LPTP #8... destination reached, more or less

archae86
archae86
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RE: I think it just eats

Quote:
I think it just eats snow. :-)


Mike, I think you have that right. A much more modern arrangement in current Russian service is the CM-2 type, which attacks the snow at the front, and moves it to the back of the lead machine by a sort of conveyor mechanism. This dumps the snow to the first of series of gondola cars, each of which has a bottom conveyor mechanism to move the snow on to the next.

This page has lots more pictures and detail. The one that surprised me is that the last gondola can dump snow track side. So maybe the concept is that the gondolas are just temporary storage to get past confined areas where trackside disposal is not suitable.

David S
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Phil, Coal stokers are

Phil,

Coal stokers are pretty standard in medium sized locomotives and larger. However, they aren't always maintained in working order. At Illinois Railway Museum, Frisco 1630 returned to service this season after a 10-year rebuild. Last I heard, the stoker is not operable. However, she doesn't use a whole lot of coal on a small operation like this.

I'm in my first year of volunteering and am ready to qualify as an operator on Chicago Surface Lines 3142, a 1923 Brill streetcar. During the 15 year restoration of this car, they acquired traction motors from Alexandria, Egypt. It runs nearly every weekend for five months per year.

David

Miserable old git
Patiently waiting for the asteroid with my name on it.

TimeLord04
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Good morning everyone. :-)

Good morning everyone. :-)

TimeLord04
Have TARDIS, will travel...
Come along K-9!
Join SETI Refugees

Mike Hewson
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RE: RE: Mike, I think you

Quote:
Quote:

Mike, I think you have that right. A much more modern arrangement in current Russian service is the CM-2 type, which attacks the snow at the front, and moves it to the back of the lead machine by a sort of conveyor mechanism. This dumps the snow to the first of series of gondola cars, each of which has a bottom conveyor mechanism to move the snow on to the next.

This page has lots more pictures and detail. The one that surprised me is that the last gondola can dump snow track side. So maybe the concept is that the gondolas are just temporary storage to get past confined areas where trackside disposal is not suitable.


That makes sense. On a mountainside you just toss it off as you can and probably it doesn't matter much where it lands, but on flat plains there may be an amenity problem with stuff adjacent to the track. Hence storing and sorting as it were. They also scrub and clean around the tracks to ground/sleeper level to be sure. I note the Ukraine has substantial rail and rail-side infrastructure around it's grain production.

Our local valley effort is here. While the line had gone out of regular use some 30 years ago, the fires of 2009 destroyed much of the bridging - that being of wooden construction. The ultimate aim is to rehabilitate around 10 miles of track across gentle undulations at the valley floor. There is one tunnel about 150 yards long.

Quote:
I'm in my first year of volunteering and am ready to qualify as an operator on Chicago Surface Lines 3142, a 1923 Brill streetcar.

Go for it! :-)

An auger fed coal fire is a beastie, eh? It's amazing that Nick Carnot worked out a few major law of physics ( conservation of energy, entropy trends ) simply by thinking about steam engines. He wrote that in his own terms of course, but he was exactly right. The key expression is for maximum efficiency of a heat engine :

1 - T_c/T_h

T_c is the absolute temperature of the 'cold spot' ( the environment generally for steam trains ) and T_h is the temperature of the 'hot spot' ( eg. the firebox ). You never get 100% ie. you always lose some available energy as heat ( so that's the entropy statement ) and the very best efficiency for any hot/cold spot differential is for fully reversible devices ( a theoretical abstraction only approached in the limit of real devices ). As one can't do much about T_c then a really well fed firebox will burn quite hot, not only outputting more power in toto but a greater fraction converting to motive power when all the sums are done.

This has an interesting, and possibly counter-intuitive, implication here : all else being equal, a given steam engine will be more efficient in cooler circumstances ( eg. winter, night-time ) than hotter scenarios ( eg. summer, day time) ! :-)

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Phil
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RE: This has an

Quote:
This has an interesting, and possibly counter-intuitive, implication here : all else being equal, a given steam engine will be more efficient in cooler circumstances ( eg. winter, night-time ) than hotter scenarios ( eg. summer, day time) ! :-)

Another interesting fact. Steam engines produce more tractive effort the faster they run, as opposed to todays diesel-electric, which produces more tractive effort at low speed.

