Steam & Excursion > Another Take on Loud or not so Loud Steam Locos

I've been watching video of United Kingdom passenger steam locos, some recorded running at very high speed. I get the impression that they are nowhere near as loud as steam locos in the U.S. Is this because they weren't designed to haul heavy trains or trains on steep grades relative to the USA?  Are there other factors, or is my imagination running at very high speed?

Victor A. Baird
http://www.erstwhilepublications.com

 



Edited 1 time(s). Last edit at 02/23/21 17:46 by wabash2800.

You're RIGHT, on ALL counts...
Their traffic loads are nowhere near what we haul...
their coal fired engines are all hand-fired...virtually no 
mechanical stokers.

And very light trains and no steep grades ... all combine to make 
for easy trains.  Also, they used many engines with 3, or more cylinders
in non-articulated frames....all of which contributes to softter exhausts.

Most of the time, on American rails, the loudness of the exhsust is entirely 
dependent on the mass ( weight)  being dragged behind the tender's coupler.

​W.

 



Edited 1 time(s). Last edit at 02/23/21 19:58 by wcamp1472.

Wes,

Always fascinating to read your details on steam locomotives.

I’ve read several of your posts that discuss how the locomotive needs a load to be efficient, burn clean, all sorts of benefits. Since a 200-car freight assignment is unlikely, can you describe the similarities or differences in having a diesel or two in dynamic braking as a replacement? Is that an apples to apples, apples to oranges, or apples to onions comparison? I know it’s been done, just wondering if it reaps the same benefits. Also, does it matter that there are lower limits of the speed at which dynamic braking is effective?

wcamp1472 Wrote:
-------------------------------------------------------
> You're RIGHT, on ALL counts...
> Their traffic loads are nowhere near what we
> haul...
> their coal fired engines are all
> hand-fired...virtually no 
> mechanical stokers.
>
> And very light trains and no steep grades ... all
> combine to make 
> for easy trains.  Also, they used many engines
> with 3, or more cylinders
> in non-articulated frames....all of which
> contributes to softter exhausts.
>
> Most of the time, on American rails, the loudness
> of the exhsust is entirely 
> dependent on the mass ( weight)  being dragged
> behind the tender's coupler.
>
> ​W.
>
>  

Posted from iPhone

Jared Hamilton
Scott Depot, WV

I just had to chime in on this one... Wes, I very much admire your knowledge of steam, but here I'm afraid you are very wrong. No steep lines? We have some of the steepest in the world, and many were exploited with steam for a long time. Lighter trains mean quieter engines? Why would that be? Engines are matched to their trains, which has nothing to do with the exhaust noise level. And why should 3- or 4-cylinder simple expansion engines be quieter? If you had ever seen and heard a pair of Belgian State Railways Type 36 2-10-0s (4-cylinder simple expansion), or German BR 44s (also 2-10-0, 3-cylinder simple) slogging up a 2% grade with a heavy coal train, you'd speak differently.

And what does hand-firing have to do with it, if I may ask? Many of our hand-fired engines, by the way, would have been equipped with a stoker in the US, but given the differences in labor and fuel costs, weren't (as you know, stokers are less fuel-efficient than firing by hand).

One of the things that could make a difference is -again because of the considerably higher fuel cost in Europe- a more widespread use of more refined, more efficient -hence quieter- exhaust systems (Flamme, Legein, Kylchap, Giesl, etc.). Or the sound level of old recordings... And finally, museum and excursion trains are rarely worked to their limits and cannot be used for comparison - just look at 4014.

Cheers! 

Jared poses a good question

I am paraphrasing his question, for clarity :
"What are the differences between electric "resistance braking' and
rolling resistance of a string of freight cars?"

Diesel electric locomotives are easy to rig-up to a fixed electrical resistance ( heat) grid.
Commonly called a 'load bank', or 'load-cell"

The output of the engine-powered generator is fed to an array of air-cooled iron ribbons
that exceeds the current capabilities of the crankshaft-generator combo to 'burn-out'  the
loading-grid.  You simply add enough grids to handle the heat generated.
 
