Engines on the back of freights question

paul 2 posted:

Watching web cams especially the Rochelle cam when the freights go through they have one or two engines on the rear. So they are remotes controlled by the engineer. My question?? When it comes to stopping along with the throttling down of the engines are the air brakes applied in these engines too. Thanks Paul

Yes. The Engineer has total & complete control of the rear DPU (Distributed Power Unit/Units) from the lead/controlling units. Thus, when he/she applies the train brakes, the front AND rear units apply the train brakes at the same time.

HOT WATER, thanks for the answer. Never would of known brakes could be applied from both ends..........Paul

paul 2 posted:

HOT WATER, thanks for the answer. Never would of known brakes could be applied from both ends..........Paul

Plus, the brakes are released, i.e. pumped back up, from both ends. Thus providing much smoother train handling, resulting in far fewer break-in-twos.

In my neighborhood the KCS uses a lot of DP, especially on coal and grain trains.  The odd part is that one coal train may run with 2 on the head and 3 on the rear and the next one may be 2 on the head, 2 about 2/3 back and 1 on the rear.  I haven't had a chance to talk with anyone that would know (actual railroad employee) and ask why one coal train runs 3 x 2 or 2 x 3 and the next one is 2 x 2 x 1. 

KansasMike posted:

In my neighborhood the KCS uses a lot of DP, especially on coal and grain trains.  The odd part is that one coal train may run with 2 on the head and 3 on the rear and the next one may be 2 on the head, 2 about 2/3 back and 1 on the rear.  I haven't had a chance to talk with anyone that would know (actual railroad employee) and ask why one coal train runs 3 x 2 or 2 x 3 and the next one is 2 x 2 x 1. 

The placement of DPU power throughout a unit coal train is mostly dictated by the coal mine and/or the unloading site at the power plant. Very few, if any, coal mines throughout the Powder River Coal Basin, allow mid-train DPU power since such placement up-sets the flood-loading of the 100+ car unit coal trains. I've see what happens to a nice new SD70MAC when the coal delivery operator screwed up and "loaded" 130 tons of coal on top of a mid-train DPU!

If one can find an old SP employee timetable of the 1970's, look in the back.  There were serveral formulas about where to place helpers.  At that time the electronic controls for the remotes were not as robust as today's.  Plus there were no AC traction motors on diesels.

History of another period.  

My guess there are like formulas for today if DPU units are placed on a train.

KansasMike posted:

In my neighborhood the KCS uses a lot of DP, especially on coal and grain trains.  The odd part is that one coal train may run with 2 on the head and 3 on the rear and the next one may be 2 on the head, 2 about 2/3 back and 1 on the rear.  I haven't had a chance to talk with anyone that would know (actual railroad employee) and ask why one coal train runs 3 x 2 or 2 x 3 and the next one is 2 x 2 x 1. 

Don't know about KCS, but here in the Orange Kingdom I see BNSF shuttle trains (ethanol, grain) with engines on both ends.  Usually it's 3/2 or 2/3 but it can be 1/3 or 3/1.  I think what you're missing is these trains aren't uncoupled--they are unit trains.  Train pulls empty hoppers to the elevator (usually a big circle track), loads the grain, and simply hops into the cab at the other end of the train and takes it back on the line it came in on.  

paul 2 posted:

HOT WATER, thanks for the answer. Never would of known brakes could be applied from both ends..........Paul

Not only that, but the distributed power locomotives can either be synced to mimic the power, brake and dynamic settings of the lead unit, or be set up to operate independently.  If you have a long train cresting a big hill, the lead units can be in dynamic brake while the units out back can still be pushing the train over the hill.  Not a task for beginners.

Dieselbob posted:

paul 2 posted:

HOT WATER, thanks for the answer. Never would of known brakes could be applied from both ends..........Paul

Not only that, but the distributed power locomotives can either be synced to mimic the power, brake and dynamic settings of the lead unit, or be set up to operate independently.  If you have a long train cresting a big hill, the lead units can be in dynamic brake while the units out back can still be pushing the train over the hill.  Not a task for beginners.

