driving the loco too!
Cheers
Russell.
the art of firing
When they describe firing a steam locomotive as an art it is a fairly accurate statement. In my experience firing (a SJ class B 4-6-0) you need to be thinking 5 to 15 min ahead of your current performance or location, especially if you are responsible for more than the exclusive operation of the boiler. You should also be able to understand what your engineer is potentially going need for an abnormal situation and be able to act accordingly. While some of this does not apply to trainz, the steam modeling is accurate enough to reflect the need to plan ahead. At this point I will admit to a tendency to rely on the AI fireman, in part due to a lack of information that I am used to having. It is difficult for me to judge the performance of a firebox in Trainz due in part to that lack of information, like feeling the heat and seeing and hearing the exhaust. For my part I accept the limitations of the program (I run 04), and will comment on my limited real world experience. As I said earlier planing ahead is esential, and even litle things can throw off careful planing. To climb a grade you should add watter and fuel some distance ahead of the grade (remember that whole art thing), and understand the efect each has on the boiler. If you already understand this or don't want read through my explination you can skip my explination below.
---Science content warning---
I was told that this is really some verry basic thermodynamics. It is the diference in tempeature (sometimes called 'delta-t' by the nerds) between the fire and the water (liquid or gas) that affects the generation of steam and consequently the presure. When you add something cold to something hot it cools down. Adding coal will cool the fire (as will opening the firebox doors), resulting in a decrease in the diference in temperatue. Reducing the draft on the fire (by stopping) will cool the fire as the cobustion slows, resulting in a decreaes in the diference in temperature. Adding water will cool the fluid in the boiler resulting in a decrease in the diference in temprature. A decrease in the diference in temperature will reduce the rate at which the steam is generated. Using the steam will also afect the generation of steam as you decrease the pressure and remove the energy from the boiler.
---End of Science content---
The key to firing a longer grade is to add consistantly at the same rate to your boiler and firebox. Just before any point at wich the engineer reduces the throtle is a good place to add extra fuel or water, this will also help you to manage the boiler pressure. It is important to be atl est somewhat familir with the line you are on, as this will aid you in your planing. In respect to errors in your planning, unexpected events can take upwards of thirty minutes to return your steam pressure to the desired amount.
Remember, just keep at it and have fun. I hope some of this helped.
When they describe firing a steam locomotive as an art it is a fairly accurate statement. In my experience firing (a SJ class B 4-6-0) you need to be thinking 5 to 15 min ahead of your current performance or location, especially if you are responsible for more than the exclusive operation of the boiler. You should also be able to understand what your engineer is potentially going need for an abnormal situation and be able to act accordingly. While some of this does not apply to trainz, the steam modeling is accurate enough to reflect the need to plan ahead. At this point I will admit to a tendency to rely on the AI fireman, in part due to a lack of information that I am used to having. It is difficult for me to judge the performance of a firebox in Trainz due in part to that lack of information, like feeling the heat and seeing and hearing the exhaust. For my part I accept the limitations of the program (I run 04), and will comment on my limited real world experience. As I said earlier planing ahead is esential, and even litle things can throw off careful planing. To climb a grade you should add watter and fuel some distance ahead of the grade (remember that whole art thing), and understand the efect each has on the boiler. If you already understand this or don't want read through my explination you can skip my explination below.
---Science content warning---
I was told that this is really some verry basic thermodynamics. It is the diference in tempeature (sometimes called 'delta-t' by the nerds) between the fire and the water (liquid or gas) that affects the generation of steam and consequently the presure. When you add something cold to something hot it cools down. Adding coal will cool the fire (as will opening the firebox doors), resulting in a decrease in the diference in temperatue. Reducing the draft on the fire (by stopping) will cool the fire as the cobustion slows, resulting in a decreaes in the diference in temperature. Adding water will cool the fluid in the boiler resulting in a decrease in the diference in temprature. A decrease in the diference in temperature will reduce the rate at which the steam is generated. Using the steam will also afect the generation of steam as you decrease the pressure and remove the energy from the boiler.
---End of Science content---
The key to firing a longer grade is to add consistantly at the same rate to your boiler and firebox. Just before any point at wich the engineer reduces the throtle is a good place to add extra fuel or water, this will also help you to manage the boiler pressure. It is important to be atl est somewhat familir with the line you are on, as this will aid you in your planing. In respect to errors in your planning, unexpected events can take upwards of thirty minutes to return your steam pressure to the desired amount.
Remember, just keep at it and have fun. I hope some of this helped.
Regarding what TSwenson has said I know the Victorian Railways here in Australia issued to all steam-engined crews a publication called a "Grades Book" (I think this was the correct title) that showed all the relevant grades on the lines they were working. This enabled those crews who were unfamiliar with the area to do the forward planning for the line ahead. Crews that worked the area regularly got to know when to make the adjustments to coal and water to prepare for what was coming.
A grades chart was probably more common than I know?
Cheers
Russell.
A grades chart was probably more common than I know?
Cheers
Russell.
Re the blower in trainz:
Blower is set using N key as mentioned but not as an on/off toggle. 1st step is 50% then in 10% increments to 100% so you have to hit N 6 times to set it at 100%. Works similarly shutting it down using shift N. Shame they don't have any indicator because there is no way to tell what the setting currently is unless you have a custom script that reads and displays it or a control device in the cab that can give some indication.
