Charging Air With Engine Throttle In 6 + ???

[.Taurus.]

Hello

Chargin' the Air! The reverser is centered, air is set, and the throttle is in Run 6, as two GEVO's howl trying to pump the 140 car empty coal train back up after switching. Photo taken with permission. Note, before you start having kittens about fuel conservation and that the compressor does the charging without needing to notch out, I was not the engineer of this train.

This picture and its description leads me to 3 Questions:

1.)
In older engines the prime mover drives the air compresser directly via a shaft drive, right ?
Are the air compressors electrical driven in the newer engines like the GEVO ?
(A electrical driven compressor works independent from the rpm of the prime mover, if the generator produce enough electric energy with a idling prime mover ...)
How many horsepower has a electrical driven compresser commonly?!?

2.)
When engines operates in multiple, does every engine feed directly the main brake pipe
or does only the lead engine feed the brake pipe (with its own compresser and the main reservoir pipe, which itself is charged by the other engines...)

3.)
Is there a difference in "air (brake) is set" [sic] and "brake is release".
Are these two different positions of the brake value handle ?
Or describe these terms both the same brake state ?


Bye

[CN Sparky]

Can't see anything in that tiny pic (maybe I need a bigger monitor?)... but it looks like the automatic (train) brake is in release (which would make sense, charging the train). And the Independent (locomotive) brake is in apply... so the locomotive brakes are "set"..

All the GE locomotives I've been on use an electrically-driven air compressor.. it's the EMD's that use a shaft-driven one. There's even a metal plate in the GE cab saying optimum train charging is done in Idle.. so.. revving it to anything other than idle is a waste of fuel.

[John_Perkowski]

Moderator's Note:

I edited the image up from a thumbnail to something a tad larger. In a few days, I'll return it to the thumbnail.

[DutchRailnut]

and the engine is a GE(plate over Dynamic brake)) so running it in 6th notch don't help unless there are EMD units in consist.

[Jtgshu]

My RR has Motive Power switchers (MP20s I think they are officaly called, they have lots of unoffical nick names, most being bad...) with an electric air compressor, but it charges MUCH faster with the engine revving up, ive noticed in Notch 5 or 6. Why? The only thing I can think of is that the electric air compressor works better when more voltage is being produced by the loco and at idle it doesn't really make enough juice for the air compressor to work at fill tilt.......?

[DutchRailnut]

should not make difference the Compressor is fed by Inverter and no mater what engine RPM the output stays same.

[mtuandrew]

should not make difference the Compressor is fed by Inverter and no mater what engine RPM the output stays same.

The voltage stays the same, but the wattage might differ pretty greatly.

[slchub]

The GE uses an air compressor driven by an electric motor in which the motor speed and compressor loading are controlled by the excitation controller(EXC), which receives commands as far as engine speed from the cab controller(CAB), in accordance to throttle position. The proper procedure to charge the train would be to apply the drivers fully, leave the generator switch and control breaker off, reverser centered, and notch 1. Any other notch will not increase the load on the compressor. When the throttle is in notch 1, the compressor is twice the engine speed at or below 525RPM.

I prefer a quite cab as opposed to the sound of notch 3 or higher. If the BNSF has automatic downloads of the locomotive event recorder (as the UPRR does), the hogger of this train has no doubt had his manager question him/her as to why the throttle was in a setting higher than notch 2 for so long. Fuel conservation is the name of the game for the class 1's (even though the train dispatchers and/or CADIII tend to negate that).

[Jtgshu]

should not make difference the Compressor is fed by Inverter and no mater what engine RPM the output stays same.

Well thats what I thought when someone told me to rev the engine up. I even went out back and popped open the doors to make sure it was an electric compressor (it was).

Leaving it at idle it is SLLLLOOOOWWWWWW. Notch 5 or 6 it builds up several times faster than at idle. Meaning I can actually see the main res building, where as it idle its like watching a pot of water boil.......

[slchub]

But then how can you make any overtime if you notch it out?

[Jtgshu]

But then how can you make any overtime if you notch it out?

Luckily, we are still "old school" at my place.......hurry up and get the work done

[EDM5970]

Reread Dutch's first post, maybe 8 posts up. Maybe there WAS an EMD in the consist-

[CN_Hogger]

It might be different on the BNSF, but on the CN we are only allowed to go to throttle 4 if the main res. is less than 10psi above the regulating valve setting. Not to mention, most GE's i've seen say that optimum train charging is achieved in Notch 1. Even if there is an EMD in the consist, newer EMD's (SD60's and newer) rev up when the computer senses low MR pressure.