air compressors

[wayne]

In a multiple unit consist, are the air compressors on all units operating or just the lead unit? Wayne

[adrianspeeder]

They all run, and I think they all get hooked together.

Adrianspeeder

[oltmannd]

They all run - there is a trainline wire devote to it. But, they all feed back through the lead unit and the air flow back up the consist from the trailing units is limited (I think there's even a choke in the line), so the lead unit's compressor gets more than it's share of work.

[csxengineer98]

they will an load when the main air PSI drops below the preset level...as long as the locomotive it is running... they DO NOT LOAD when the prime mover is shut down...
csx engineer

[oltmannd]

QUOTE: Originally posted by csxengineer98

they will an load when the main air PSI drops below the preset level...as long as the locomotive it is running... they DO NOT LOAD when the prime mover is shut down...
csx engineer

....and they each will unload when their own MR reaches the max PSI.

[oltmannd]

I looked it up. A locomotive can be equipped one of 3 ways, depending on customer preference:

The first way is each loco's AC runs independently on it's on compressor control switch.

The second is synchronization - if any MR in the consist drops below 130 psi, they all load and run until each reaches 140. They unload independently.

The third is dual sync - which is just like regular sync except any individual compressor will unload at 145 psi regardless of whether the trainline is still calling for it to load or not.

[arbfbe]

The mu hoses on both sides of the coupler, other than the trainline hose, is the Main Reservoir Equalizing line. (Just one hose on each side of the unit, not all three) This connects the main reservoirs on all the units to increase the capacity available for use by the engineer to charge the trainline, release the brakes on the train and maintain the pressure on the trainline. Yes, there are chokes and one way check valves involved but the result is all the reservoirs on the units act as one. Each unit's compressor commonly is set up to pump air into that locomotive's main #1 reservoir to keep it charged to 120 to 140 psi. The reservoirs of units in the consist that might have a malfunctioning compressor are kept charged by the other units in the consist.