Question on grades

[nkalanaga]

VERY interesting page and a good resource.  Thank you!  I noted that he admits that he ignored rolling resistance, which is why his formula gives a slightly higher tonnage rating.  But either one will put you in the ballpark.   

For those using both steam and diesel, another factor rears its head.  Diesels are "constant horsepower" machines, which is why the TE declines with speed.  Steam locomotives are "constant tractive effort", up to the boiler horsepower limit.  All that matters for a steam locomotive is the cylinder diameter and stroke, and driver diameter.   As long as the boiler can make steam fast enough to supply the cylinders, the tractive effort remains the same, and the horsepower actually increases with speed.  The speed limit is when the boiler can no longer supply steam fast enough, or the whole thing flies apart from either centrifugal force or vibration, or the rails break from pounding by unbalanced rotating weight.  On the other hand, there is NO tractive effort, theoretically, until the pistons start moving, which is why couplers had slack.  A steamer usually had start a heavy train one car at a time.

The old saying is that a steam locomotive can pull anything it can start, while a diesel (electric) can start anything it can pull.

For comparison with the standard gauge locos listed, the D&RGW's K-36 was rated at about 36,200 TE.  On basically flat track, it was rated at 1615 tons (Alamosa-Antonito), westbound between Antonito and Chama, on 1.42%, 825 tons, but eastbound from Chama, up the 4% to Cumbres Pass, only 232 tons.

[brokemoto]

VERY interesting page and a good resource.  Thank you!     

For comparison with the standard gauge locos listed, the D&RGW's K-36 was rated at about 36,200 TE.  On basically flat track, it was rated at 1615 tons (Alamosa-Antonito), westbound between Antonito and Chama, on 1.42%, 825 tons, but eastbound from Chama, up the 4% to Cumbres Pass, only 232 tons.

It is, indeed, an informative page.

I do not know what average capacities or empty weights of narrow gauge cars were.  Thirty thousand pounds empty and a rated capacity of ninety thousand pounds, or so?  That would allow for twenty six cars on level track with fifty five tons to spare for the caboose (more than enough for that).  That seems about right.  The 1,4% grade cuts it down to thirteen cars with little to spare for the caboose and twelve with plenty to spare for the caboose.  That looks about right.  The four per-cent cuts it down to three cars with or without the caboose, although the three cars leaves plenty of capacity for the caboose.

[nkalanaga]

Most D&RGW cars were rated for 50,000 lbs, and weighed 18-23,000 lbs.  Their modern steel flatcars were stenciled 80,000 lbs, and weight 28-30,000.  Supposedly they were built from standard gauge gons, but they looked like slightly narrowed standard gauge 40 ft fishbelly sidesill flatcars.

So, fully loaded, the older equipment probably weighed 35 tons per car, and that was most of their cars, right to the end.

(Total weight corrected)

[brokemoto]

All of this discussion on weight now brings up the use of scales.  I would expect that a railroad would have  a scale in its yard.  This way, it could weigh outgoing loaded cars to make sure that they were not overloaded and to determine total train weight so that it can assign appropriate power.

I would expect that things such as mines, ore docks, coal docks, steel mills, quarries or anything that moved heavy merchandise or commodities would have a scale at the loading facility to make sure that the cars were not overloaded.

The question comes up about branch lines and short lines.  I would expect that a short line might have a scale at one of its terminals or in its yards.  Similarly, a branch line might have a scale at either its terminal or where it switches out of the main line.  This allows for the weighing of cars that are collected as the local freight heads from the main line to the branch line terminal.  The question becomes, how do you weigh cars that are collected on the way out?  Does the railroad simply take the business' word that the cars are not overloaded?  Does it collect the car and weigh it at the earliest opportunity?  In the case of a short line, if the local collects a car on the way to the interchange point with the larger road, does it let the larger road know that the car has not been weighed, thus the larger road must collect the car unweighed and weigh it at its yard?

[nkalanaga]

Most towns with a yard of any size had a track scale, even if it was a one-car-at-a-time scale on a spur, and these were usually listed in the employee timetable.  Some stations with no significant yard also had scales, sometimes for no apparent reason.  For the BN in the 1970s, it was by a letter code in the "Rule 6(A) Signs" column, which had a "Z" for track scales.  These codes were listed, in rule 6(A), in the rule book.  At that time, the BN, and many other Western roads, used "The Consolidated Code of Operating Rules".

