Nostalgia & History > Friday Question - What Is this Receptacle for?

On July 29, 1980, while on a business trip to Salt Lake City, I took a photo of D&RGW #5771 EMD F9A at the Rio Grande Depot.

One thing that has always intrigued me was the unit had two receptacles next to the headlight. The lower of the two receptacles is obviously a 27 Point MU Receptacle. What then is the purpose of the upper receptacle?

To help with identification, I have included a photo with an inset containing an enlargement of the receptacles. An arrow is pointing to the one in question.

Also, I noticed the same kind of receptacle on other locomotives. The insets at the top of the photo are examples.
D&RGW #5310 EMD SD9 had the same kind of receptacle on the end sill next to the 27 Point MU Receptacle. The arrow points to this receptacle that is somewhat difficult to see.
SOU #8238 EMD GP7 had the same kind of receptacle except mounted vertically instead of horizontally. The arrow points to this receptacle that is mounted across the walkway from the 27 Point MU Receptacle. Most first generation Southern units were not equipped with this type receptacle. So, I suspect it was a retrofit. Almost all second generation Southern units had this kind of receptacle. The TO Office at Barber NC back in the 1970s had a jumper cable designed for use with this receptacle. It consisted of two connectors with two insulated cables, maybe one half inch diameter, between them. The Agent said he was supposed to keep it for emergencies but did not really understand the purpose.
C&O #6013 EMD GP9 also had the same kind of receptacle identified by an arrow.

Additionally, I have seen this type receptacle on units of a number of other roads including B&LE and PC.

All definitive information will be appreciated.

For viewing purposes, a normal photo of D&RGW #5771 is also posted.

Thanks in advance.
ALLEN

This is a battery connection though the same receptacle has been used for other purposes on other roads.

Posted from iPhone

fbe Wrote:
-------------------------------------------------------
> This is a battery connection though the same
> receptacle has been used for other purposes on
> other roads.
>
> Posted from iPhone

It appears to me to be a dynamic brake field loop cable receptacle. I can't make out the small inset photos but I wonder why a locomotive would need a battery
​receptacle? Old passenger cars had a very similar looking connector and could use the batteries on an adjacent car, in the event of low or failed batteries.  
​As always, I could be wrong. Let the flames begin.

Charlie

Is this the box in a different location?


http://www.rr-fallenflags.org/cnj/cnj3677ags.jpg

Hi
That is diffently a field loop cable connecdtor for dynamic brakes ,doing it the old style way before changing to the new way of dynamic connection control
Tom Boylan

I would agree this is a field loop jumper that was required to operated dynamic brakes before rewiring the 27 point connectors to eliminate this connection. The cables had three wires that went in to the plugs. As I recall, some of SP's older Alco units (RS-11s) had this down near the trainline air brake angle cock instead of up near the 27 point MU connector. 

train544 Wrote:
-------------------------------------------------------
> Hi
> That is diffently a field loop cable connecdtor
> for dynamic brakes ,doing it the old style way
> before changing to the new way of dynamic
> connection control
> Tom Boylan

James Nelson
Thornton, CO
www.flickr.com/mojaveflyer

train544 wrote

> That is diffently ...

Definitely?

If this is receptacle is for Dynamic Brake MU, then how do you explain the receptacle on PC #2107 EMD GP20 W/O DB (ex NYC) per my attached photo? (deleted 07/17/16) NYC would have had no need for a Dynamic Brake MU receptacle on their units as they all lacked this feature.
Any explanation needs to take this into account as well as the info I provided about SOU that had practically all of its second generation units equipped with such a receptacle.
ALLEN



Edited 1 time(s). Last edit at 07/17/16 11:02 by krm152.

The receptacle on the SOU 8238 is used to hook a battery jumper cable between two units or between a locomotive and a radio control car. The battery jumper cable was very handy when trying to start a locomotive with dead batteries.

cewherry Wrote:
-------------------------------------------------------
> fbe Wrote:
> --------------------------------------------------
> -----
> > This is a battery connection though the same
> > receptacle has been used for other purposes on
> > other roads.
> >
> > Posted from iPhone
>
> It appears to me to be a dynamic brake field loop
> cable receptacle. I can't make out the small inset
> photos but I wonder why a locomotive would need a
> battery
> ​receptacle? Old passenger cars had a very
> similar looking connector and could use the
> batteries on an adjacent car, in the event of low
> or failed batteries.  
> ​As always, I could be wrong. Let the flames
> begin.

