Has there been a change in where 'helper' engines are placed in trains - especially long ones?It seems to me that in the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle.Is this an actual change or am I just waking up to an old trend? If new, why the change? Does radio part of the expaination?
STOLOFFHas there been a change in where 'helper' engines are placed in trains - especially long ones? It seems to me that in the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle.Is this an actual change or am I just waking up to an old trend? If new, why the change? Does radio part of the expaination?
It seems to me that in the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle.Is this an actual change or am I just waking up to an old trend? If new, why the change? Does radio part of the expaination?
Most Class 1's have gone to the operation of Distributed Power Units (DPU). The DPU's are place in and/or behind the train in a effort to minimize the in train draft and buff forces and thereby get the train over the road with a lesser potential of broken knuckles or pulled out draft gear. The engineer on the lead locomotive consist has control of all the DPU's engine consists in his train. There can be multiple DPU's engine consists in a train. The DPU engine consists can be multiple units in MU control of the designated DPU unit.
My former carrier is now operating trains that previously ran with two units on the head end with one unit on the head end and one unit as a DPU back near the middle of the train or in some cases on the rear of the train. Still two units total.
Manned helper districts, as a practical matter, have become a thing of the past.
Never too old to have a happy childhood!
Yes, to say it another way, you are not seeing helpers. You are seeing Distributed power. Distributed power is run from the lead engine.
Distributed power has been around for decades. The primary vendor is GE with their Locotrol product. Even back in the 70s-80s "snoot nosed" SD40s had this.
A HELPER is usually a manned helper, a group of engines run by a different engineer. THose are very rare.
However, railroads will still add an remove extra engines which are effectively helpers, but those engines are added into the main control.
For example, Union Pacific generally runs trains with a 3-2-0 configuration 3 engines up front, 2 mid train, zero on the back...however, for the big trains heading over the Sierras, it will add an additional 2 or more engines on the front for a 5-2-0 config. Those engines come off in Salt Lake City.
STOLOFFin the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle.
timz STOLOFF in the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle. Far as we know, "helpers" on the rear are as common as ever, except on the longest trains where they think maybe the remote control won't work reliably the length of the train. UP used to have a rule that rear units were supposed to be within 8500 feet of the head end.
STOLOFF in the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle.
Far as we know, "helpers" on the rear are as common as ever, except on the longest trains where they think maybe the remote control won't work reliably the length of the train. UP used to have a rule that rear units were supposed to be within 8500 feet of the head end.
Manned 'Helpers' are basically a thing of the past. Even in the day of manned helpers there were 'trailing tonnage' restrictions that governed the placement of helpers and sometimes the manned helper had to be positioned within the train to prevent the head end power 'stringlining' the train account the trailing tonnage.
BaltACDManned 'Helpers' are basically a thing of the past.
Likewise while snapping as a general practice has come to be de-emphasized as a practice in PSR, it may gain distinctive emphasis should line utilization or other things become important for true actual 'precision scheduling'.
It helps to consider how this stuff works with Expedient Monster Consists™ by looking at Don Oltmann's now seminal blog post... 2040 now being less than a quarter-century away.
As others have said, what you see are DPUs. Manned helper operations are dead everywhere except for a few shortlines and Montana Rail Link on Mullan Pass. MRL however has been doing the same practices that have been done for decades before MRL existed, placing helpers in the middle or rear depending on the length of the train.
DPUs are starting to be placed where cuts will be made when the train arrives at the next yard. I wonder if the trend of longer trains and more distribution based on cuts will continue and follow Don's predictions
Max Karl, MRL and BNSF
Max KarlI wonder if the trend of longer trains and more distribution based on cuts will continue and follow Don's predictions
And it is that model that 'snapping' specifically enables: the ability to separate monster trains on the fly, like a horribly-mutated Atlantic Coast Express service, with autonomous snappers (ideally energy-storage-enabled electric or dual-mode-lite II) coming out of pockets to push each section uphill with only CBTC separation between them, then cutting off at a logical point for opposing moves with the following train closing the gap and coupling again to run under common DPU authority...
This is speed to keep a one-speed railroad precise, not to give faster end-to-end service time...
MRL also uses manned helpers over Bozeman Pass. Usually on the rear, but (depending on the type of train) sometimes on the head end. MRL occasionally uses manned helpers on Evaro Hill when heavy trains get sent that way due to MofW, derailment, or other "blockage" impacting the lower-grade line through St. Regis.
CN does not allow the DP remote to be more than 10,500' behind the lead consist, on 100% intermodal trains this distance is increased to 12,000'.
On trains with multiple remotes the distance is virtually unlimited, I think we initially had a bulletin limiting length to 16,500' but I can't find it right now.
I believe the remotes will relay radio signals between each other and the lead consist on such a train. At any rate these trains seem to have less trouble with comm loss than a 11,000' train with only one remote on the very tail end.
They like to put the remote halfway or 2/3 of the way back on most trains, though intermodals and some shorter unit bulk trains can have it on the tail end. Under our rules the first 5 cars ahead of the remote consist must be loaded, this is increased to 10 if the consist has two or more units.
