I've avoided responding to this thread for as long as I could hold out. I'll reluctantly jump in here as I see this concept of a 'thick' fire = more heat as opposed to a thin fire = less heat. Hogwash!
gregcthe fire can have different depths, producing different # of BTUs, generating different amounts of steam (lb/sec)
Probably no where in the industrial world is the marriage of 'man and machine' more pronounced than in the operation of a steam locomotive.
The variables are broad. Various coals give up their volatiles at different rates. The ash, sulpher, fixed carbon and moisture content will be a big determining factor in the ability to carry a thin fire or not. Other impurities in the coal will be another factor in weather or not the fireman will be able to perform his duties efficiently. It can be the difference between having a run that is a 'stroll in the park' or a constant battle with clinkers, grate shaking, plugges flues, plugged netting in the smokebox and finally, how much of the volitale gases can be given up in the firebox and combustion chamber before being carried out the stack.
The variety of coal will be an indication to the fireman what type of fire he will want to carry. Most will bank a fire toward the back corners and along the sides of the firebox. Some coals burn best with a level fire and yet others like a flat bed and maybe a little thin in the center.
Locomotive condition is another variable. Leaking flues and cracked staybolts were something to contend with along with the aforementioned bad coal. A regular fireman on a regular run pretty much knew what kind of coal his road provided but there were still variables.
I have never once witnessed a situation where the engineer tells the fireman to lower his boiler pressure because he wants to slow the train down. This borders on ridiculous. Likewise, I want to go faster, shovel more coal.
In the days when I was firing I kept the needle within a few pounds of 200 psig. while on the road. The engineer deserved to have the full capability of the locomotive at his disposal and it was the fireman's duty to deliver that.
I worked with about five different former B&O engineers and each one had 'his' style. One I recall had about the easiest-going demeanor and his running of the engine followed suit. Very easy going and 'low-impact' hardly working the engine at all. Another was a bit of a 'throttle jockey' and I had to work a little harder. His style was to nearly constantly work the throttle, automatic and reverser always seemingly trying to find the 'sweet spot' but never really be satisfied.
The main driver of successful firing is anticipation and cooperation. The fireman has to know the territory in order to have both the fire trimmed and the water level where he needs it (you'll carry a full glass going uphill but you'd better know when you are about ready to crest and all your water runs to the front of the boiler, leaving a pretty thin margin for keeping the crown sheet covered!) also water level can be a convenient way to bring pressure down to avoid 'popping off'.
In the steam days most roads were very concerned with heavy firing and unnecessary smoke. Charts were kept on fireman's performance and it wasn't unusual for the road foreman to give a little 'pep talk' to the under performers.
That's enough for now...
Ed
In your thinking. If you dump the fire the locomotive will not move. Wrong. As long as there is steam in the boiler, you can start and move the locomotive. I read an article years ago where they put a K4s on the test plant. They tested different firing methods. One was a banked fire the other a flat bed. Lines West fireman liked running banked fires. Coal was piled up on the back of the firebox. Then raked forward as needed to cover the grates. Altoona men used level firing and liked thin beds. There was no discernable difference in steam generation. Banked firing had unburned coal when dumped while level fire consumed more coal during the testing.
While steam generation is a factor in locomotive performance. Without an ample boiler the locomotive will probably never leave the shop.
The fire is one small cog in the whole machine.
wjstixIf the throttle is fully open, all the available steam is going to the cylinders
all the available steam for that amount of fire. the fire can have different depths, producing different # of BTUs, generating different amounts of steam (lb/sec)
wjstixTheoretically, if you add more fuel to increase the boiler pressure
boiler pressure does not indicate how much steam is produce by the boiler. it indicates when more or less steam is being consumed by the cylinder than produced by the boiler. it rises when less is consumed and falls when more is consumed
adding more fuel increases steam production (lb/sec). even a slight increase in boiler pressure (~2 psi) results in more steam flow (lb/sec) into the cylinders, higher cylinder density/pressure, tractive effort, acceleration and speed.
