Question on E-7, 8, 9B mu capability-

[marknycfan]

Hi all, I'm considering using an E B-unit as booster power for my proto-freelanced F-3's, GP-7's & 9's. Is there any reason mechanically this can't be done?

[icghogger]

Not from a prototypical point of view as all diesel locomotives were made to MU together. However, on the real thing, the gear ratio was different on freight units than on passenger units. E units, coupled to GPs or Fs, would experience wheel slip/spin when trying to start a heavy train. Once they got rolling, the Es would go through transistion faster and bump into the GPs, as if trying to get ahead. For that reason, we only ran E units on the head end of a mixed power consist, never in trail.

[marknycfan]

I was asking about prototype as I try to follow it as much as possible. I guess I could still run it and squint since it is my free-lanced layout.

[poweredby251]

The Milwaukee ran E-9's and FP-7's mixed together on secondary trains quite often.

[spike]

There was an article in Railroad and Railfan by Preston Cook, who worked for EMD. It was a 3 part article. The first was about the Winton powered units, then the slant nose, and lastly about the post war units. It said that the EL units were regeared, and had slightly larger wheels installed. 40" would not fit in the Blomberg A!A, but they used the biggest possible, then used a gearing which would approximate a unit with 40" wheels and 62:15 gearing.
The E units that you speak of would have likely had automatic transition. Units with manual transition would have not worked well together because they had to be shifted at different times.

[marknycfan]

But if the GP-7's are dedicated passenger units would that make them compatiable?

[lindsaya99]

The Seaboard Air Line used E7s and E8s in freight consists. According to Paul Faulk's "SAL: Motive Power and Memories" they were commonly used on Piggyback trains. There are several pics of E units (including an ABA+geep) at the head of freights in his book.

[icghogger]

Mar 15, 2010 7:34:39 GMT -5 marknycfan said:

But if the GP-7's are dedicated passenger units would that make them compatiable?

On the ICRR, the reason GP7s and GP9s were dedicated to passenger service was because they were equipped with steam generators for providing steam to the train. Because of their lower speed gearing, the company did not usually mix them with E units in an engine consist.

[oldrail]

One prototype problem with E units was they did not make automatic backward transition from parallel to series. To do this you had to reduce the throttle to idle for a moment or take the very real risk of burning up a main generator.

The minimum continuous speed for the E unit was around 26 mph, where a freight geared unit would be around 11 mph. One had to be aware of the short time ratings.

One time on the Rock Island I had a C415-E8B consist on a yard and transfer job at South Chicago, so anything is possible.

Dick

[spike]

There are several issues, most have been stated. Just because a Geep had a boiler does not mean that it was geared for passenger service. Some branch lines with passenger service just did not have high track speeds. Any hills would favor freight gearing. So would the use of the passenger Geeps or F unit in freight service, especially if it was a true dual service unit.

Some roads considered Geeps as more switching units. The cabs had one type of brake system, while the Geeps had a simpler system. These two often could not MU.

The point has already been made that the E series, and the Alco PA?PB did not have all of their weight on drivers. With the earlier wheel slip systems, a trailing A!A wheel arrangement unit could be slippery. If a consist is producing high starting effort, and a unit slips, then suddenly grabs, it often results in a broken knuckle.

There may have been times when an E was in a consist, but it was not practical, and may have been a emergency power shortage. Even if the units are all in the same consist, it does not mean that all are on line. This may happen if the E is traveling in a freight to get to the shop, or being deadheaded to a new assignment.

[Rudy Garbely]

Let's put it this way - from a mechanical point of view, there is no reason that a GP7, an F3, and an E9 can't all have traction motors with the same gearing installed and then be MU'ed together to form a functional consist. The LV, for instance, used to run their freight F3's and F7's with everything from GP9's and GP18's to Alco FA2's, RS11's, and C420's. All were geared the same (for freight service), and they all had the same MU capabilities, so there was no reason it wouldn't work.

The only factor you really need to consider is gearing, so as long as whatever locomotives you are attempting to MU can be justifiably geared the same (i.e. you wouldn't gear an SD60 for passenger service), then you can plausibly run pretty much any locomotive together (except for early Alcos and all Baldwins, which would not MU with anything except other early Alcos or other Baldwins, respectively - more on that if the interest is there for me to elaborate).

[oldrail]

Units of different gear ratios can be operated together. It's part of the engineer's job to know what he has in his consist and figure out which unit has the highest minimum continuous speed. For example:

Your consist is a RS3 geared for 70mph, E7 geared for 100, and a F3 geared for 70. Engineer digs thru his grip to get operating manuals buried under either Playboy or The Wall Street Journal and determines the minimum continuous speed for each locomotive is 10.0mph, 40mph and 14.5mph respectively. This means the slowest speed he can operate this consist in 8 throttle without short time rating (on traction motors) restrictions is 40mph.
If the F3 has manual transition it will have to be in the lead as he could not shift it with the E7 and maybe not with the RS3.

So as pointed out by others an E unit in the consist is not for drag freight operation.

Dick