GG1 Pantographs

My question concerns the correct operation of pantographs on GG1s. I have heard from two
or three sources that the PRR required enginemen to operate the GG1 with the TRAILING pantograph
raised...not the front pantograph. Yet, I have seen home movies (DVD's) showing both on operating
trains. Was there such an order, and, if so, what was the preferred pantograph? Thanks in advance.

When the weather was such that ice could form on the catenary, the front pantograph was raised to break off the ice and the rear pantograph was raised to collect power.

Chuchubob,

Thanks! That makes sense...never thought about how ice might affect an electric locomotive with
pantographs.

Electric Instructions required the use of the trailing pantograph on all locomotives. The reason being very practicle: if the forward pan was being used and was damaged in service it would trail back over the locomotive and foul/damage the rear pan. This would render the locomotive dead under the wire. However, if when using the rear pan and it fouled the catenary and became damaged or ripped off it could not damage the front pan making it possible for the engine to be continued in service.

Previous posts are correct concerning ice/sleet on the contact wire. A Train Order was issued to engineman thru normal channels signed by the Division Supt stating that both pantographs would be used in service. This order was issued during times of sleet/ice build up on the contact wire which was very damaging. Each time the pan bounced and arced although dramatic it burned the contact wire and put a pit in it causing excessive wear on pantograph shoes and in extreme cases replacement of the contact wire. A skilled engineman could do much to help alleviate this situation by using momentum and grades to keep train speed up and not use excessive amperage when starting or accelerating. Definetly one time when one did not want an engineman at the controller with an attitude of; "I don't own a bolt in her."

urrengr2003,

Thanks, great info.! I did not realize that the arcing would cause damage to the overhead wire.
I would have given anything to have seen a GG1 in action! I have always thought the sound of a
brace of E8's notching out from a start was great, but, I am told by a few that they pale in comparison
of a "G" doing her thing. Thanks again.

I'm not sure but I believe the pans were capable of being isolated so that if the front pan was up to scrape ice build-up it wouldn't draw an arc. The E-44 with both pans on the same end were problematic as to damage. Since MUs only have one pan the lead car will suffer the most damage to its shoe.

Pans on G's & P's could not be isolated from each other. Each was connected to the other with a High Voltage Buss that ran the length of the roof between pans. One tap off this buss brought high voltage thru roof straight to transformer. Design thinking was to keep high voltage (11,000v) out of locomotive as much as possible.

Pantographs each had a grounding switch that could be operated independently from the other. The purpose of this was to make the pan & the locomotive at the same potential as ground for servicing needs.

For those interested, here are the main components for a diamond shaped pantograph.

[quote="ex Budd man"]I'm not sure but I believe the pans were capable of being isolated so that if the front pan was up to scrape ice build-up it wouldn't draw an arc.[/quote]

They wouldn't need to be isolated. As long as one pantograph is in contact with the wire, there will not be any arcing. The arcing occurs when a circuit is opened, or disconnected. As long as at least one of the pantographs remained in contact with the wire, the circuit would not be opened, and there would not be any arcing.

Oddly, the RC-4 and I believe AEM-7 and ALP-44, have the ability to isolate the front pan, specifically for ice scraping purposes. Go figure.

urrengr2003 wrote:Pans on G's & P's could not be isolated from each other. Each was connected to the other with a High Voltage Buss that ran the length of the roof between pans. One tap off this buss brought high voltage thru roof straight to transformer. Design thinking was to keep high voltage (11,000v) out of locomotive as much as possible.

I believe the only GG-1 to have the power buss (which actually runs through a conduit) across the roof was the original,
# 4800. Roof shots of the subsequent, welded carbody models show no conduit with the power feeds entering the body directly under the pantographs. Some equipment which DID have roof mounted power busses were the original 1931 Reading MU's and the Great Northern Y-class electrics which also had contactors at the ends of the bodies for power transmission to other cars / locos.

http://www.steamlocomotive.com/GG1/prr4800.jpg

http://www.thebluecomet.com/pc4894RaceStphila.jpg

http://www.northeast.railfan.net/images/tr_rdg9107.jpg

http://www.northeast.railfan.net/images/gn5011.jpg

Bigt wrote:I have seen home movies (DVD's) showing both on operating
trains.

I wonder, were these home movies all shot during ice storms? Maybe there's more to this?

There was recently some fascinating information posted about GG1s in the New Haven forum by an engineer who operated them after Penn Central tookover the NYNH&H.

One issue he mentioned was the problem with GG1s getting tangled in catenary at NH interrlockings. The problem was -- as that diagram very clearly shows -- the PRR pantographs had two collectors or contact shoes. New Haven electric locomotives and MU pans only had one. The solution was to remove one shoe.

Thank you to everyone who answered my inquiry. The information provided will
allow more accurate modelling, and, has proven very interesting. Thanks again!

It's really dark, but:
This video I took of South Shore MU cars in the dead of winter shows the lead car has both pans up, while the rest only have front pan up, which is the norm. Goes to show you the practice is definitely still alive. Get a nasty snow storm and it's both pans up.
http://www.youtube.com/watch?v=bDvF2smOBAM

If you have bad eyesight, don't bother. It's really dark out.