more steam is consumed by the cylinders as speed increases, if speed doubles, there are twice as many cylinder cycles and twice as many cylinder volumes to fill.
a higher speed will consume steam at the new rate and boiler pressure will again remain constant
same boiler pressure as before, but higher steam production, consumption and speed
wjstixThe throttles regulates the amount of power - steam - that goes to the cylinders to turn the drive wheels.
it could be used that way; probably is on a switch engine in a yard running at much less than max boiler pressure. but the table below shows full throttle at 9, 20, 30 and 40 mph.
running with anything less than full throttle prevents all the steam produced by the boiler from entering the cylinders. the excess steam in the boiler builds pressure and is wasted thru the pop-off valves.
a throttle is absolutely necessary to start a locomotive, to limit the flow of steam into the cylinders when the wheels are barely turning. the throttle is just "cracked" to start the loco
greg - Philadelphia & Reading / Reading
dehusman gregc the fireman is the "gas pedal". The fireman is the fuel pump. He make sure there is an adequate supply of steam to run the steam engine. If he supplies an inadequate amount of steam the engine will not be able to make speed. If he supplies too much steam it will be wasted.
gregc the fireman is the "gas pedal".
The fireman is the fuel pump. He make sure there is an adequate supply of steam to run the steam engine. If he supplies an inadequate amount of steam the engine will not be able to make speed. If he supplies too much steam it will be wasted.
i agree -- that's a better description
but if he builds up the fire, when the train is running at a steady speed and the boiler pressure is not maxed out, the boiler pressure will rise and more steam will increase the speed of the train.
2729
If the throttle is fully open, all the available steam is going to the cylinders, so the engine is going as fast as it can. Theoretically, if you add more fuel to increase the boiler pressure up to the point that the safeties blow, then yes perhaps the engine will go a little bit faster.
But I think your question may point out that you're not understanding what the throttle is. The throttles regulates the amount of power - steam - that goes to the cylinders to turn the drive wheels. The more steam passed to the cylinders, the faster the engine goes. If, as in your original question, the throttle is fully open and the engine is going 20 MPH, increasing the boiler pressure by adding all the fuel you can will only increase the speed a few miles per hour. But again, that's unrealistic. A steam engine going 20 MPH is only going to have the throttle partially open, half or less.
gregcthe fireman is the "gas pedal".
The fireman can have the engine producing enough steam to lift the pop valves and the train can be standing still. The engine isn't going anyplace until the engineer opens the throttle.
Dave H. Painted side goes up. My website : wnbranch.com
wrench567I don't understand what you're stuck on?
that you and others seem to believe the boiler is producing the maximum amount of steam at all times or only as much steam as needed.
of course you can have the boiler producing more steam than is required with the pop-off values wasting the unused steam and you can use the throttle to control speed.
The boiler pressure is not a measure of how much steam the boiler is producing. The boiler pressure will remain constant if the boiler is producing the same amount of steam (lbs) as being consumed by the cylinders.
why not build the fire only as strong as needed, some bed thickness, to maintain the boiler pressure maybe 5,10 PSI below max boiler pressure when operating at the desired speed. add more coal when it goes below that, stop adding coal when it starts to rise above it
to increase speed, the fire needs to be strengthened to accelerate. After increasing speed,
OvermodA good fireman will estimate the additional fuel the engine will need at the new higher speed
the stength of the fire, bed thickness, can vary to change the amount of steam produced by the boiler as needed.
the fireman is the "gas pedal". on an oil fired steam engine, it's a valve that can be opened more/less to control the strength of the fire and the amount of steam produced
2642
I don't understand what you're stuck on? The boiler was designed to produce more steam than it could use in a given time. When you admit more steam into the cylinders, the boiler is still making steam. The volume of the steam dome and super heater will have enough reserved for quite a distance. All the while the boiler is still evaporating water. The fire is still hot. The crown sheet doesn't instantly cool.
gregc PM Railfan "..... what determines "how fast the locomtive will go"? my mistake. should be how does a steam locomotive increase speed?
