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Author Topic: Bachmann Locomotives limited to 2 degree grade????  (Read 18563 times)
Desertdweller

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« Reply #30 on: May 14, 2012, 02:22:07 AM »

Don,

It all depends on the railroad.  Many shortlines do not have enough loco units to send enough out on each train to handle the steepest grade without doubling.

On the Carolina Piedmont main line west of Laurens, SC, we have a siding at the top of the grade named "Dublin".  Because that was where you had to put the first cut of cars when you were "dublin" the hill!

Les
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jward


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« Reply #31 on: May 14, 2012, 02:33:24 AM »

don,

doubling the hill is rare on the mainline but fairly common on branchlines and shortlines. when i worked with the railroad, we did it every time we lost an engine and couldn't make the hill, this was on a train which used 2 sd80macs on each end. the loss of 5000 hp due to unit failure on a 14000 ton train can make you stall out.

we also had an incident on the b&p where using the helpers at full power rolled the rail over underneath the train, putting 23 cars on the ground. after that, we were required to double mosgrove hill.

in addition to those situations, i've seen it done as standard practice on the western maryland in west virginia, out of laurel bank. it was also done on the southern up saluda mountain in north carolina. pennsy did it as well between osceola mills and tyrone, pa. like i said it was and still is fairly common.
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Jeffery S Ward Sr
Pittsburgh, PA
Doneldon

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« Reply #32 on: May 14, 2012, 04:58:36 PM »

Jeff and Les-

Sure, doubling happens on occasion on short lines, but it is truly exceptional on mainline railroads today. It's just too expensive for big railroads to have helper crews sitting around, not to mention that doubling creates choke points which would be enormous problems with the heavy usage seen on today's slimmed down railroads.

I'm not poo-pooing the fun of or need for doubling, just pointing out that economics and time pressures have made it a thing of the past except on some poorly capitalized short lines. I can't imagine any railroad which would continue to use the technique if they had a reasonable economic option not to.

Doneldon
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Desertdweller

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« Reply #33 on: May 14, 2012, 09:20:17 PM »

Don,

I'm not sure what you mean about "helper crews sitting around".  Helper crews do not play a part in doubling.
When you double, you cut off enough cars from the head end that will allow you to make the grade with the remaining cars, which are left behind on the main line.  You take those extra cars up the hill and set them to a siding beyond the crest.

Then you go back down the hill light engines, and pick up the rest of the cars.  You add the cars you took up the first time, and continue on your way.

Helpers are a way of avoiding having to double.  You keep helper locomotives and a crew on a siding before the grade, shove the train up the grade, and cut off the helpers at the top.  Then the helpers go back down to await assisting the next train.

This is not a poor use of crews if you do not have adequate power for each train, or if the traffic flow is heavy enough that the helpers can be kept busy.

It is a waste of resources to carry extra locomotives for the entire run of the train, if they are only needed for the ruling grade.  You could cut those extra locos off and leave them somewhere after besting the grade, but it would still need another crew to get them back down the hill (remember, they now have the train between them and the head of the train).

The other option is to keep the trains light enough that they can be handled with the assigned power without having to double.  Choices have to be made as to what cars have enough priority to be handled on these trains.  Then the cars with less priority (like empty cars going back to their home railroad) can be gathered into long but light trains that can run with less frequency.

It is the job of railroad field managers (like Trainmasters and Yardmasters) to make these operating decisions in a way that will best allow the railroad to operate at a profit. The answer will not be the same for all railroads.

In general, doubling is a necessary evil.  It takes a lot of time, uses extra fuel, and can cause a train crew to run out of hours before they reach their terminal.  It is used only when the alternatives are prohibitively expensive.  And as you pointed out, it ties up a mainline.

Les
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jward


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« Reply #34 on: May 15, 2012, 01:42:07 AM »

don,

just wondering what you are basing your observations on.

there are alot of factors which enter into whether or not a railroad decides to double the hill. one that many not in the industry overlook is the tractive force of the locomotive vs the coiupler strength of the cars. too much power and you break a knuckle. or worse. i've seen the coupler head ripped from the shank, all because a gp50 lost its footing temporarily, then gripped the rail again. i've also seen a situation where the frame broke on a gp38, and the whole front platform bent upwards enough for the coupler to ride up over that of the first car. run too close to the limits of the equipment, and you risk catastrophic damage.better to double the hill and relieve some of the strain, than to pull a drawbar. do that and you have to double the hill anyway, in addition to having to set out a damages car, clear the drawbar off the tracks, etc. believe me, it is a pain and attracts alot of unwanted attention to the crew.

as an example of the forces involved consider this: an emd sd80mac generates 187000 lbs of tractive force. couplers are rated at 500000 lbs.  so using 3 sd80macs on the head end of the train exceeds the rating of the couplers. if you must run 3 on the head end you either isolate one of them, or run the consist at reduced throttle settings so you don't exceed the limits of the couplers.   
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Jeffery S Ward Sr
Pittsburgh, PA
Desertdweller

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« Reply #35 on: May 15, 2012, 02:30:15 PM »

Jeffery,

I see you and I are coming from the same place on this one.