Looking at the May 19, 1974 Spokane Division timetable, 1st Subdivision, we find scale at Whitefish, Libby, Yardley, and Spokane.  This was the old GN mainline from Columbia Falls to Sandpoint, then the ex-NP through Spokane.  The ex-GN route through Newport and Hillyard was downgraded as part of the Expo 74 rerouting in Spokane, and had scales at North Sandpoint and Hillyard.  Whitefish to Spokane was about 250 miles.  Scales were fairly common, but a car might have to travel some to reach one.

Going down to the 9th Sub, we find the branch from Hauser, on the ex-NP mainline, to Coeur d'Alene, all of 13.3 miles long.  C d'A and Blackwell were only 2.7 miles apart, but both had scales.  There isn't even a road sign to mark Blackwell, and other than the timetable listing, I have no idea where it is, in spite of being there many times.  Post Falls, on the other hand, the next station, is a fair sized town, and has a large sawmill, along with other customers of various types.  It has no scale.  The only code is Y, yard limits, not even a P for "dispatchers phone".  Blackwell has both yard limits and a phone.

There was a second line from Spokane to C d'A, which used the MILW branch much of the way.  It left C d'A by way of Gibbs, 1.1 miles west, which ALSO had a scale, along with yard limits and a "J", for the Junction with the MILW, but no phone.  Again, I have no idea where Gibbs was, as the entire MILW has been gone for years, but it also went through Post Falls.  All that's left of it is a bike trail.

Now, some related questions:  Any properly certified scale could re-lightweigh a car, if it was due, or of the shipper questioned  the weight.  The station code was stenciled on the car when it was lightweighed.  These codes DO NOT match the station/telegraph codes used in the BN timetable. 
Where did the railroads get these codes?
Was there a master list somewhere?
If two roads used the same code, how did a third road tell which one weighed the car?
Did it even MATTER which one, or was the code just to show that it wasn't "NEW"?

[brokemoto]

I know, I am reviving an old topic.  Some new questions have arisen.  I am trying to learn if I would be pushing a locomotive too hard.

The train in question requires 20.700 pounds of tractive effort to get up a long two per-cent grade.  If I want to run it at twenty five miles per hour, you multiply the 20.700 X 20 to render 517.500.  If I divide the result by 380, that renders 1.361,8421 horses required to do that or, round it up to 1.362.  If I wanted to run it at twenty miles per hour up the same grade, it would require 20.700 X 20 to render 414.000.  Divide that by 308 and it renders 1.344,1558 horses, so just to be safe, round it up to 1.345 horses.  At fifteen miles per  hour, you multiply the 20.700 X 15 to render 310.500.  If you divide that by 308 it renders 1.008,1168 or, to be safe, go with 1.009 horses.

If you assume that a locomotive rated at 1.500 horses is going to pull this train up that hill, you are getting close to the edge at twenty-five or twenty miles per hour.  The drop in required horsepower between fifteen and twenty miles per hour is significant.  It appears that you have more than sufficient horses to get it up the hill at fifteen miles per hour.

The question is:  would I be risking burning out traction motors or overheating the prime mover on a locomotive rated at 1.500 HP at any of the above speeds?   Would a locomotive that did this every day  be at risk of burning out traction motors more frequently or even suffering more frequent maintenance problems? 

By a long two per-cent grade, let it be three to five miles.

[prr7161]

With DC traction motors, this gets into the "short-time" rating for the locomotive.  Hauling near maximum TE at low speed could burn out the motors if done for a significant amount of time.  However, if I am remembering the discussion from the Contemporary Diesel Spotter's Guide, the short-time ratings were given as a time limit for running at something like 8-12 mph.  If you are getting enough TE at 15 mph you wouldn't be at risk of that.

On the prime mover, a 10-15 minute haul in notch 8 should be no problem. Helpers do that on grades over and over in a day without immediately crapping out.

[nkalanaga]

According to the BN, the continuous speed for an RS-3, with 70 mph top speed, was 10 mph.  As long as it stays above 10 mph, it can work at full throttle all day.  So, if you were using an RS-3, your 15 mph train wouldn't have any problems.

The newer C-415, also 1500 hp, had the same 70 mph top speed and 10 mph continuous speed. 

Oddly, the GP7, still 1500 hp, had a maximum speed of 65 mph, which one would think would also give a lower continuous speed.  But their CS was 11.5 mph, so something other than horsepower, number of axles, and top speed must be involved.  Maybe EMD traction motors were more sensitive to heat?

[CRL]

[brokemoto]

Thank you for the replies.  One of the things that I am getting out of the replies is that it does not matter if you are pushing the numbers on the horses.  If you have sufficient horsepower, you can run it all day as long as you keep up the speed.


