Call me an idiot, but .....?

Here's my 2 cents.The only added benefit to AC units is the fact that they maintain dynamic brake amperage to a stop whereas on older units the dynamic fades away below 6 mph.And they also seem less prone to ground relays.As for a break in two with a DPU train once the remotes go into emergency there are steps you would have to follow to put the train back together.DPU trains work through a combination of radio signals and brake pipe pressure.When a DPU train is separated you would have to put the system into set out mode.That tells the remote units that the depleted brake pipe condition is desired.Then you could recover the air on the head portion without the remote starting to try to pump the trainline back up.If you don't go to setup mode when you send the air back to the rear portion of the train you would just go into emergency again as soon as air started reaching the remotes.As for the brakeman...they don't care if we feel labor starved.And they don't care how long it takes you to complete a task.They would rather save on the wages of another employee.They figure they own us for 12 hours and if it takes that long...too bad for us.As for the poor conductor having to tie 30 or 40 hand brakes to hold a train on a heavy grade in a blizzard....tough.They don't care.That's when i'm glad to be an engineer.What really frosts them is when you tell them to hurry and shut the door they're letting all the heat out lol.Just kidding!(kinda) :-) And as for anxiety they say a locomotive engineer is a very high stress job.And to some it is.You can tell the nervous ones though.They get that intense look of concentration and it's hard to get them to shoot the bull while they're running.I guess i'm lucky though because for the most part the job rarely stresses me out.It can have it's moments though.

Edit You are correct,the moment the head end goes into emergency the loss of brake pipe pressure at the rear will cause the remotes to PC.The remotes might push for a second or two longer than the head end but it would be almost instant.As a matter of fact if the break in two was at the rear the remotes would go in emergency before the head end did.It would be a matter of which power consist got the loss of the air signal first.Once it's in emergency there's not many things we have our hands full with really.Basically you place the brake valve in the emergency position and attempt to control the slack by bailing the independent brake.Whatever the slack condition of your train is, you try to keep it that way.I know it might seem to you that we would be very busy, but to a good engineer it's instinctive.When your running you think in more than one dimension.Not only where your going but where you've been and what your train is doing.A new engineer might get a bit lost in the moment but a veteran will do the necessary steps instinctively.As for the set out mode i mentioned that comes after your stopped.The first thing after you stop is you try to recover your air to see if your train is still in one piece.If it's not the remotes wouldn't do anything because the system has no pressure in the brake pipe(the radio signal would be telling them to recover but like i said the radio signal goes hand in hand with the brake pipe pressure.So even though your telling them to recover without them having brake pipe pressure they won't do it).So they won't recover and start charging the trainline.Then the poor conductor hits the ground and starts looking for the problem.If your in two he would close the angle cock on the head portion.That would allow the engineer to recover the air on the front half.The remotes would have to be put in set out mode or they will just keep going into emergency.Set out mode tells the system there's no air in the brake pipe but that it's a desired condition and to "look" for the air to return in the brake pipe.

Too many questions rolled together here, try to stay short and concise, it makes it easier for people answering.

As for AC units, from the engineer's seat I see very very little difference, if you took off the stenciled designation on the front of the cab I woulndt know the difference. There is a little bit of difference in traction control but when they do slip, it tends to be all the axles at once and I have been involved in 2 break in twos because of that.

I think the manufacturer's told the RRs a big story and they believed it.

As for tieing down a train, not that hard, in the old days the rules called for a train to be tied down on the downhill end, and if you were going uphill, the handbrakes would be applied on the rear, without cabooses it was inconvenient to have the brakes a mile and a half away so, rather than waste time, they compromised safety and now we just tie the handbrakes on the end closest to the locomotives.

Your statement about the slaves pushing when the train goes into emergency is partially correct, they will still shove for awhile and make a possible derailment worse.

However these new series of DPU engines are much much better than the first ones we had back in the 70s so that helps.

Overall, I like the DPU, it makes you look a lot better than you really are.

I would have to agree with Andy, they have us for twelve and that is the ONLY criteria they look at for decision making. Which crew is going to die next.

I didn't read the last post you reffed to about AC motors v. DC motors in regards to breaking power. I can't say I notice a difference either. We have some brand new DC GE motors that seem to have the strongest dynamic breaking bang for the buck but that wouldn't help you when recharging on grade. The only true difference I see is that here with our mountain grade we have to call manned helpers to shove all of the grain trains because of AC motors they use on them. This is supposedly because the AC motors over heat much easier and can't be in run 8 (max power) for 3+ hrs. The coal trains and the grain trains are generally pretty even in regards to horse power v. tons or HPT but because of the AC motors we shove the grains.