When running with less than 50% throttle - in Trainz - you don't get much draft from the exhaust and running on partial throttle for long will result in loss of pressure unless blower is turned on. When stopped you must have it on to build up pressure. In TC3 the steam physics was completely rewritten and TS9 uses the same new code so draft effect may be different for them.
On a long grade if you have trouble maintaning pressure (with a full throttle and adding coal at frequent intervals) you'll have to reduce the cutoff setting. This limits the amount of steam going into the cylinders and lets the boiler catch up. It also reduces the force produced and your speed will drop but this too helps reduce the load on the boiler - amount of steam it has to produce per unit time. For most steam locos there is a relationship between speed and cutoff setting at which the boiler can't keep up. Steam consumption per unit time is dependant on boiler pressure, cutoff setting and loco speed.
Of course this is based on steam e-specs that tend to be somewhat realistic for the loco you're driving. Locos in Trainz will run with many different setting in the epsecs and some are not that realistic like consuming very little steam even while driven hard.
Bob Pearson
Blower is set using N key as mentioned but not as an on/off toggle. 1st step is 50% then in 10% increments to 100% so you have to hit N 6 times to set it at 100%. Works similarly shutting it down using shift N. Shame they don't have any indicator because there is no way to tell what the setting currently is unless you have a custom script that reads and displays it or a control device in the cab that can give some indication.
When running with less than 50% throttle - in Trainz - you don't get much draft from the exhaust and running on partial throttle for long will result in loss of pressure unless blower is turned on. When stopped you must have it on to build up pressure. In TC3 the steam physics was completely rewritten and TS9 uses the same new code so draft effect may be different for them.
On a long grade if you have trouble maintaning pressure (with a full throttle and adding coal at frequent intervals) you'll have to reduce the cutoff setting. This limits the amount of steam going into the cylinders and lets the boiler catch up. It also reduces the force produced and your speed will drop but this too helps reduce the load on the boiler - amount of steam it has to produce per unit time. For most steam locos there is a relationship between speed and cutoff setting at which the boiler can't keep up. Steam consumption per unit time is dependant on boiler pressure, cutoff setting and loco speed.
Of course this is based on steam e-specs that tend to be somewhat realistic for the loco you're driving. Locos in Trainz will run with many different setting in the epsecs and some are not that realistic like consuming very little steam even while driven hard.
Bob Pearson
Is it a better idea to apply only a little bit of steam and lower the cutoff to increase/decrease speed as required? I do this and it works, but I'm not sure how it happens (or used to happen) in real life.
Cheerio,
Nicholas.
Hi Nicholas,
Bob's advice above is pretty good, read it carefully and practice.
On real steam locomotives, at least the ones I worked on, the blower is used to supplement the natural draft on the fire when not heavy steaming. When the regulator is opened fully, you could turn the blower off, then just crack it a little.
You always needed the blower on when the regulator is closed, and that is good co-operation between both crew members, and a good knowledge of the track ahead. The fireman would know when the driver is going to close the regulator, and adjust his fire accordingly.
When running a steam locomotive, usual practice is to have the regulator fully open, and work on the cutoff to regulate speed.
There were times when you needed to run with less than a full regulator, but you needed to keep the cutoff out enough to maintain a sufficient draft on the fire. There are so many variables, but a cutoff of 12 inches kept a good draft on the fire.
There are several types of injectors used on steam locomotives, but they mostly work the same. Look at it this way, you have a boiler with maybe six hundred or more gallons of hot water, and in the space between the water line and the top of the boiler steam is produced by heat transfer from the tubes, flues, combustion chamber and the firebox. Now, say you have 200lbs/sqin in the boiler. You have a tender with water. Some of that water needs to be introduced into the boiler to keep it at a working level. The pressure needed to get the water to flow into the boiler through the clack valves needs to be greater than the pressure in the boiler. This is where the injector comes in. By increasing the speed of the water through the use of cones in the injector which increases the pressure of the water above that in the boiler, the clack valve opens, and allows the water to go into the boiler. When you go into cab mode on a steam locomotive, you will see the injector steam valve in the two o'clock position. this is the normal position when the injector is shut off. When the injector is opened, in real steam locomotives, two or three turns, the handle is always left pointing at six o'clock. This allows the driver, by merely glancing across at the firemans injector, to see whether the injector is either open or closed. On a real steam locomotive, you have to open a water valve first.
The main type of injectors used are either lifting, or non-lifting. This means that the water is either lifted, in the case of a gresham injector, or non-lifted, in the case of the nathan injector, which means the water from the tender flows by gravity to the injector, underneath the cab floor. There are many different types, some locos had feed water heaters.
I hope this helps Nicholas.
Pete :wave:
It is rather overwhelming, and very informative. I appreciate the effort spent on it, thank you. There's an increase in mileage for the same load of coal (I have a "low fuel" session on one of my routes) which is great. I am not constantly on the forums, so pardon me for the delay. Thanks again for the advice. 
Cheerio,
Nicholas.
Cheerio,
Nicholas.