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Eastern Railroad Discussion > Some DPU Questions


Date: 06/11/19 13:50
Some DPU Questions
Author: Tominde

I'm still trying to learn DPU.  Some questions:

1.  Is DPU "portable".  Not in the sense of hand held, but can a control box be readily swapped to a non DPU locomotive?

2.  What radio frequency range, modulation are they using?

3.  What happens when radio contact is lost temporairily? 

4.Does the control box have both transmitter and receiver so it can lead or follow.   Most DPUs that I see on the old B&O Baltimore - Philly line are facing opposite directions.  I assume this is mostly done to facilitate returning the power back the other direction. Correct??

5.  I haven't followed engine numbers closely but do DPU units tend to stay paired together?  I haven't looked closely at cabs, is there a notation indicating "DPU equipped", or is it the computer just knows the road number?

5. Are the brakes on a DPU set up like a trailing MU?        Can the air on the DPU be used to rechrage the train line?   



Date: 06/11/19 17:46
Re: Some DPU Questions
Author: HotWater

Tominde Wrote:
-------------------------------------------------------
> I'm still trying to learn DPU.  Some questions:
>
> 1.  Is DPU "portable".  Not in the sense of hand
> held, but can a control box be readily swapped to
> a non DPU locomotive?

No.

> 2.  What radio frequency range, modulation are
> they using?

I have no idea.


> 3.  What happens when radio contact is lost
> temporairily? 

The rear DPU stay in their current state, unless a train line air brake reduction occurs, then the drop load and go to idle.

> 4.Does the control box have both transmitter and
> receiver so it can lead or follow.

Yes.

Most DPUs
> that I see on the old B&O Baltimore - Philly line
> are facing opposite directions.  I assume this is
> mostly done to facilitate returning the power back
> the other direction. Correct??

Sound logical.


> 5.  I haven't followed engine numbers closely but
> do DPU units tend to stay paired together?

Maybe that depends on the railroad, but I doubt it. A DPU is a DPU and can be linked up with any other DPU within a train consist.
  I
> haven't looked closely at cabs, is there a
> notation indicating "DPU equipped", or is it the
> computer just knows the road number?

Yes.


> 5. Are the brakes on a DPU set up like a trailing
> MU?        Can the air on the DPU be used to
> rechrage the train line? 

Yes and yes.  



Date: 06/11/19 18:39
Re: Some DPU Questions
Author: mttrainman1

A little clarification on your last question. The controlling locomotive of the remote dpu consist mirrors the controlling locomotive of the of thr lead dpu consist. This allows the engineer to control both the independent (loco) brakes and the automatic brakes. This automatic brake feature is one of the high-lights of distributed power. When the engineer applies the automatic brake, the remote dpu consist also automatically applies the automatic brake farther back in the train. This results in a much faster and more even train brake application. After the desired amount of brakes are applied and the engineer releases the brakes by charging air back into the train, the remote dpu also assists in charging the train. This improves release times and makes it less likely that the train can be ripped apart by the engineer pulling while the brakes are still releasing on the rear of the train. This feature allowscfar longer trains to be run. Dpu trains can be finicky when excessive leakage occurs but other than that, i think it is alot easier to operate once the fundamentals are learned.

Posted from Android



Date: 06/13/19 06:28
Re: Some DPU Questions
Author: engineerinvirginia

As to how DP engines know each other....when you do the initial setup, you TELL the computers which engines they will be linking with. The only caveat is that on initial setup the master and remote units have to be at least 35 feet away from each other. (You can't make a DP set out of two engines that are coupled...for example)...but it's convenient to have the units side by side to link them when you are building the train. 



Date: 06/13/19 17:19
Re: Some DPU Questions
Author: ble692

engineerinvirginia Wrote:
-------------------------------------------------------
> The only caveat is that on initial setup the master and remote
> units have to be at least 35 feet away from each
> other. (You can't make a DP set out of two engines
> that are coupled...for example)...but it's
> convenient to have the units side by side to link
> them when you are building the train. 

Wait what?

The UP routinely links engines coupled nose to nose at the roundhouse without any issues. Just did it myself last week. And how would the engines know they are more or less than 35 feet from each other?



Date: 06/13/19 17:32
Re: Some DPU Questions
Author: SanJoaquinEngr

engineerinvirginia Wrote:
-------------------------------------------------------
> As to how DP engines know each other....when you
> do the initial setup, you TELL the computers which
> engines they will be linking with. The only caveat
> is that on initial setup the master and remote
> units have to be at least 35 feet away from each
> other. (You can't make a DP set out of two engines
> that are coupled...for example)...but it's
> convenient to have the units side by side to link
> them when you are building the train. 


Actual initial set up all of the units are coupled into one consist. Once they are linked and air tested load tested. There are other set up procedures and buttons that are done to complete the process. When a train is being built the DPU unit is set out and the train is then shoved to the unit and normalized. Air tested and ready to depart the terminal.

Posted from Android



Date: 06/13/19 18:01
Re: Some DPU Questions
Author: HotWater

ble692 Wrote:
-------------------------------------------------------
> engineerinvirginia Wrote:
> --------------------------------------------------
> -----
> > The only caveat is that on initial setup the
> master and remote
> > units have to be at least 35 feet away from
> each
> > other. (You can't make a DP set out of two
> engines
> > that are coupled...for example)...but it's
> > convenient to have the units side by side to
> link
> > them when you are building the train. 
>
> Wait what?
>
> The UP routinely links engines coupled nose to
> nose at the roundhouse without any issues. Just
> did it myself last week. And how would the engines
> know they are more or less than 35 feet from each
> other?

Agreed. Can't tell you how many times I was involved in "linking up" lead and trail units for DP service right there in the engine terminal, at either Alliance, NE or Guernsey, WY, on BN/BNSF. The BN/BNSF Mechanical Dept. personnel did it on a daily basis, well within "35 feet" of each other. The radio transmitters & receives don't have any idea what the minimum distance is, only the maximum distance, when communication drops out.



Date: 06/14/19 03:56
Re: Some DPU Questions
Author: howeld

I didn’t see fence covered. Engineers have the ability to also independently control the DPU by putting up the “fence”. Used in hilly terrain where the front may be downhill in Dynamic and the rear still pushing. Also very importing when starting on a grade. Notch up the rear before the headend.

Posted from iPhone



Date: 06/14/19 05:18
Re: Some DPU Questions
Author: ldstephey

Good stuff.  Thanks.



Date: 06/14/19 05:28
Re: Some DPU Questions
Author: dcfbalcoS1

      Taking a common sense guess on this one but the RR's probably would just as soon you DON'T know the frequency in these days and times. I also suppose I am way wrong on that and that it could be common knowledge and the units are safe from tampering by outsiders.



Date: 06/14/19 19:38
Re: Some DPU Questions
Author: engineerinvirginia

35 feet is our rule....rules never make any sense



Date: 06/19/19 12:39
Re: Some DPU Questions
Author: SD45X

And it takes planning to get a nose out DP unit:)
Usually grab a unit and tack it on and link up. Setup asks if it faces the same or opposite direction as the leader:) some idiots can’t read that step in the setup screen:) had to fix one run 65 miles with alarm bells. Inbound engineer is an idiot.

Posted from iPhone



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