PM Railfan "..... what determines "how fast the locomtive will go"?
my mistake. should be
how does a steam locomotive increase speed?
Gotcha. In that case it goes back to what ive already been saying.....
Ya turn the knob on the transformer, the light gets brighter on the loco, and the train goes faster. And like that.
I forgot we were modellers!
PMR
i don't understand why Mollar Charts are needed to understand that coal/oil provides the energy that propels a train.
as the train speed increases, the train resistance increases, requiring the (MEP) cylinder pressure to increase, requiring more steam. (assuming optimal operation)
while various controls allow more steam into the cylinder, the amount of steam can only be what the boiler produces. Any excess steam produced by the boiler is wasted thru the pop-off valves. The fire is only as strong as needed to maintain boiler pressure and not waste steam/water/fuel.
100 lb of coal can burn per hour per sq.ft of grate area. more/less depending on depth. A 100 sq.ft grate can burn 10,000 lb/hr or 166 lb/min. The density of coal is 52 lb/cu.ft. At this rate, the fireman needs to shovel 3+ cu.ft/min. (it's not like a charcoal file the lasts for hours)
~1520 BTU are needed to produce 1 lb of steam. There are ~11000 BTU per lb of coal. Burning 10,000 lb/hr of coal can produce ~72000 lb/hr steam
these are ballpark numbers
working from train resistance, tractive effort, cylinder pressure, steam density and mass (lb), a 5000T train traveling 20 mph requires ~7000 BTU/sec and 38 lb/min coal. A 30 mph train requires ~13000 BTU/sec and ~72 lb/min coal. A 50 mph train requires ~40000 BTU/sec and ~219 lb/min coal.
conservation of energy
While cutoff can be adjusted to change the admission of steam, as well as use is optimally, steam production needs to increase. I don't see how that happens without increasing the rate of coal being added to the fire.
I apologize, but I can no longer post from a phone at all, thanks to Kalmbach incompetence in advertising forcing page resets and very, very, very slow typing throughput (or clever shadowbanning, perhaps).
The 'succinct' answer is that changes in steam admission are the only thing that makes the locomotive go 'faster'. All the fire does... ALL the fire does... is to put heat energy into the steam so it can exert more pressure over a long expansion (and incidentally give up some of the heat/pressure as work as it does). The steam does the work, and that is what dhusman meant when he called it the 'fuel' of the actual engine of the locomotive.
The situation is of course much more complex than that, but you'd need to study about the physics of steam, understand why Mollier charts are valuable, etc. to see just how much power can be developed (as pressure) from a comparatively small charge of initially high-pressure, high-temperature steam vs. admitting a 'whole cylinder full' and then letting it blow to exhaust, as in an engine with low or no fixed cutoff operated in full gear. You have already noted that a very small actual mass flow can have very long expansion and still produce smooth 'enough' torque above a certain (and relatively low) cyclic rpm to give effective TE at speed. For very high speed, even with large diameter drivers, the effective duration of admission is measured in milliseconds, and it becomes important to "push" an adequate mass of steam into the cylinder in that time, but there is then more time for 'long expansion' and hence both lower pressure and lower mass to be exhausted when the cylinder opens to exhaust (the thing that most people looking at higher pressure as the 'answer' to Moar Power often don't think about...)
The 'automatic action' is something that an extraordinary amount of (relatively unsung) design, proportioning, and construction goes into facilitating. Note that to go from 20 to 30mph requires more admission steam mass flow. But it is NOT proportional in lb. of steam as "33% more" than at 20mph, unless the engine is well over the peak of the torque curve or has lousy port and passage flow, etc.