Looks like it to me too. The transition era was interesting at times, at least on B&O, because some engines had one type of control, some had the other type of control, and some had both. We had a roster under the glass on the Chief's desk that listed that characteristic as well as whether the unit had radio or not (mostly not). Between that, and a colleague leaving me almost nothing but B units whenever he could, it was possible to have a house full of power and not be able to run some of the evening's trains. Oh, yeah, and there were the ones that didn't MU at all: http://www.trainorders.com/discussion/read.php?11,1045490,1045490#1045490

TAW

The connector on SOU 8238 is a battery connector as stated in a couple of posts above. 8238 did not have dynamic brakes. The SOU units used in mid train provided power to the electronics on the radio receiver car using this connector. It could also be used to jump start a locomotive with dead batteries. The cable was only about six feet long and was easy to carry and plug in. At the terminal I worked at we also got a lot of MP and SP run through power and if one of those units had to be jumped off you got the big jumper cables that were about 100 foot long welder cables. They were heavy and it was no fun carrying them over your shoulders down the right of way.

One time we had a run through from the SP that showed up with half the units shut down to save fuel since the train didn't have much tonnage. Our dispatcher told our outbound crew to crank them all up because they would be adding tonnage. The second unit wouldn't crank so they called me. It was dark and since the dead unit's cab was facing forward I ran the cables forward to the battery switch in the lead unit which was occupied by the crew. After hooking everything I went back to the second unit, primed her up and started cranking. Just as it fired off on its own I realized there was screaming from the headend. I looked and the engineer was running down the running board and there were sparks flying out the open cab window! I quickly pulled the cables off of the battery switch of the unit I was starting and went to the lead unit. What I found was that as I had lugged the jumper cables to the locomotives one end had drug through the ballast and loosen up the clamp on the end and pulled it half off. When I started cranking the current draw started arcing, melting the wire which really got the crews attention. Nobody was hurt, all the units were now running, we had a good laugh and I carried my now wounded cables back to the enginehouse where I cut about six inches of wire off and put the clamp back on. I made a mental note that in the future, be sure and not drag the cable ends through the ballast.

Those were the good old days.
Charlie

krm152 Wrote:
-------------------------------------------------------
> If this is receptacle is for Dynamic Brake MU,
> then how do you explain the receptacle on PC #2107
> EMD GP20 W/O DB (ex NYC) per my attached photo?
> NYC would have had no need for a Dynamic Brake MU
> receptacle on their units as they all lacked this
> feature.
>
I understand your statement "....they all lacked this feature."... to imply that the NYC's order of 15 GP-20's did not come equipped with dynamic brakes. I'm not well
​acquainted with NYC locomotives, but did the NYC not have other locos that were equipped with DB's? If this is the case, is it possible NYC ordered their GP-20's equipped
​with the ability to "pass-through" the DB field-loop signal to a trailing DB equipped loco, hence the presence of the recepticals on these non-DB's units. Just wondering.

​Charlie

cewherry Wrote:
-------------------------------------------------------
> krm152 Wrote:
> --------------------------------------------------
> -----
> > If this is receptacle is for Dynamic Brake MU,
> > then how do you explain the receptacle on PC
> #2107
> > EMD GP20 W/O DB (ex NYC) per my attached photo?
> > NYC would have had no need for a Dynamic Brake
> MU
> > receptacle on their units as they all lacked
> this
> > feature.
> >
> I understand your statement "....they all lacked
> this feature."... to imply that the NYC's order of
> 15 GP-20's did not come equipped with dynamic
> brakes. I'm not well
> ​acquainted with NYC locomotives, but did the
> NYC not have other locos that were equipped with
> DB's? If this is the case, is it possible NYC
> ordered their GP-20's equipped
> ​with the ability to "pass-through" the DB
> field-loop signal to a trailing DB equipped loco,
> hence the presence of the recepticals on these
> non-DB's units. Just wondering.
>
> ​Charlie

It is possible the NYC had the receptacle on their GP20s for pass through as you mentioned.
 
Interestingly, I noticed that NYC's Passenger GP9s (no DB) were equipped with this receptacle.  This is a mystery!

Agree, the purpose of the receptacle, on practically all of Southern second generation units and some first generation units, was to provide a an expedient means for jump starting dead units.

Agree, that the original  purpose of the receptacle on the  D&RGW unit featured plus the D&RGW unit and C&O unit in the two insets of Photo 1 was to mu dynamic brakes.

The information exchange has been very educational.

ALLEN   



Edited 2 time(s). Last edit at 07/16/16 13:21 by krm152.