I bet, could imagine a plethora of things that could go wrong there.

Hot Water posted:

I've see what happens to a nice new SD70MAC when the coal delivery operator screwed up and "loaded" 130 tons of coal on top of a mid-train DPU!

Whoops! That would be funny to see. 

Two23 posted:

KansasMike posted:

In my neighborhood the KCS uses a lot of DP, especially on coal and grain trains.  The odd part is that one coal train may run with 2 on the head and 3 on the rear and the next one may be 2 on the head, 2 about 2/3 back and 1 on the rear.  I haven't had a chance to talk with anyone that would know (actual railroad employee) and ask why one coal train runs 3 x 2 or 2 x 3 and the next one is 2 x 2 x 1. 

Don't know about KCS, but here in the Orange Kingdom I see BNSF shuttle trains (ethanol, grain) with engines on both ends.  Usually it's 3/2 or 2/3 but it can be 1/3 or 3/1.  I think what you're missing is these trains aren't uncoupled--they are unit trains.  Train pulls empty hoppers to the elevator (usually a big circle track), loads the grain, and simply hops into the cab at the other end of the train and takes it back on the line it came in on.  

Actually they often "break" coal and grain trains here to install engines in the middle of the train.  The unit trains arrive in Pittsburg from Kansas City and will often need extra helpers for the SB grades as they head to Heavener Oklahoma.  Extra power is stored here and the yard is setup to ease the insertion of power mid train.  Again not all are placed in the middle of these unit trains, but it is not uncommon to see.

I have noticed one thing.  When the KCS is using Union Pacific run thru power on the head end, it is more likely  to see power in the middle of the train. 

Dominic Mazoch posted:

If one can find an old SP employee timetable of the 1970's, look in the back.  There were serveral formulas about where to place helpers.  At that time the electronic controls for the remotes were not as robust as today's.  Plus there were no AC traction motors on diesels.

History of another period.  

My guess there are like formulas for today if DPU units are placed on a train.

I would guess that computers and algorithms might be used now to calculate the most efficient placement of engines for each individual train, based on a number of variables, such as load tonnage, distribution of load tonnage, power of the individual diesels to be used, route travelled including factors such as grades encountered enroute, speed requirements and achievement of optimum fuel economy.

There is another use of engines at both ends.  Interchange of a train in unusual trackage.

Suppose a SB BNSF train needs to be interchanged with the KCS, SB.  The trackage at Rosenberg TX requires a reverse move to complete the interchange.  If the power is going through, and is at both ends, great.  BNSF hands over train to KCS.  KCS checks train over.  Now, the crew now uses what was the rear set as lead, and the ex front becomes the rear.  No switching needed!

breezinup posted:

Dominic Mazoch posted:

If one can find an old SP employee timetable of the 1970's, look in the back.  There were serveral formulas about where to place helpers.  At that time the electronic controls for the remotes were not as robust as today's.  Plus there were no AC traction motors on diesels.

History of another period.  

My guess there are like formulas for today if DPU units are placed on a train.

I would guess that computers and algorithms might be used now to calculate the most efficient placement of engines for each individual train, based on a number of variables, such as load tonnage, distribution of load tonnage, power of the individual diesels to be used, route travelled including factors such as grades encountered enroute, speed requirements and achievement of optimum fuel economy.

It has traditionally not been quite that sophisticated.  In the early days of remote consists, the remote consist of the same horsepower was placed behind approximately 67% of the train's total tonnage.  That way the two consists were  Balanced in what they were moving, and the radio signal was more reliable than when the remote was just ahead of the caboose.

When I left railroad employment in 2007, there was a formula in the Special Instructions, for figuring in-train placement of remote consists that was designed to balance in-train forces and avoid buckling the train by shoving against blocks of empties with loads ahead of them.  The formula had to be re-figured every time the train set out or picked up cars, and was not popular as a result.  Mostly, these days, I see mid-train remotes only in mountain grade territory on unit trains consisting of cars of similar weight.

With trains of intermodal equipment that need to begin and end their trips in yards, mid-train helpers are placed so as to be accessible to the hostling crew who will take the engine to the service area.