Mixing of Diesel Power

[Anonymous]

Most engineers prefer a matched set because the loading is fairly equal. But on the otherhand it doesn't happen very often. When I used to assemble the outbound consists in Roseville for the UP, we would have to use what we had. The only trains that left on a regular basis with a matched sets were the ones that were running up and down the I-5 corridor from L.A. Ca. to Portland Or. Most of those units were the SP SD70's.

[Anonymous]

QUOTE: Originally posted by taylorl

I've noticed on long freights that you see a mixture of GE and EMD engines in the consist. You sometimes see a GE on the point or an EMD. Does a GE or EMD engine pull better by being on the point or does it matter at all? I assume that when trains are made up you take what you have and run with it?

Larry

First, They all pull together, Second, What's up front does not matter. It's all a really a matter of what is available at the time. Any forget all the BS over how they work together. Even GP-7's and GP-9's did not load up the same.

[Anonymous]

QUOTE: Originally posted by taylorl

I've noticed on long freights that you see a mixture of GE and EMD engines in the consist. You sometimes see a GE on the point or an EMD. Does a GE or EMD engine pull better by being on the point or does it matter at all? I assume that when trains are made up you take what you have and run with it?

Larry

[adrianspeeder]

What are some examples of locos that couldnt be MU'ed do to brake differences?

Adrianspeeder

[mvlandsw]

The AC's have no short time ratings. They can be run all day at any speed. The new DC unit also protect themselves from traction motor damage by limiting their amperage when the motors get too hot, so there is no problem in running them with the AC units.

[zardoz]

If memory serves, the thinking behind the grouping of locomotives has to do with short-time ratings of the traction motors.

Today's newer locomotives have a much enhanced capacity for high amperage, compared to second-generation (SD40-2 & earlier) models. If the engineer has modern locomotive[s] in the consist along with an older model, there is the possibility he might forget about the old unit and burn up the traction motors on it. In order to protect the old unit, the entire consist would have to be operated according to the short-time ratings of the oldest locomotive, thereby wasting much of the 'new" power.

The situation is even more critical if the newer equipment is an AC propulsion unit, as those have incredible short-time ratings that will melt even the newest DC locomotive's motors.

Most of the problems I encountered when connecting different types of locomotives in MU service was in the air brake system. Of course, I am speaking from the days when one might have as many different types of automatic and independent brake valves in as many locomotives. Connecting a unit with a 6BL with a unit with a 6BLC with a unit with a 24RL with a unit with a 26L brake valve can cause all sorts of interesting brake operations, especially when trying to position the MU2A valve on each locomotive correctly; and of course, each combination was different depending on which unit was leading. There were many times I never left the diesel ramp with the assigned power, because not even the shop forces could get a variety of locomotives to MU correctly.

And many times when a locomotive in the consist was not operating properly, the cause of the fault would be in the 27-point jumper that is used to electrically connect the locomotives.

[espeefoamer]

Any builders units could MU with any others except for Baldwin which had a different MU system.However once I did see a three builder lashup on the SP in 1973 that consisted of a GE U25B,Baldwin S12,and EMD GP35.With the Baldwin in the middle,there was a crew in each engine.

[CSXrules4eva]

I guess it all depends on the engineer's personal preference when it boils down to it. I personally think EMD builds the better engine, and their trucks are far more superior than GE's trucks. The HTCR II truck blew the HIAD truck away. Many engineers that work for Conrail and CSX have told me they like the preformance of EMD HTCR II truck better because, of it's steering cappabilities which makes the ride so much smother through out shap turns. It's also equiped with center pivit pins that eliminate more weight at the trailing axle and less weight of the leading axle.This makes it less suseptable to wheel slip. The steering linkage, traction rods, and steering beams on the HTCR II eliminate pestistols and, it's liners. BUT, all in all the both are building good locomotives.

[Anonymous]

QUOTE: Originally posted by gabe

If you are interested in this sort of thing, you should check out Norfolk's Southern's fairly recent decision to group certain locomotives together. I wish I could remember the exact cite and I can't find it right now because I am in my office. Does anyone else remember where this information can be found?

Nothing really came of that rule, I only saw it being used for a couple months (the most usual train during that time was an intermodal with a soon-to-be-retired B23-7, a soon-to-be-rebuilt GP38AC high hood, and a GP40-2).

[Anonymous]

QUOTE: Originally posted by taylorl

Thanks for the info. Sounds like it really doesn't matter and you take what's given to you and run with it.

Larry

Yup pretty much.

[daveklepper]

Freights operating in the corridor have to have a lead locomotive with the Corridor's ATC and cab signal systems. This applies to both fast Norfolk Southern freights and the CSX, Gilford, and Providence and Worcester local freight trains, There is also a special signal system on the old RF&P if it is still being used.

[Anonymous]

Thanks for the info. Sounds like it really doesn't matter and you take what's given to you and run with it.

Larry

[BentnoseWillie]

Position in the consist makes no difference in how a locomotive pulls. As a rule, the hostler will throw whatever's convenient in the lead position, unless there are labour agreements or government requirements involved that certain units meet and others do not.

For example:

• BC Rail engines can't lead a CN train outside of BC until they're fitted with microwave ovens in the cab per CN's labour agreement.
• Most US engines cannot lead a train in Canada, because they lack an event recorder and a reset speed control device, as required by federal law.
• Some of the old Pennsylvania railroad now operated by NS is controlled by cab signals, so trains in this territory have to be led by a locomotive so equipped - generally former Conrail engines.

As for how fast engines load, GE's are reputed to load up slower than EMD's do, although that has little if anything to do with where it is in the consist.

Last but not least, MU systems have been universal for decades. I think the last oddball system was Baldwin's, and they've been out of the diesel locomotive business for nearly 50 years.

Hope this helps!

[CSSHEGEWISCH]

I understand that an engineer can feel the difference when advancing the throttle in a lash-up of different makes as to which units are loading up faster. Beyond that, I don't think that there's any real difference. MU control systems are a lot more compatible now than in the early diesel days of the 1940's and 1950's.

[gabe]

If you are interested in this sort of thing, you should check out Norfolk's Southern's fairly recent decision to group certain locomotives together. I wish I could remember the exact cite and I can't find it right now because I am in my office. Does anyone else remember where this information can be found?

I seem to remember the article saying something about the grouping of EMDs and GEs as well.

Hope that helps,

Gabe

[Mookie]

If I remember right - they told me it doesn't make a difference. You get what they give you and what's available. Having said that - I notice here - the point on coal is usually EMD unless it is the new GE AC. And freights run the Dash 9's the most. Just an observation.

Moo

[Anonymous]

I've noticed on long freights that you see a mixture of GE and EMD engines in the consist. You sometimes see a GE on the point or an EMD. Does a GE or EMD engine pull better by being on the point or does it matter at all? I assume that when trains are made up you take what you have and run with it?

Larry