The prime candidates for the job would be an ALCo RS-2 or FM H-15-44.  Also possible are ALCo FA-1, FM C-Liner (available in 1600 or 2000 HP), EMD BL-2,  Baldwin RF-16.  In addition, there are three yard switchers available:  two NW-2s and a VO-1000.  Two of the switchers would be necessary for the required HP. 

Twice weekly, there is a train of such length/weight that 43.000 pounds of tractive effort are required to get it up the hill.  Using the aforementioned equations, it would require 2.792,2077 horsepower to get up that hill.  This is within the ratings of any two of the cab units or road switchers, although close.  It would require all three of the yard switchers and you would only have just under eight horses to spare.  All of this is assuming that the rated horsepower is actually the same as that which is available actually to pull the train.  Is the name for that "taxable horsepower"?  Is the rated horsepower the same as what is available to work?   .............or is the horsepower available to work somewhat less than the rated?

At this point, we must go to the actual models:

The RS-2 and NW-2s are Kato.
The H-15-44 and VO-1000 are Atlas.
The FA-1, BBL-2 and FM C-Liner are LL, all metal frame.
The RF-16 is an E-R.

I am not a DCC user.

The NW-2s do not run well in a pair.  They will run well when paired with the VO-1000 or if you run them NW-2/VO-1000/NW-2.
The VO-1000 will run well with the C-Liner and BL-2 but only passably with the FA-1
The NW-2s will run passably with any of the LLs.
The FA/BL-2, FA/C-Liner, BL-2/C-Liner, all run well together.
The RF-16 will not run with anything.

The C-Liner has steam generator details.
I have ALCo steam generator details to fit the RS-2.
I could fashion steam generator details for the H-15-44.  They vents/escape were covered with screens that went next to the cab in the middle of the short hood (across) and in the middle of the short hood (lengthwise) on the fireman's side.  This would require some surgery.

Either FM would fit with what I want to do, which would be run steam on the passengers frequently, but use a diesel when I could.  Either FM would fit as they were maintenance hungry, thus you can justify their not being used as frequently as the other diesel(s).  The FM would run when needed on the heavier night freight and on those same days would work the passenger as well as the mid-day empty fuel cars train.  Steam would work passenger on the other days as well as the mid-day freight.. The night freight is almost always diesel powered.   

The C-Liner/VO-1000 combination might work, here, assuming a 2.000 horsepower C-Liner geared similarly to the VO-1000.  NYCS VO-1000s were geared for 60 MPH(!); the 2000 HP C-Liners for 65 and 1600s for 70.  I am guessing that there would be 60 MPH gearing available for a C-Liner.  A short line could get away with running a yard goat and a cab unit in MU a couple of days per week.  The horsepower would be 3000 and tractive effort 76.800 pounds combined; more than sufficient.  Both Baldwin and FM u sed Westinghouse electricals.  If the VO-1000 was a wartime assignment worked so hard during the war that it went back to Baldwin in the early 1950s for rebuilding, it could have been rebuilt with a Westinghouse electric throttle (those were available on Baldwins, although most had pneumatic.  In addition, there was available an adapter from Baldwin, but few roads used it.) .  The Westinghouse electric throttle that Baldwin used was the same as that in the FM C-Liner.  The VO-1000 would fall short in required horsepower, even for the usual night freight.  This could be addressed by using the Short Creek Junction station switcher as a helper

The road switchers would be more useful to the short line.  NYCS RS-2s had a 32.500 pound rating at 14,2 MPH.  NYCS had no H-15-44s, but its H-16-44s were rated at 48.500 pounds.  The total available  horses would also be 3000.  Thus, all ratings are sufficient.  NYCS had RS-2s geared for 65, 75 and 85 MPH.  The H-16-44s were geared for 70 MPH.  I am guessing that similar gearing for one o r the other would be available.  This would require the surgery to the H-15-44, as I would want the FM sidelined so that I could  run the steam.  The FM would require far more maintenance than would the ALCo.  There would be no need for a helper on the ruling grade for the usual  night freight, as either the ALCo or FM would have both sufficient horses and tractive effort on their own to get the train up the hill.

I could use the three yard switchers.  This would keep the passenger trains all steam.  The three yard switchers would push the tight spaces in one town, though.  Two would work for the usual night freight, but the heavier one would require all three.

As this is a short line, although it is a busy one, I am trying to keep the roster at no more than three diesels and three steam.  The other power lettered for it can be swapped in if I must take one out of service.  Right now, the BL-2 is sidelined until I can do something about one of the Kato #4s whose points it likes to pick.  This is the only one whose points it likes to pick.  It will run over the others.