It's sort of a honeytrap for armchair thermodynamicists to concentrate on front-end arrangements that provide the greatest possible road speed -- for bragging-right speed records, for example, with engines that will remain nameless. Something more important, though, is arranging the front end for best overall fuel efficiency (at least in a world where fuel was an expensive cost and water was perceived as relatively cheap and fungible) and fuel once stoked would burn 'as it wanted' without the ability to "decrease the fire" as on an oil-burning engine, or wind a chain-grate backward as on the N&W M2 Automatics or the TE-1. In the engine's normal operating range, and 20 to 30mph is certainly in that range for most locomotive designs, the 'idea' is to have the draft change by just the amount that produces the additional heat release, then heat uptake, then steam generation to sustain the higher mass flow.
Naturally, at that firing rate, you might have to stoke more frequently or using a different pattern. But that is done, as mentioned, with reference directly to boiler pressure and water level, which makes it somewhat easier for a fireman.
A 'correct' fire doesn't look at all like something in a charcoal grill, and anyone using that as an analogy has almost certainly never seen an actual locomotive fire in an engine running under load. There is usually more fuel in there than required for instantaneous power change, so that you might not need "extra" firing right away when the added draft brightens the fire still further. Fred Westing interestingly observed that some PRR engines used in commuter service, if started with a properly-built fire, would run for as much as 37 miles without any stoking (nothing was said about trimming).
Now, there's no guarantee that 'automatic action' applies to an engine in poor condition, or burning strange fuel. It is quite possible for an engine to lose the ability to 'keep up' with steam demand, and not infrequently this results in what the English call a 'blow up', where the engine has to be stopped, the blower put on, and the fire brought to effective brightness and mass flow of combustion gas to restore steam pressure for a boilerful of water.
One of the potential complications that you shouldn't let snare you when trying to understand this is that the steam needed to accelerate the train from 20 to 30mph might be easily sourced from the boiler water and existing fire, and when the reverse is adjusted to hold at steady speed the steam demand drops down to a level that existing conditions could maintain. This is less weird if you think about how a fireless cooker could accelerate a train or cut of cars, with no "fire" at all...
Can somebody like Ed find and post the graph from Wardale's Red Devil book that shows actual wheelrim torque from a 2-cylinder DA over one full driver revolution, at 15-degree increments? I think that alone would give him tremendous insight into what is happening in each of the four strokes occurring in one revolution, and why they overlap without crippling torque peaks much of the time.
The 'succinct' answer is that changes in steam admission are the only thing that makes the locomotive go 'faster'.
OvermodSheesh To 'go faster' you will lengthen the cutoff to increase the mass flow per stroke. This will draw additional steam from the boiler On the other hand the additional mass flow of steam means additional mass flow in the exhaust... hence more draft, hence a brighter fire. At some point, probably before balancing at 30mph, you will resume the 'firing early and often' that you should have been attending to at 20mph. A good fireman will estimate the additional fuel the engine will need at the new higher speed on the relevant part of the railroad... and fire and trim accordingly.
To 'go faster' you will lengthen the cutoff to increase the mass flow per stroke. This will draw additional steam from the boiler
On the other hand the additional mass flow of steam means additional mass flow in the exhaust... hence more draft, hence a brighter fire.
At some point, probably before balancing at 30mph, you will resume the 'firing early and often' that you should have been attending to at 20mph. A good fireman will estimate the additional fuel the engine will need at the new higher speed on the relevant part of the railroad... and fire and trim accordingly.
I apologize for not recognizing this earlier (from page 1)
i hadn't considered the increased draft on the fire and temporary increase in BTUs
but "additional fuel the engine will need at the new higher speed" implies that the fireman increases the rate of coal being added to the fire
2388
OvermodIncidentally, here is a question for you: how do we 'conventionally' determine the P in the PLAN formula, and what is one of the common reasons why we do that?
i had never heard of PLAN and had to find a description which says the P is the mean effective pressure that results from early cutoff and expansion.
but the MEP is based of the initial pressure while the intake valve is open. it's not obvious (to me) what that pressure is
one answer is it depends on the amount of steam (lb) in the cylinder and the volume of the cylinder at cutoff which determines the density and pressure (see steam table)
i've been trying to figure out how to estimate amount of steam that enters the cylinder before cutoff.
