curious about car numbering

[orangeline]

Yesterday I returned home from Rockville, MD and had the chance to ride MetroRail from Shady Grove to National Airport. I very much enjoy riding Metro and do it whenever I can. On the Red Line train I happened to be sitting in car 1234 and noticed a small "AC" following the number. This was on the door to the operator's cab. After getting off at Gallery Place I saw a small "AC" below the number on the outside of the car beneath the operator's window. I went to the lower level and took a Yellow Line train to National Airport. That car's number was in the 3000 series and there was no "AC" following it. My question is: What does "AC" stand for?

[starionwolf]

I think AC stands for Air Condition, automated control or auto-something cabinate. I don't know why some cars have AC cabins while others do. I don't think the first and last cars have AC cabins, but only cars in the middle. I sat in an orange line train that had AC cabins. I think only the older cars have AC cabinets, but I'm not sure. I forgot the car number. Sorry!

I haven't seen the AC on the operator's cab door, but I have seen it on the other doors.

I'll ask around.

[Robert Paniagua]

Actually, the "AC" is only found on the Rohr (Type 1) cars. The AC does not appear on any other car, not even the Type 5 newest rolling stock.

AC could also stand for Alternating Current.

[starionwolf]

Actually, the "AC" is only found on the Rohr (Type 1) cars. The AC does not appear on any other car, not even the Type 5 newest rolling stock.

AC could also stand for Alternating Current.

I talked someone who knows a little about the metro trains. From what I understand, AC has something to do with the Alternating Current motors. Reahabbed cars have the words "AC" so that rail workers can identify them. Apparently, the older trains have DC motors before the were rehabilitated.

The 5000 series cars have new AC traction motors. I'm not 100% sure though.

Hope this helps.

[starionwolf]

This page has a photo and some informtation:
http://transit.schuminweb.com/rail/wash ... sp?key=494

[DCmetrogreen]

It stands for Alternating Current as the original Rohrs had DC motors and were later overhauled with AC motors

[Sand Box John]

The AC under the car number means AC traction propulsion system.

The only cars that WMATA has that were delivered from the manufacture with AC traction propulsion were and are the 5000 series delivered from the joint venture of Construcciones y Auxiliar de Ferrocarriles/ AAI Corporation (CAF/AAI) and the 6000 series cars from Alstom that are now going through acceptance testing.

The 4000 series Breda’s (Breda Costruzioni Ferroviarie Ansaldobreda S.P.A.) were from the option extension order on the original Breda car procurement contract.

Both the 3000 and 4000 series Breda car were delivered from the manufacture with DC traction propulsion chopper controllers. The 2000 series were delivered from the manufacture with DC traction propulsion cam controllers.

The 1000 series Rohr cars were delivered from the manufacture with DC traction propulsion cam controllers.

All of the 1000 series Rohr cars were rehabilitated in the mid 1990s and had their propulsion systems upgraded to AC traction.

The Breda are now in the process of being rotated out for rehabilitation and propulsion system upgraded to AC traction.

When the rehabilitation of all of the Breda car is complete WMATA will have an all AC traction propulsion system fleet.