• Question RE: SD40-2 helpers on Horseshoe Curve

  • Discussion related to the operations and equipment of Consolidated Rail Corp. (Conrail) from 1976 to its present operations as Conrail Shared Assets. Official web site can be found here: CONRAIL.COM.
Discussion related to the operations and equipment of Consolidated Rail Corp. (Conrail) from 1976 to its present operations as Conrail Shared Assets. Official web site can be found here: CONRAIL.COM.

Moderators: TAMR213, keeper1616

  by Jim in S.E. Pa.
Hi guys,
I hope there may be an SD40-2 hogger here who has worked helpers on the curve, and can shed some light on the following.

The link below is a freight that was stopped on the curve. Before they started rolling again the helpers were thottled up for quite some time. At the first sign of movment, it sounds like they throttle down or come under the load. I was wondering what exact course of events are occuring here. Were the TM's engaged while he was throttled up? And at the time they started to roll did he throttle back to prevent "squirting" cars? Seems to be some confusion in the comments posted to the video also.


Thanks in advance.

  by rswinnerton
He's got them throttled up to help the head end build up air in the brake pipe. As the air in the pipe gets past 80psi, the head end starts to pull. On the rear, these guys are still building pipe pressure up to 90psi. When the rear starts to move, the helpers throttle back, move the reverser to the forward position, and throttle back up to start pushing. It's done this was because 1) Builds air faster and 2) keeps the train from rolling back down the mountain.

Hope this helps!
  by Jim in S.E. Pa.
Thanks Russ. That explains it clearly.

PS: Just noticed I spelled "Horseshoe" wrong...Oh well.....lol
my old conrail ec-99 air brake book says the air is to be cut out on the helpers when they are trainlined. the rule is, only one engineer has the air. are you telling us the rear helpers are charging the train line? along with the head end? while i never worked this part of the railroad in my conrail days,what you describe above seems odd,did you work on the mountain in helper crew service? Also,I dont ever remember having to revup the SD-40-2's to build the air when I ran them. We were always told these units charge the same at idle or notched out. Please explain.
  by jgallaway81
The trouble here is there is no way to tell whats going on. WHY did they stop in the first place? How big was the train?

While I can't say that charging the brake pipe from both ends was never done, I've never heard anyone admit to it.

IF the train stopped because the helper had already reached his short-time ratings, then the stop would have been to cool the traction motors. In that case, the reverser is centered, the generator field switch is left up, and the throttle is advanced to notch eight. There is some correlation between throttle position and TM blower speed. (The current rulebook says to advance to notch eight for ten minutes to cool the motors). Engineer could have been doing that, kept the engine in "cooling mode" and told the head end he was ready. Only when the release reached him, did he throttle-off, drop the reverser forward and notch back out again.

Another possible reason for the stop was a stop signal at MG, just a bit up the curve, or perhaps a bad signal at 242.

There are just too many possibilities to truly know what happened.

Another possibility is that it was just a coincidence. I didn't work the 40-2s long enough to know their complete characteristics, but the new 40-Es have a "cool-down" cycle for the main engine. If the engine has been running hard and then is throttled off, the engine will actually speed up rpms to allow more cooling air to be run through the radiator. It could have been that the engines sped up to cool off while sitting and just happened to have reached the end of the cool-off cycle when they started pulling out again.
  by rswinnerton
As Mr Gallaway points out, it could have been for any number of reasons, however the notes at the end of the video mention that they were doing tunnel work at Gallitzin, which was probably the tunnel cut-over project. While I never ran helpers over the curve, I have been told by guys who did that this was sometimes done against the rule to get trains through the construction zone faster when things started to back up (and they often did). It could, however have been the traction motor blower situation mentioned aswell.
  by rswinnerton
Also, while you don't have to rev the locomotives to build air, the shaft-driven air compressors build air faster at higher RPM, and would therefore fill the trainline faster. The helpers also would not be in control of the air when moving, just to help charge.
The video is in two parts,and i agree there is NO WAY to know what was going on here. One night coming up to Pattenburg tunnel we hammered(rings of fire on all the wheels from spinning) one of those SD-40-2's into the ground, it being a single unit on a heavy train with no sand.. I never remember it going into a cooling cycle ,but its been a while, as this was the mid 1990's. also,if i remember correctly, over charging the hind end of a train will result in stuck breaks (not releasing) if the head end is has lower lower break pipe pressure. IF any one is telling secrets about breaking AIR rules best to not post that info here. After watching part one and two,to me it looks like the train is being held stopped with the power,that is without the air being used. right before it stops you can hear the cars creek because the slack is highly bunched. There really is no reason to help charge the train unless there was a bad trainline leak. thats how I see it . Bob Gottschall
  by Jim in S.E. Pa.
The train was stopped on the curve because of some blasting being done up ahead. I dont know how many cars they had on, but it was quite a long train with 4 units on the head end along with the two helpers.

  by jgallaway81
4 units on the head end, plus a 2unit helper. The 4 units on the head end are, unfortunately, not very diagnostic of train size. were they 4 geeps, 4 helpers, 4 40w's? Not trying to be a jerk, just explaining why I said its not diagnostic. Also, additional units on the head end could simply be a power move, though, as I understand it, Conrail was more inclined to run a light power move for the purposes of balancing power on the system, where as NS seems to prefer consisting them, dead-in-tow.