As far as breaking in two on a DP train it happens all the time here. Well perhaps not breaking in two but having to tie trains down to recharge.My explorer loves to run trains at the absolute minimum HPT they can. So where a UP train running over the same track might have 6 units with 3 different consist for 120 coal loads, we have 2 2 unit consist. So any little problem with any engine and your conductor is tying the train down so you can go grab the nearest emergency motor. When this occurs we have a responder come out to help the conductor with a ride. We also have mechanical responders and senior "mentor" engineers who can come out to help us with mechanical issues so we can try and trouble shoot issues. But none of this help saves the conductor from having to tie 45 hand brakes in 3ft of snow should we loose an engine for any reason. Some accountant somewhere has done the break even analysis that it is cheaper to order 12 relief crews every time some one melts down on the hill than it would be to have an extra engine on all the cycle trains. It is what it is, I am just glad I still have a conductor so I don't go crazy talking to myself for 12 hrs.

LOL. My first good chuckle of 2012. Thanks for that. Let's take 'em one at a time.

Believe it. But as with all things, there are limits. You are not going to be able to hold a whole lot of tonnage with two locomotives on a descending 2% grade, for an example. But there are many places where holding significant tonnage on a grade is absolutely doable, IF we are talking AC units.

Why AC units?

The truth is, most diesel electrics have always been an AC engine, the juice being supplied by the AR10 main alternator. The current produced is AC, but then passed through banks of rectifiers that converted the juice to DC to feed it to the DC traction motors, the most common of those being the D77 for EMD locos. Of course energy is lost in the conversion and the excess is dissipated as heat. So the change has happened at the motors, not so much on the supply side, if I'm correct.

But reversing a DC engine will pit contactors, generate a tremendous amount of heat and damage will occur after a time to motors, rectifiers and cabling feeding the motors. On an AC engine, all that stuff is out of the formula, because it isn't there.

But it should NEVER be a substitute for securing a train in emergency. What if you figure wrong and your units can't hold the train? Now you get pushed out by the train coming after you with no air in it. That's when things start to shape up for a really bad day.

So when would you use it at all? If you release from a minimal grade to get the train moving, you can hold them for a minute or two of recharge time before you start the actual movement.

In short, legal, doable, inadvisable. Best not to get yourself into a jackpot in the first place and it all becomes moot.

A crash course in the alphabet:

IPS: Our friend the Independent Pressure Switch. On locomotives with extended range dynamic brake, as the train is coming to a stop and you begin to apply the engine brakes, the IPS will nullify the extended range as a measure to guard against sliding wheels as they come to rest. They are set nominally at 15psi.

DBI: Dynamic Brake Interlock. Not all units have them, but what it does is when you make a reduction in the brake pipe while in dynamic brake, it will automatically keep the independent brake from applying. When in power, you must depress the independent handle to "bail off" to keep the engine brakes from applying. Most of us make it a habit to bail off anyway when in dynamic, in case of a mixed consist or foreign line engines.

PC: Pneumatic Control valve. Results inn a "penalty" application of the brakes, like hitting the over-speed limit, or if not responding to a prompt from an alertor, as examples.

P2A: When the PC trips an initiates a penalty application, this valve interrupts flow of air from the main reservoir and reduces the equalizing reservoir to full service, which with a 90 psi brake pipe (BP) is 26 psi. It does not put the train into emergency with a penalty application. It also nullifies power and puts the prime mover back to idle. Most locos these days will have dynamic brake still available for a short period when experiencing an emergency application of the brakes. This is strictly for slack control to keep a train in one piece.

When the PC trips due to an emergency application of the brakes, it performs the above function and in addition engages the A-1 Charging Cut Off Pilot valve, which will not allow for anything to get into the brake pipe. It will not allow for recharging until after the equalizing reservoir has been brought to zero for a predetermined amount of time. This guarantees the brakes will not release until you are ready to do so and AFTER THE TRAIN IS SECURED.

The trains are critically under staffed. Those of us who have been around for a while will recall that when "Conductor Only" agreements were first being kicked around it was though that there would be one or two people available to travel where the train is in trouble at, kind of like the old "section" principal for the MOW forces.

Didn't happen.

Not only are there only two men on a crew, they are exhausted, because the carriers will not maintain an adequate supply of man power and opt to work existing employees until they are ready to drop.

If I'm not mistaken, ALL carriers are STILL making record profits, even in this down economy I think last quarter of fiscal 2010 was a bit over $400 million for the UP, so I can understand their terrible financial crunch.

The public is being fed a huge bullcrap sandwich.

Thanks for asking!

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