if each cylinder were at 50% cutoff, all the steam produced by the boiler passing thru the throttle can enter one cylinder or the other because when one cylinder reaches cutoff the other cylinder is just starting its cycle
at 50% cutoff, my understanding is MEP is 87% of the initial pressure
whatever steam produced by the boiler that doesn't enter the cylinders will build up in the boiler, increasing its pressure and possibly vented thru the pop-off valve. If boiler pressure builds, the steam flow (lb/s) will increase, along with density/pressure and tractive effort. there will be some equilibrium point at some speed where all the steam produced by the boiled enters the cylinders
but at less than 50% cutoff, both intake valve will be partially closed some period of time and steam pressure is likely to build during that brief period.
I believe the result in that the same amount of steam that enters the cylinders at 50% enters when at 20% cutoff. half of what is produced by the boiler. since the volume is 40% of what it was at 50% cutoff, the density is 2.5 time higher along with pressure.
MEP for 20% cutoff is 68%. the net difference in cylinder pressure is 1.7 (2.5 * .68) which is why cutoff makes such a big difference.
2329
selectorYes, coal consumption varies, or ought to, with changes in boiler work.
thank you
Yes, coal consumption varies, or ought to, with changes in boiler work. A seasoned stoker, who knew the route, would know when to start pouring the fuel to the firebox, and then when to desist. All the while, the boiler is being drawn down, sometimes harder, sometimes less, but the water injected/fed was always cooler than what was emitting from the throttle at the front end.
The HP curve of a steamer shows it rising as speed increases, but only up to a point. By the time the pistons, on a typical steamer, are reciprocating at about 3.5 - 4 times each second, the highest possible horsepower is being put to the piston. This also coincides with the shortest cutoff. Rapid, short, pulses of full-throttle steam are being puffed through the inlets and then expelled via the outlet ports, which keep the steamer at speed.
OvermodWill you stop asking the same question over and over no matter how many people answer it for you, and bringing up more irrelevant details and numbers you don't understand the meaning of?
if you can provide a succinct answer?
a basic law of physics is conservation of energy, that the source of energy is the coal. a constant amount of energy is needed to overcome train resistance to maintain speed. a higher amount of energy is needed to accelerate and then maintain a higher speed because train resistance is greater. just as more gas is needed in a car (your gas mileage drop when going faster)
a common answer is that the fire is maintained to maintain boiler pressure. no one has suggested that the rate of coal consumption varies in order to maintain that pressure. Somehow adjusting throttle or cutoff increases the speed while the boiler pressure remains constant.
Overmod of course max speed depends on various things. but i believe the simplest answer is the speed where the train resistance equals the max tractive effort above which results in slip.
of course max speed depends on various things. but i believe the simplest answer is the speed where the train resistance equals the max tractive effort above which results in slip.
Will you stop asking the same question over and over no matter how many people answer it for you, and bringing up more irrelevant details and numbers you don't understand the meaning of?
That isn't even wack enough to be wrong, as a moment's reflection on your part ought to make clear. Maximum speed is the speed at which train resistance (rising with speed) exactly balances developed drawbar tractive effort (falling with speed). It can also be thought of as the point that the locomotive no longer develops enough power to accelerate the train under the instantaneous running conditions.
There is such a thing as 'high-speed slipping', and under certain conditions it is indeed a limitation on achievable top speed. One canonical example was described by E.T.Harley (who knew his duplexes!) in his book on the Q2s -- he was on a train pulled by a T1 in bad weather and poor rail conditions, and there came a point where no further power could be transmitted through the driver contact patches on at least one of the engines (probably the forward one) and it would momentarily slip. This would of course throw the load onto the other one, the engine would slow down, and the slipping engine would 'catch its feet' -- the result being a repeated rhythmic surge, damped by the mass of the tender, not progressing to wild spinning drivers as in the general FRN conception of a T1 slip, but not permitting any further acceleration of the consist.