It can be quite frustrating for a modern train crew. As you slow down while climbing a grade your wheels will lose traction from too much power and start to slip, further reducing your speed. Sometimes we get more traction at a LOWER throttle setting which can reduce slippage.

Phil

Mike Hewson
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RE: RE: This has an

Quote:
Quote:
This has an interesting, and possibly counter-intuitive, implication here : all else being equal, a given steam engine will be more efficient in cooler circumstances ( eg. winter, night-time ) than hotter scenarios ( eg. summer, day time) ! :-)

Another interesting fact. Steam engines produce more tractive effort the faster they run, as opposed to todays diesel-electric, which produces more tractive effort at low speed.

It can be quite frustrating for a modern train crew. As you slow down while climbing a grade your wheels will lose traction from too much power and start to slip, further reducing your speed. Sometimes we get more traction at a LOWER throttle setting which can reduce slippage.


Absolutely. Traction is where the action is ! This is a fascinating and typically non-linear area of study - the friction of railways. You need some friction to produce a traction force parallel to the tracks and thus move around and about. No point otherwise. You don't want too little as even if you do get going you want to stop at some place and time of choosing. Furthermore you don't want too much as that saps the useful energy available. That leaves rather a bit of a goldilocks and three bears scenario.

If you will permit a digression ( and I hope I'm not telling you how to suck eggs as it were ). It turns out to be extra-ordinarily difficult to rigorously derive from deeper principles ( eg. quantum mechanics ) why it is even approximately true that the frictional force along the rail is linear proportional to the ( reaction ) force normal to the rail.

Certainly if one assumes that as true, then that easily explains why slipping is easier on slopes as some of the vehicle's weight is not acting in the normal direction, pushing harder on the track. Thus when going up a steeper grade the normal lowers, the friction lowers and thus your traction may be lost. That cuts both ways ie. running downhill it will be harder to pull up as friction is needed there too.

Now the Swiss got into those ratchet arrangements on steep climbs, a third/middle rail that meshed tooth & cog with a driving component on the car. It turns out that, up to a point, 'ordinary' friction might be seen as similiar. Both the wheel rim and rail upper surface are in close detail like rugged mountain ranges, so one could model as 'cog to cog' coupling mesh-like and giving purchase. But as we are not talking of a ( nano- ) engineering match of specifications here, then inevitably some 'lifting' or displacement in the normal direction has to happen. Roughly speaking a higher force compressing the two surfaces together will negate that up and down travel, the 'cog teeth' remained engaged, and there ( somewhere ) lies the origin of the normal force influencing the friction parallel to the interface. Evidently the detail is horrendous here for any seriously realistic model. But this also sort of explains why heat typically lowers friction, as the rumbling of the micro landscape on either side ( due to randomly directed oscillations of the material's lattice ) will tend to add to those normal displacements that encourage slippage between the surface profiles. Hence hot brakes can be very less effective, we pay much attention to cooling them by various means, though friction adds to the heat content of the components to boot.

Over longer timescales the peaks and valleys of these profiles tend to wear to flat ( as heat increases especially ) and entire slabs of this micro landscape are tossed away. Abrasion and destruction of the pieces. Things become smooth, the 'cogs' are stripped of their teeth, and parallel grip reduces. Oddly enough rusting of steel may assist to maintain friction here, as while a rail becomes shiny smooth with wear, ongoing rust will pit and roughen the surfaces without any special attention. The jagged profiles regenerate in the oxidising atmosphere that Earth has. Eventually entropy wins ..... :-) :-)

Cheers, Mike.