During testing, you use electric meters to measure the volts & amps fed to the grid.  
The combined current measurements ( Volts times  Amps) gives you the
"power" generated, in Watts.

It is "magnetic braking" that retards the crankshaft.  
There is no "mechanical" braking force, like brake shoes 
against wheel treads.  Electrical braking occurs when spinnning a copper
coil inside an applied magnetic field.  

Diesel electric locomotives apply a dense magnetic field around the spinning
armature, driven by the wheels rolling on the rails.  You simply send a strong current 
into the ( stationary) field windings of the motor attached to the wheels, and the spinning
copper coil can move copper atoms to flow, if attached to a closed loop --- up to the heat grids.

The flowing atoms form a current in the loop.  Niagara Falls spins turbines connected
to electrical generators that produce immense amounts of current flows -- cities and towns
on the 'grid' provide the 'load' .

With diesel electric locomotives in braking mode, the grid electrical resistance is a fixed amount
of iron ribbons that get red hot and are air cooled.  They typically can handle 2000 hp to 3000hp,
( classic electrical Watts is defined as 747 Watts for one HP,  I think that today's diesel engineering
calculators round that figure down to 700 Watts)

NOW, the electrical power, in WATTS, increases as the square of the speed of the locomotive...
the grid is of fixed resistance... it can only handle maximum current flows from the axle (generators) 
up to about 25 mph....above the maximum current-speeds, the braking  field is automatically
reduced to limit current flows to the red-hot grids.  The total braking effort, in HP, is limited 
to the rated HP of the grids.

So, you would want to use more than one unit in braking, to 'hold-down' a modern,
high-power steam locomotive.

Pulling rolling freight cars provides a steady drag behind the tender.  As long as it's on
level, tangent track.  If the angle of the track grade changes, then either the weight
being pulled increases, if up-hill.  Or, if the loco is lower than the train ( down-hill) the train
shoves into the tender and engine, increasing speeds, until the next sharp curve...

Hopefully, the engineer regulates the train air brakes and engine  track speeds to 
maintain control of train speeds.

"Run-aways" occur when train wheel speeds and masses exceed the capability of the air brakes to 
slow the train down.  

So...steamers are designed to be drafted and fired at a maximum rate for hours on-end.
That way freight get moved, and money gets made by hauling freight --- the more freight hauled,
the more money is made.  It's expensive hauling freight, so the more you can CUT expenses,
the more money you keep.

So, in braking types, if a couple of dismals in braking mode is 'apples', then
rolling freight cars is 'oranges'.   The closest to the 'designed' weights being hauled,
is a decent amount of loaded freight cars --- Berks and Northerns liked 80 to 90 freight cars 
across rolling flat-lands of North America. 

But, operating officers are reluctant to risk regular freight trains to steam locos, in today's 
rapidly changing RR environment.  Especially with use of DPUs buried halfway back in the trains.

Sorry for the wandering 'power' and 'braking' attempts at simplifying sophisticated concepts of
electro-magnetic fields and motors.  

Edison refused to understand the very sophisticated 3-phase electricity, invented by Tesla...
Edison went to his grave championing DC as the only way to make electricity..
Recently, variable-frequency 3-phase electricity gave us 3rd Generation rail locomotives.
My favorite to watch in action... but, they're very fuel hungry machines..

I also am mesmerized by aerial con-trails across the clear blue skies....
it reminds me of Parsons' invention of the steam turbine, in the late 1800s
And how that grew into today's turbo-fan aircraft engines..

They all trace their trace their lineage to Sadi Carnot, a young French mathematician,
who was  the first to apply mathematics to predicting heat events inside cylinders.
 Carnot (car-NO)  was commissioned by his father to solve pressure problems for his
cannon factory and for Napoleon's armies.  

More gunpowder often blew up more cannons, than hurling the cannonballs further.
Sadi Carnot gave formulas & numbers to his dad's cannon factory...and Napoleon's
armies soon were throwing cannonballs greater distances, with greater gun-team safety.

Study Watt, Carnot and Tesla, if you want to find the truth...
Jemes Watt is the GIANT in that trio.

​W.

Not proofed, yet



Edited 6 time(s). Last edit at 02/24/21 18:05 by wcamp1472.