I once broke a 14,000+ton coal train in two on a 2 percent grade.  The train was powered by a mix of ES-44 and Dash 9's:  Three on the head end and and two on the rear (DP).  When I picked up the train from the BNSF at the interchange, the engineer said something about the DP units acting oddly.  They did not seem to be loading.

The first several miles were flat, and the head end power handled the train OK.  The grade started at about 1 1/2 per cent, and I got into run eight hoping to keep some momentum before the grade increased.  I left the DP power on line, mirroring the head end.  Not a good idea, as it turned out.  The rear units still were not loading.

As the head end entered the steeper part of the grade, the DP power suddenly responded to the run eight radio signal.  Now I had plenty of power, 8,000+ hp. pushing against a train with all the slack stretched out.
You already know what happens next.

After we got the train back together, I split the DP screen and ran the rear units at a lower throttle setting than the lead units.   When the train topped the grade, I put the rear units into idle for the rest of the trip.
On arrival at my terminal (where the train was interchanged to the UP), I contacted the BNSF mechanical department, and explained to the UP crew what had happened.

Les
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jward


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« Reply #36 on: May 16, 2012, 12:07:00 PM »

over here on norfolk southern's pittsburgh division, certain types of locomotives are restricted in the amount of power that can be applied in certain situations. i am no longer with the railroad, but the policies have not changed much since i was there. the locomotive fleet is divided into regular and "high adhesion" locomotives. basically, high adhesion includes everything from gp50s and sd50s up to the most modern locomotives, everything up to sd40-2s are low adhasion. this distinction is necessary because wheelslip controls evolved in about 1980 to a computer and radar based system which actually measures wheel speed against ground speed. the older systems detected changes in load of the traction motors. a slipping wheel lowered the amperage the motor was drawing, and the system would shut reduce the voltage to that motor, not the best solution on a heavy grade.

with the high adhesion locomotives, we were restricted to certain throttle settings when pushing on the rear, or using dynamic brake. full power was only used in these situations with permission on a case by case basis. when ns rebuilt the sd50s a few years back and replaced the sd40-2s in helper service with them, the engineers in the altoona helper poolhad to get used to running them in notch 6 instead of 8. they were used to pulling the throttle all the way out and shoving at full power. you can't do that with the newer locomotives. one of the things on the mainline that makes things worse is that you often have articulated intermodal cars in trains, which further restricts what you can do with the helpers. apply too much power to those and they pop right off the track. coal trains are nice because the load is evenly distributed through the train.
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Jeffery S Ward Sr
Pittsburgh, PA
Terry Toenges


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« Reply #37 on: May 16, 2012, 07:00:29 PM »

I really enjoy reading you guys' real life experiences. Very informative.
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Feel like a Mogul.
Desertdweller

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« Reply #38 on: May 16, 2012, 08:59:45 PM »

Terry,

I'm glad to hear that.  I was getting concerned we were getting a bit off-topic. If we are modeling real-life situations, it may be helpful to hear about considerations that enter into it.

One thing that is extremely important to an engineer operating a full-sized train, but is overlooked in model railroad operations, is control of slack within the train.  Coupler knuckles are made of cast iron, and are the weak link in the train.  This is by design.  A coupler knuckle is relatively cheap and easy to replace compared to, say, a drawbar.

Running slack in or out in a train is something to avoid.  Slack can be either kept run in (against the locomotive), or run out (train stretched).  If you are changing from one to the other, it needs to be done as gently as possible.

This cannot be done on a model train, because a full-size train has a braking system that can slow the cars independently of the locomotive.  It can also be worked against the locomotive to control the slack.  A model train is like a full-sized train would be if the
air was not connected to the locomotive, and the air was bled off each car.  This is only acceptable on a full-sized railroad for switching short cuts of cars within yard limits.

On the other hand, a model train decelerating is much like a full-sized train slowing with dynamic braking with no air set.  All slack in, only the locomotive providing the retarding force.

But the model train uses worm-gear drive in the loco.  A complete cut-off of power will result locked drive wheels.  Flywheels will help only slightly.  It would be the equivalent of a full-sized locomotive chopping the throttle and jamming on full independent brake.

If some designer wanted to simulate the train-handling skills used by a locomotive engineer, he would have to design a system that would provide a braking force to the cars independent of power or braking applied to the locomotive.  A system like that would be applicable to steam locomotives as well as Diesels.

