Western Railroad Discussion > CTE Questions

I have some questions about the CTE used on GE locomotives. I have an idea of what it does, but:

1. How does it work?
2. Is it a software thing or is it hardware related, or both?
3. Is it only available on AC lokes (AC4400)?
4. Is it standard equipment or an option?
5. Are the GEVOs (ES44AC/ES44DC) equiped with it?
6. Did other RR's beside UP utilize it?
7. How is it controlled in the cab?
8. Are there visual indicators that indicate whether CTE is applied or running normal?
9. What effect does CTE have on throttle settings?

All other info on it is appreciated. TIA.

Lane.

Lane asked:

"1. How does it work?
2. Is it a software thing or is it hardware related, or both?
3. Is it only available on AC lokes (AC4400)?
4. Is it standard equipment or an option?
5. Are the GEVOs (ES44AC/ES44DC) equiped with it?
6. Did other RR's beside UP utilize it?
7. How is it controlled in the cab?
8. Are there visual indicators that indicate whether CTE is applied or running normal?
9. What effect does CTE have on throttle settings?"



1. How does it work?
2. Is it a software thing or is it hardware related, or both?


Software for the most part, controlled from lead unit.

3. Is it only available on AC lokes (AC4400)?

So far, AC4400CWCTEs only.

4. Is it standard equipment or an option?

Option.

5. Are the GEVOs (ES44AC/ES44DC) equiped with it?

Haven't heard of any being so equipped.

6. Did other RR's beside UP utilize it?

UP only to my knowledge.

7. How is it controlled in the cab?

As part of DP, would be part of that set up and linking. I am not sure if the CTE unit has to be the receiver, but I beleive it must be, and it would then control the rest of the units in that remote set.

8. Are there visual indicators that indicate whether CTE is applied or running normal?

Probably not.

9. What effect does CTE have on throttle settings?

CTE reduces the setting for the DP units to a lower level than the lead locomotives. The DP sets cannot run at full throttle when the CTE is activated.

Hope this helps.

KK

GP40X Wrote:
-------------------------------------------------------
> I have some questions about the CTE used on GE
> locomotives. I have an idea of what it does, but:
>
> 1. How does it work?
> 2. Is it a software thing or is it hardware
> related, or both?
> 3. Is it only available on AC lokes (AC4400)?
> 4. Is it standard equipment or an option?
> 5. Are the GEVOs (ES44AC/ES44DC) equiped with it?
> 6. Did other RR's beside UP utilize it?
> 7. How is it controlled in the cab?
> 8. Are there visual indicators that indicate
> whether CTE is applied or running normal?
> 9. What effect does CTE have on throttle
> settings?
>
> All other info on it is appreciated. TIA.
>
> Lane.


Let's try this again:

> 1. How does it work?

It electronically causes the remote units to operate at roughly a 10% reduction in tractive effort below 15 MPH. The controlling locomotive on the remote consist (the one you're linked to) has to be equipped with the CTE feature and the feature has to be selected during the linking process.

> 2. Is it a software thing or is it hardware related, or both?

Basically a simple software control of the remote units when used in a remote mode. Operating the same unit manually as a manned helper will not allow for the CTE feature to function as this is only available in DP mode.

> 3. Is it only available on AC lokes (AC4400)?

It is to my knowledge a "UP only" feature introduced on the C44AC-CTE (5700's) and then continued on the C45AC-CTE units. There are older C44AC units and C60AC units but I cannot confirm with 100% accuracy if these are also equipped with this feature (I do believe they have been upgraded though but don't quote me on that). I am also not sure about the status of the newer SD-70ACe units UP got as to whether they have this feature (I believe they do but I have never had the need to investigate this yet).

> 4. Is it standard equipment or an option?

It is an option.

> 5. Are the GEVOs (ES44AC/ES44DC) equiped with it?

See #3 above.

> 6. Did other RR's beside UP utilize it?

So far UP is the only railroad that I know of using it but then again I am not really familiar with other railroads and their DP practices.

> 7. How is it controlled in the cab?

It is activated during the linking process. Once activated there is nothing for the engineer to do differently as far as operating the DP train.

> 8. Are there visual indicators that indicate whether CTE is applied or running normal?

The DP control screen can be made to show if the DP units are linked in "CTE Mode" or "FTE Mode" (full tractive effort, meaning the CTE software is not enabled). FTE mode is used in case where tractive effort is not required to be reduced, an example being if the C44AC-CTE unit is MU'ed with a smaller DC unit and thus isn't exceeding the powered axle restrictions for helpers.