The best handling trains are those with a remote halfway back and another on the tail end. A 200+ car loaded unit grain or coal train runs way smoother if set up 1x1x1, compared to 2x1x0 or 2x0x1.
Greetings from Alberta
-an Articulate Malcontent
Max KarlAs others have said, what you see are DPUs. Manned helper operations are dead everywhere except for a few shortlines and Montana Rail Link on Mullan Pass. MRL however has been doing the same practices that have been done for decades before MRL existed, placing helpers in the middle or rear depending on the length of the train. DPUs are starting to be placed where cuts will be made when the train arrives at the next yard. I wonder if the trend of longer trains and more distribution based on cuts will continue and follow Don's predictions
To utilize DPU in mountainous terrain the communications systems of the line have to be upgraded with radio repeaters to assist in maintining communication between the leader and the in train DPU's.
Installing repeaters in difficult terrain is costly as in most cases access and electricity are difficult and expensive things to come by.
Helper or Distributed Power, here's how UP does it.
ssi.pdf (up.com) Helper placement information is in Item 5. It even has diagrams.
It's not the current SSI, so some parts of it have changed. I think the helper placement is pretty much current. It gives an idea anyway.
Jeff
STOLOFF Has there been a change in where 'helper' engines are placed in trains - especially long ones?It seems to me that in the past the helpers were ganged at the front or placed at the rear of a long train but recently I've noticed they are being placed in the middle.Is this an actual change or am I just waking up to an old trend? If new, why the change? Does radio part of the expaination?
It depends on the railroad. Southern Pacific used to have helpers in the middle of the train and not the end. I think the SP helpers were manned, though. Most class 1s now use locomotives as DPUs, they are unmanned and controlled by radio.
~FanOfTheRail
Didn't the SP put them in more at the 2/3 of the train with the remain 1/3 trailing the helpers?
In about 1973 SP put specific instructions in the timetable -- the train's tonnage was allotted to each engine in proportion to their horsepower, and each entrained helper was supposed to be positioned to shove 1/3 and pull 2/3 of its allotted tonnage. So if the road engine and helper had the same horsepower, the helper was supposed to have 1/3 of the total tonnage behind it. (If there was only one helper.)
The practice of putting helpers or remote power two-thirds back was also to equalize brake response
There is science involved in helper placement. The science involves the amount of trailing tonnage and the drawbar pull that it creates in conjunction with the amount of gradient and degree of curvature involved on the specific territory - coupled with the weight/length of cars and their location within the entirety of the train.
Mere childs play.
CSSHEGEWISCH The practice of putting helpers or remote power two-thirds back was also to equalize brake response
Manned helpers will cut out their automatic brake valve once in place. The only brakes the mid-train or rear helper engineer has control over is the helper's independent (engine) brakes. The lead engineer (if their is a helper in front of the train's engineer, that helper engineer would be the lead engineer) controls the train's (automatic) brake.
If the in-train or rear helper has it's automatic cut-in and the engineer is out of or misses communication with the head end, the helper may not realize a brake application has been made by the lead engineer. The helper with it's brake still in release will try to charge the brake pipe ahead of it. If the helper does realize an application is being made and doesn't make an equal or greater application, the helper will try to maintain the brake pipe at the helper's higher pressure. Either scenerio could cause some cars to have an unintentional release.
Distributed power remote engines do have their automatic cut in. On current DP equipment, the air brakes on the remotes do exactly what the controlling engine does. If the engineer makes a 10 psi reduction, the remote(s) also make a 10 psi reduction. DP remote air brake control can't be indepently operated from the lead. Only throttle and dynamic brake control can be independently operated on remote consists.
I asked a friend who is a CN engineer how they decided where to put DPUs.The primary answer was to place DPUs to maintain good air pressure for breaking throughout the train. The other reasons presented elsewear are also true.
Are manned helpers used by NS on Horseshoe Curve?
Keep in mind that Horse Shoe is a special case, a consequence of the decision to concentrate the major Allegheny crossing grade into a fairly short length of track with facilities at either end.
While DPU consists could be used for helping, they would be useful only for a comparatively short portion of an overall run. They are not needed either for snapping or higher speed when the train is not on the grade, as PSR generally does not value the increased fuel burn. In the absence of autonomous operation it would be time-consuming and tedious to add and configure DPU helpers at one end of a district containing the 'hill' and then cut them off, hostle them, etc. at the other end,in addition to the opportunity cost of the power held out of more general use to be connected as DPU for the limited but very necessary service.
In short, it makes sense to use manned helpers if there is frequent traffic during the duty time of the crew, where the ability to attach quickly to push and then cut off on the fly is valuable (as it is over Horse Shoe), and where helping in both directions is required within a relatively short district...
Is the location where helpers cut off atop Horse Shoe visible from any publicly accessible place?
Still in training.
A friend's hubby recently retired from UP as KC yard hostler. He sometimes had to run as a helper to get the train over Lee's Summit. He was qualified as engineer over the road too so would help as needed. Any train I have seen in recent years has a DPU on the rear or sometimes in the middle of train too.
Lithonia Operator Is the location where helpers cut off atop Horse Shoe visible from any publicly accessible place?
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