Another factor to consider... was there any automatic shutdown timers in service on CR at this time? I know it seems a silly question, but I've seem some archaic looking systems installed on ex-CR units. If that was possible, its also possible that the helper engineer had the throttle advanced to delay/override the shutdown timer.

Honestly, I think its best just to let this one rest. There are simply WAY to many possibilities to conclusively say WHY the engine was spun up, throttled off, and throttled back up.
After thinking back to those Conrail SD-40-2's. we had at least some with M.P.R.C. (manual power reduction control)dials (1-10)to limit the voltage to the TM's. The engine stays reved, gen.voltage high but less current to the TM's. Works like a hump control, not to be confused with SELECT-A-POWER systems. Pretty shure we used it once or twice at Saucon yard at Bethlehem Steel(steep grade),put away alot of ore trains there in my time as a conductor.
  by jgallaway81
Ya, I have seen those units, but I thought they worked by reducing the power available at each step of the throttle by a certain percentage.
  by Jim in S.E. Pa.
Sorry for asking this question.. It seems to have sparked abit of a debate.
I was happy with the plausable explaination offered at the top, but didnt expect what followed.
I simply asked the question so I could pass on an answer to someone who had seen the vid and asked me about it.
I thank you guys for your time and effort.
As for Mr Gallaway. Im sorry if I dont meet your standards as to technical expertise, but I am not an expert on equipment. I thought knowing why the train stopped would be enough info.. I was wrong. You read so many other aspects into the subject that you lost me. So I'm gonna take your advice and just back out of this one...


PS: Whoever corrected the spelling in the topic title.....Thankyou
I'm glad the question was asked. got me to thinking about things so easily forgotten when you leave the railroad and don't do everyday. Sometimes on boards like this and even in print media,people that never worked in the field offer answeres up and people take it as gospel. Railroaders will sometimes tell fans things just to tell them,the fan not knowing the difference thinks this its true. the old saying "a little knowlege is a dangerous thing" could apply here. I just wish someone that actually worked as "Altoona helpers" as they were called would chime in,but you never know who reads these boards NS Mgmt. included. Bob Gottschall, Conrail Freight conductor 1990-1998
  by jgallaway81
Jim, I sincerely apologize if my response came off being prickly, that certainly was not my intention. I am not sorry you asked the question, it was a good question.

In saying that we should just leave the question as is, was meant that all the options given here are all equally valid, and unfortunately, without, say, the engine's event recorder tapes, theory is all we will be able to give at this point. I just can't give you an absolutely 100% gaurenteed correct answer.

Bob, I unfortunately turned 18 the month after the great blue sale. However, I now work out of Altoona off the extraboard and frequently operate the 6300 series engines in helper service. In fact I just got done this morning shoving the 19g over to Pittsburgh, (I believe 19g equates to the OIPI?).

Sitting here, I'm thinking how I would bring a train to a stop on the curve. As the headend engineer, the first thing to be done is inform the helper of the planned stop, and that I was applying the air. I would stay in full throttle and apply approximately 10lbs air while bailing off. As soon as I detected the brakes grabbing hold, I would begin gradually throttling off in order to prevent excess amperage from building up and ripping a knuckle. In number three throttle, I would allow the train to stall and apply the independent brake fully. As soon as the brake cylinders showed at least 50psi, I'd throttle down to #2. When the independent reached full pressure, I'd throttle to number one and make certain the brake was holding before throttling completely off.

As the helper, I would also stay in full throttle while the air was applied. Bailing off the helpers, I'd watch the amp gauge and make the first throttle reduction when I saw the amps begin to rise. After each throttle reduction, I'd wait until the amps began to rise again and then throttle off again, holding at #3, or maybe even #4 until we stalled out, in order to ensure the rear portion of the train stayed bunched for when we got ready to pull out again. Once stopped, I'd follow the same pattern of applying the independent and throttling off as I would on the head end.

Getting ready to pull out once we were given the okay (figuring that a flagman was protecting the blasting zone), I'd first contact the helper and make certain that he heard we were ready to pull west. As soon as he acknowledges, I'd let him know I'm releasing the air. As the air began to flow, I'm make certain the generator field switch is up and the reverser forward and throttle out to number one. Once the helper said he had the release and was coming up, I'd throttle up to number three while knocking the independent off in #2. Depending on train tonnage, I may wait in #3 or throttle up to #4 and hold until I felt the train moving forward, at which point I'd begin throttling up to get underway.

As the helper, as soon as the headend said "here comes the release" I'd throttle up to #3 and knock off the independent. Once the release reached me, I'd throttle up another notch and let the headend know that the release had reached me and that I was coming up against him. Keeping an eye on the amp gauge and the ground (to gauge actual speed) I'd begin throttling up to take up slack and start shoving the head end out, so they knew it was safe to start throttling up.

Even with that, the problem is that its impossible to know if the rev-up before starting was a manual or automatic effect. There are several conditions on the 40-Es that will cause the engine to automatically rev up... hot turbo's, hot engines, hot traction motors or other electrical components, low air pressure, cold cooling water (I doubt that one is possible considering the climb up from Alto already, but I mention it to show there are many conditions).

Another possibility is that the throttle had been advanced for a certain amount of time while stalled and the engine automatically throttled down to collect slack and then began throttling back up to try to move by taking up the slack it just generated. I saw the remote yard engines do this... two days ago? trying to pull a very heavy cut of cars up out of the lower yard in Altoona. And, no, its not a remote phenomenon... what I don't know is if it is a switcher thing.