But notice that this isn't like a tractor pull, where the wheels start slipping when the load is too great. Even for the T1, the much more likely consequence of an overload, even at starting, would be as clearly described in the C&O road testing described by Dave Stephenson (feltonhill here) -- the engine simply stalls, refuses to accelerate, or bogs down.
And you fix that (to the extent you can) by adjusting the REVERSE, to allow more admission. To the extent you do anything with or to the boiler, you control fire and feedwater to keep the nominal boiler pressure as close to the desired pressure as careful experience and knowledge permit.
I will happily get into a discussion of how admitted steam flow translates into internal-combustion engine terms, since nobody else seems to understand that competently, either. But it doesn't apply in any real sense that would give you better understanding of the question you keep trying to ask.
At some point we might have to take up a critical difference between 'gas' engines and steam engines, which is the loss via physical phase change to liquid during the stroke duration (and then the losses involved in re-expansion to vapor when you don't want it, during release). This is not just the usual-suspects wall condensation; it involves what is called 'nucleate condensation' throughout the expanding steam mass as work is extracted via piston thrust, and nucleate condensation is THE principal reason superheating, and not steam jacketing or better external insulation, has such a tremendous effect on locomotive performance.
Actual maximum high speed depends on a number of things like admission time per stroke, shock in the intake tract or flow instabilities near valve unshrouding, and balancing effectiveness. I can assure you that the reason a British 9F can reach 90mph has nothing whatsoever to do with any Reading I-class locomotive, and comparatively little to do with Reading locomotives built using components from I-class locomotives.
Incidentally, here is a question for you: how do we 'conventionally' determine the P in the PLAN formula, and what is one of the common reasons why we do that?
May be helpful to remember that a steam engine is an external combustion engine (unlike an automobile motor, which is internal combustion). The coal, oil or wood burning in the firebox creates heated air that passes through the boiler tubes to the smokebox, where it is then vented out the stack. The fire isn't in the boiler.
When a steam locomotive completed it's run, the fire would be dumped in the ashpit on the way to the roundhouse. Even with no fire, there was sufficient steam to run onto the turntable and into the roundhouse stall.
dehusmanThe fuel of a steam engine is steam, not coal.
that's simply not true
2206
gregcit probably takes just as long for a fire to burn down by not adding coal as it does to build up when adding coal
Evidently you've never used a charcoal grill. If you put fuel on the fire it catches fire in a matter of minutes and burns for a long time.
gregcwhat do you think determines the tractive force?
As other people have stated, wheel diameter, cyclinder size, steam pressure, etc., etc.
If the question is how does a locomotive change pulling power while running? Adjusting the throttle and cut off. Very simple.
All changing the fire does is keep an adequate supply of steam based on it's usage, in economics it would be called a "trailing indicator".
You started off this discussion by articifially constraining the the controls an engineer uses to operate the engine (throttle wide open and cut off at max) and then asked how do you control the engine without using the controls.
Get a picture of a really basic locomotive and look at the controls the engineer uses that are connected to the running gear. The answer to you question is in THOSE controls and in the devices attached to those controls.
You could do exactly the same with a car. How does a driver change speed and power in a car? Look at what controls the driver has available. The gas pedal and the gear shift.
The fire and the steam pressure in the boiler may have an effect, but they are not a CONTROL. The fuel of a steam engine is steam, not coal. The boiler's job is to provide an adequate supply a fuel. It takes a relatively long time to change the pressure in the boiler and adjust the fire. That is not a CONTROL.
You appear to be trying to figure out how to run an engine by adjusting the pressure in the boiler rather that by adjusting the pressure in the cyclinders.