Les
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jward


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« Reply #39 on: May 17, 2012, 12:40:42 AM »

i'm glad others are enjoying the insiders perspective of railroading. i've always found the real ones much more fascinating than the models. it kind of puts the models in perspective.

as an example of what i am talking about, consider somebody modelling conrail in say 1982. many modellers would look at the locomotives rostered by conrail at that time, and try to collect one or two of each type. this would be highly inaccurate, as many types were not in service due to the economy at the time. even the oddballs which were still being used were concentrated in specific areas (sd45s and sd35s in altoona helper service for example) and thus would be rarely seen on other parts of the system. to be accurate, most of the fleet should consist of just 4 models: gp40,
gp40-2, sd40. sd40-2. a smaller number should be gp38, gp38-2.  finally, one each of a couple of types like b23-7 or gp30. this would be pretty close to what you'd have seen trackside on any given day on the mainline.

regarding slack, yes it is a major problem. in my area, we weren't allowed to use stretch braking where you pull against the airbrakes set on the cars. but the pittsburgh division is a series of ups and downs. getting the train over the mountain out of altoona was the easy part. getting it the rest of the way to conway required some skill. west of johnstown, there are 3 major hills, and several smaller ones to climb. slack is always either running in or out in the train. for this reason, even relatively lightweight trains often had a helper on the rear to keep the slack bunched.

many other roads use some form of locotrol or distributed power, but while pennsy and conrail experimented with remote controlled helpers they weren't successful. i believe it is due to questions about loss of radio signal between the master and slave units. in particular, there is a nasty place known as the slide, just after you top the mountain at gallitzen. eastbound, you come out of the tunnel about 30 feet higher than the westbound tracks, and drop down a mile long stretch of 2 1/2% grade until all tracks are the same level. if you don't have your train under control on the slide, you'd better hold on and pray. you probably won't make the bottom of the mountain in altoona. the last thing you'd want is an unmanned helper losing its signal while pushing you over the top.

it is interesting that the only form of distributed power i've seen in use here is on the local trains, called shifters. these usually run with a locomotive on each end, to facilitate switching manoevers. you don't have to run around cars with a unit on each end. since the advent of the "zombie" locomotives controlled by belt pack controllers, it is now possible to control a locomotive from a half mile away using the beltpack. if the shifter is running heavy, becoming a common occurance with all the sand cars making their way to the drilling rigs in the area, the crew will often run the rear locomotive using the beltpack to get them up over the hills, while running the lead locomotive from the cab in the traditional manner.

when i modelled in n scale, slack was a major problem for me, but not in the same way as the real railroads. micro trains couplers have a spring inside the coupler which controls the slack. on long trains of free rolling cars, often these springs set up an oscillating action. the locomotive is moving along at a constant, slow speed, but the rear of the train is starting and stopping as the springs stretch and compress. the solution is the concept of stretch braking in miniature. you apply a small spring on the end of the axle on one of the wheelsets on the caboose, and thus create enough drag to keep the slack stretched. the spring applies pressure between the wheel and the adjacent truck frame.
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Jeffery S Ward Sr
Pittsburgh, PA
Desertdweller

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« Reply #40 on: May 17, 2012, 02:02:27 AM »

Jeff,

Good points there!
It appears that Altoona helper service was the last use of oddball types on the Pennsy, especially last of their type units.

I've run a lot of both BNSF and UP DP power.  When a DP unit loses radio contact with its master unit, it will keep on doing whatever its last instruction told it to do.  It then reacts to brake pipe pressure only.  If it senses an emergency brake pipe reduction, it will automatically drop to idle.

You can dump the air on the DP units the same way you would on a FRED, but if it isn't getting radio contact for control, you can't count on that.

Most of the units I have run were standard short line power.  All the units you named in your last post, plus some even older (GP7's and 9's, SD 7's and 9's.)  Several of the short lines and regionals I worked for had contracts with Class Ones in which we would use their power on unit coal trains and unit grain trains.  The coal trains generally used DP power.  We also had trackage rights to operate over parts of the BNSF and UP main lines.  One railroad served as a bridge route between KCS and CSX, and we forwarded trains over our main line with power from those two, swapping power at the halfway point so everyone's locomotives wound up back home.

I've operated long N-scale freights on club that had the bouncy coupler action you refer to.  That's a great idea to provide a little drag using coupler springs.

The full-size railroads I worked on didn't mind you using a little stretch braking if you didn't overdo it.  I know the big railroads frown on it, but it is because they feel it is wasteful of fuel.  These are the same guys who will lecture you that safety is the first consideration.  I know one guy who got fired for entering a siding on a downgrade under dynamic braking because he trying not to use stretch braking.  The rickety rail rolled over under the stress of the dynamic brake.  The defective trackwork was apparently not a consideration.

I can imagine a model railroad controller made like the desktop control console used with computer loco driver games.  A geared motor in a rear car could act as a generator for controlled dynamic braking, using the automatic brake handle on the console.

Slack action on m N-scale railroad is really not a consideration.  Almost all my trains are passenger trains.  Nine cars is a long train for me, most run six to eight cars.  My railroad is supposed to be flat, but I have to adjust my legs to keep it that way.

I model passenger operations in the 1960's because I have always been interested in passenger trains, and because they are unlike the trains I ran for a living.  I get to run all the neat stuff I didn't get to in real life: E units, F units, PA units, FA units.  Plus some I did run, GP's and early GE's.

Les
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Ken G Price


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« Reply #41 on: May 17, 2012, 06:20:21 PM »

Thanks guys, I also enjoyed the discussion. Smiley
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Ken G Price N-Scale out west. 1995-1996 or so! UP, SP, MoPac.
Pictures Of My Layout, http://s567.photobucket.com/albums/ss115/kengprice/
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