> 9. What effect does CTE have on throttle settings?

None, other than covered in answer #1 above.

What's the purpose of CTE if you were wondering???


Loaded rail cars can usually weigh up to 140 tons or 280,000 lbs.

Say two locos on the rear of a train were putting out 140K lbs of effort each, this would probably be under 10 MPH in Run 8 on any modern 4000-4400HP AC loco.

Together, that would be 280K lbs of effort being pushed on the last car of the train.

The lateral/vertical ratio is simple....to keep the cars on the track, keep the vertical force (gravity - 280,000 lbs for a 140 ton car) greater than the lateral force (buff and draft forces).

I don't know UP's policy on when to set up the DP in CTE mode, but I would guess it would be when there are two or more locos on the rear of a train where the grades and HPT are going to make train speeds under 15 MPH in run 8. Probably on manifest freight I would say. Loaded coal trains or unit bulk commodity trains are safe with two units on the rear.

Not sure how much CTE limits tractive effort on the rear power, but I have heard it was limited to either 100k or 110K, thus reducing the risk the lateral forces exceeding the vertical forces aka shooting/lifting cars off the track.

frnocom Wrote:
-------------------------------------------------------
> I don't know UP's policy on when to set up the DP
> in CTE mode, but I would guess it would be when
> there are two or more locos on the rear of a train
> where the grades and HPT are going to make train
> speeds under 15 MPH in run 8.

UP helper rules involve "restricted tonnage" ahead of the helpers, both rear and cut-in, and certain make-up requirements within this restricted tonnage. This restricted tonnage is also dependent on axles of power (C44AC-CTE units are rated at 12.1 axles of power). With a maximum axle rating of 23 axles on the rear of a train two of the C44AC-CTE units would exceed this. This is where the "CTE Mode" comes in by electronically reducing the powered axles to acceptible levels. Basically linking a C44AC-CTE unit in CTE mode the unit is then rated at 11 axles instead of 12.1 axles. There is more to all this but that's more than needed here.

> Not sure how much CTE limits tractive effort on
> the rear power, but I have heard it was limited to
> either 100k or 110K, thus reducing the risk the
> lateral forces exceeding the vertical forces aka
> shooting/lifting cars off the track.

The total tractive effort isn't actually limited to a specific level but simply reduced by about 10% of the maximum for the unit.

copy

Thanks, to all, for the responses. I'm now more informed.

CP's Evolutions also have it.

The overall purpose of "CTE" is to purposely degrade an AC unit so that it will only produce the tractive effort equivalent to a Dash-9 at low speed (roughly 110,000 pounds of TE at 10-11 MPH instead of the normal 135,000 pounds for an AC unit). Any other AC unit MU'd to the CTE DP unit on the rear-end also goes to CTE mode through the 27-pin trainline MU cable circuits.

Two Dash-9s is the maximum rear-end helper power UP will use on a "non heavy haul" train (mixed manifest, for example), to avoid jack knifing the rear end of the train.

The engineer selects the mode he/she wants the DP consists to operate in ... FTE (full TE) for heavy haul/bulk service, or CTE (controlled TE).

The FTE/CTE functionality results in the AC units so-equipped being much more flexible, swinging between heavy haul/bulk, intermodal and manifest services. Plus, putting AC units in helper assignments takes advantage of their AC motors and avoids the classic issues involved in having DC units operated in DP mode (hot, stinky motors).

Incidentally, "equivalent powered axles" equates any unit (AC or DC) to a plain jane SD40-2, which has 6 equivalent powered axles (EPA). The TE of the AC unit, for example, is divided by the "standard" TE of an SD40-2, I believe 60,000 pounds ... and that ratio is multipled times 6 to get the EPA for the AC unit, for example.

just to clarify on a few things, the UP EMD SD70ACe's are CTE equiped as well and are the only other units to be so equiped besides the late model AC4400CW's and replacement ES44AC's.
Also all the older UP AC4400CW's are being upgraded with the CTE software and reclassed C44ACCTE from C44AC when this takes place. With this taking place there is no real reason to add the CTE designation as all of these units will be so equiped.

Bryan Jones
Brooks, KY
Bryan's Train Photos

Also all the older UP AC4400CW's are being upgraded with the CTE software and reclassed C44ACCTE from C44AC when this takes place. With this taking place there is no real reason to add the CTE designation as all of these units will be so equiped.

Are the former SP 100-199 also being upgraded to DP capability as they are shopped and repainted/patched???

KK