PM Railfan"..... what determines "how fast the locomtive will go"?
happen to look at some results that suggest a theoretical answer to this question.
i've been working with values for the Reading I-10 for which i have data for.
the following shows that max Tractive Effort (TE) is 71048 lb for an adhesive weight of 284190 lb. That max boiler pressure of 220 psi in a 27" cylinder is 224667 lb, easily exceeding the max TE. The train resistance roughly equals the max TE at 55 mph for a 5000T train
284190 adhesive wt (lb) 71048 max TE 220 Blr PSI 27 cylDia (in) 573 cylArea 224667 max cylPsi 5000 tonnage 55 mph 71794 res
of course, there are mechanical and efficiency limit that i don't understand that prevent such a locomotive from reaching much higher speed (e.g. 100), but i believe these values are in line with what the locomotive was designed for
why am i doing this?
because i'm trying to understand how a steam engine works and the nuances of it's operation. it would be great to get first hand experience from an operator.
2160
wrench567Wheel diameter, size and stroke of the cylinders, amount of steam getting through the ports, weight of train, gradient of track and courage of the crew.
i've considered all of the above, including grate area, to determine the flow (lb/sec) of steam entering the cylinder to determine the density of steam in the cylinder and its pressure
here are some value from the other thread on Bershire water consumption
25.0 mph 4.1 cps 30401.1 te 37.0 cylPsi 9.7 cylCuFt 78.4 cuFtPsec 6.4 lbPsec 23191.0 lbPhr 183480.0 lb tender 7.9 hr 197.8 mi
that ~150 lb coal per sq.ft of grate area is about the max. that there are ~11000 BTU/lb coal
but is any of that needed to understand that more energy, fuel (coal/oil) is needed to increase the power (tractive force) to overcome train resistance and gravity due to grade, to accelerate and maintain the speed of a train.
no one has a problem understanding the same for a car, that more gas is needed to go faster or up a hill
2110
gregc how quickly does a 5000 T train need to change speed. building speed or using brakes requires anticipation
how quickly does a 5000 T train need to change speed. building speed or using brakes requires anticipation
Ya know, thats a question that can again, can have a boxcar load of different answers. So, I am just gonna tell ya your gonna have to get some seat time and see for yourself..... just what it takes.
Best answer there is - hands on. But dont feel bad, everyone here needs some, including myself!
"..... what determines "how fast the locomtive will go"?
I dont know what rule people use today but, todays rule didnt exist back then. The rule of thumb for all time is this....
"1 mile an hour for every inch of driver size plus 10 miles an hour."
Loco with 53" drivers (would be a freight loco) could go 60mph. 70mph tops if your having a winning lotto ticket kinda day on the railroad. Anything faster......
You owe them a million dollars!
Wheel diameter, size and stroke of the cylinders, amount of steam getting through the ports, weight of train, gradient of track and courage of the crew.
The PRR T1 and K4s were known to go better than 100 mph at times. The N&W J was known to push 100 even with the smaller drivers.
By the 19 teens, locomotive development was to the point where they could design for specific jobs. There wasn't really a general purpose steam locomotive.
Pete.
wrench567Remember that steam is a gas. It will continue to build pressure until the safeties lift.
of course. what do you think i'm missing?
what determines "how fast the locomtive will go"?
gregc wrench567 The steam will stay in the steam dome until either the safeties lift or the throttle is opened again. what about the steam that continues to be generated by the fire immediately after the throttle is "almost closed"? and what determines "how fast the locomotive will go"?
wrench567 The steam will stay in the steam dome until either the safeties lift or the throttle is opened again.
what about the steam that continues to be generated by the fire immediately after the throttle is "almost closed"?
and what determines "how fast the locomotive will go"?
Remember that steam is a gas. It will continue to build pressure until the safeties lift.
PM RailfanYa gotta know adding coal to the fire and changing the bed thickness isnt instant steam production.
and i'm not suggesting that the throttle isn't closed or brakes not used on a switching loco in a yard making frequent stops/reversals
i am suggesting what it takes to run a steam engine and run it efficiently
but consider how quickly the strength of a fire on a oil powered steam locomotive can change