( edit ) Now there's an idea! The UN's WHO has asked ~ 200 researchers ( well outside of the UN's normally close & cuddly circle of 'accredited experts' ) about what to do with Ebola. Gee, who would have thunk it possible? No doubt they wanted to not appear to be incompetent ( as an overlay upon their standard state of actually being incompetent ). Fortunately ideas abound, but for US researchers one key obstacle remains : will the FDA not prosecute them for fast-tracking vaccine release by avoiding the normal time-consuming ethical analysis pathways typical of that category of products ? Stay tuned folks ...... and let's see if the WHO can get up to speed with that old logic that relates smoke to fires.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

mikey
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RE: But this also sort of

Quote:

But this also sort of explains why heat typically lowers friction, as the rumbling of the micro landscape on either side ( due to randomly directed oscillations of the material's lattice ) will tend to add to those normal displacements that encourage slippage between the surface profiles. Hence hot brakes can be very less effective, we pay much attention to cooling them by various means, though friction adds to the heat content of the components to boot.

So you are saying they need carbon/carbon brakes like F1 race cars have, they NEED to be HOT or they won't work at all. In fact most drivers have a problem with their brakes cooling off too much between braking events.

Quote:
( edit ) Now there's an idea! The UN's WHO has asked ~ 200 researchers ( well outside of the UN's normally close & cuddly circle of 'accredited experts' ) about what to do with Ebola. Gee, who would have thunk it possible? No doubt they wanted to not appear to be incompetent ( as an overlay upon their standard state of actually being incompetent ). Fortunately ideas abound, but for US researchers one key obstacle remains : will the FDA not prosecute them for fast-tracking vaccine release by avoiding the normal time-consuming ethical analysis pathways typical of that category of products ? Stay tuned folks ...... and let's see if the WHO can get up to speed with that old logic that relates smoke to fires.

It would seem to me to be 'well since they asked and you are willing to help we will give you an exemption in this ONE case' time. 'For the better good' and all that kind of stuff. Like when they used to test stuff on prisoners, giving them reductions in their sentences if they agreed.

Phil
Phil
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RE: So you are saying they

Quote:
So you are saying they need carbon/carbon brakes like F1 race cars have, they NEED to be HOT or they won't work at all.

The brakes on a train will work cold, but yes, they do work better when "warmed" up a bit. We see this everyday during normal operations.

It also takes some time for the brake pipe to draw down. Lowering the air pressure in the brake pipe is what causes the brakes to apply. The brake pipe, or trainline, is an airline going the full length of the train. When the engineer lowers the pressure, it tells each car to feed air into the brakes on that car from a supply tank on each car. Since the air in the line is bleed down from the engine, it takes time to release air that may be 2 miles away on a long train.

If the train breaks in two, or air pressure is lost for any other reason, each car applies its own brake system. Very simple, and failsafe.

Phil

Bill592
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RE: If the train breaks

Quote:

If the train breaks in two, or air pressure is lost for any other reason, each car applies its own brake system. Very simple, and failsafe.

Phil

That is all very interesting Phil, However, I am now putting the 'brakes' on your previous status as WINNING !!!

Bill

David S
David S
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RE: RE: So you are saying

Quote:
Quote:
So you are saying they need carbon/carbon brakes like F1 race cars have, they NEED to be HOT or they won't work at all.

The brakes on a train will work cold, but yes, they do work better when "warmed" up a bit. We see this everyday during normal operations.

It also takes some time for the brake pipe to draw down. Lowering the air pressure in the brake pipe is what causes the brakes to apply. The brake pipe, or trainline, is an airline going the full length of the train. When the engineer lowers the pressure, it tells each car to feed air into the brakes on that car from a supply tank on each car. Since the air in the line is bleed down from the engine, it takes time to release air that may be 2 miles away on a long train.

If the train breaks in two, or air pressure is lost for any other reason, each car applies its own brake system. Very simple, and failsafe.

Phil


I recently took the museum's air brake class and still remember most of it ;)

Having done that, I'm approved for line training as coach train conductor, but I'm not as far along with that as I am with the streetcar (on which the brakes work entirely differently -- straight air).

Carry on winning.

David

Miserable old git
Patiently waiting for the asteroid with my name on it.

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