[Coolhand101]

Hi

When using trainsets with multiple compressors, i've notice that all will work simultaneously or only the first one will work, once the main res air pressure(100PSI) has dropped below the recharge pressure(90PSI).

From what i can see, if 'air single pipe' is used in the engine files, the first compressor will kick in at the recharge figure, but the remaining compressors will not recharge because the main res is still at the max pressure.

When using 'air twin pipe', all compressors will work, as the engines main res falls below the recharge figure.

Is this correct ?

Thanks

[Coolhand101]

Coolhand101, on 07 November 2015 - 03:05 AM, said:

Hi

When using trainsets with multiple compressors, i've notice that all will work simultaneously or only the first one will work, once the main res air pressure(100PSI) has dropped below the recharge pressure(90PSI).

From what i can see, if 'air single pipe' is used in the engine files, the first compressor will kick in at the recharge figure, but the remaining compressors will not recharge because the main res is still at the max pressure.

When using 'air twin pipe', all compressors will work, as the engines main res falls below the recharge figure.

Is this correct ?

Thanks

On further testing this matter with "air_single_pipe" engines.

If multiple engines are at the front of the consist, the independent compressors will work.

If multiple engines are in the front, middle and rear of a consist, the front engine compressor will work, but the middle and rear engine independent compressor will not work.

So the engines have to be behind one another in front of a consist for the independent compressors to work.

With "air_twin_pipe" the engines can be anywhere in a consist and still have working independent compressors.

This could be a bug with "air_single_pipe" engines as the compressors should still work regardless where the engines are in a consist.

Can anyone please confirm this!

Also, is it possible to disable the compressor for the front engine ( front EMU/DMU trailer coach but drivable )

Thanks

[sim-al2]

Coolhand101, on 07 November 2015 - 11:52 AM, said:

This could be a bug with "air_single_pipe" engines as the compressors should still work regardless where the engines are in a consist.

I'm fairly sure it's supposed to be this way, the normal Westinghouse system only feeds from the air valve in the controlling locomotive, but most MU systems allow for main reservoir connections between units to effectively increase the size and compressor capacity of that reservoir. Since non-locomotives rarely feature these connections, barring certain DPU technologies only the units MUed with the controlling locomotive will have their reservoirs contributing.

Since the Open Rails twin pipe model supplies air to the supply pipe at main reservoir pressure, it acts as a direct connection through the train, similar to having those MU connections. (Some systems run the supply pipe at reduced pressure from the reservoir, but still above brake pipe pressure. For example, 10 bar MR, 6 bar supply pipe, and 5 bar brake pipe.)

[Coolhand101]

sim-al2, on 07 November 2015 - 05:57 PM, said:

I'm fairly sure it's supposed to be this way, the normal Westinghouse system only feeds from the air valve in the controlling locomotive, but most MU systems allow for main reservoir connections between units to effectively increase the size and compressor capacity of that reservoir. Since non-locomotives rarely feature these connections, barring certain DPU technologies only the units MUed with the controlling locomotive will have their reservoirs contributing.

Since the Open Rails twin pipe model supplies air to the supply pipe at main reservoir pressure, it acts as a direct connection through the train, similar to having those MU connections. (Some systems run the supply pipe at reduced pressure from the reservoir, but still above brake pipe pressure. For example, 10 bar MR, 6 bar supply pipe, and 5 bar brake pipe.)

Seeing this from a different perspective, i can now see the logic on this matter.

Many thanks

[Csantucci]

This discussion is a bit a sequel of this one http://www.elvastowe...er-train-locos/ , where some concepts were already discussed.

[Coolhand101]

Csantucci, on 09 November 2015 - 08:17 AM, said:

This discussion is a bit a sequel of this one http://www.elvastowe...er-train-locos/ , where some concepts were already discussed.

Reading that thread, concurs with my problem with independent compressors in the middle or rear of a consist when using "air single pipe".
Is this matter still ongoing ?

Thanks

[Csantucci]

Yes, but it's not a bug, it's a feature accordingly to the experts (I'm not one on this field).

[railguy]

While the controlling locomotive engineer (almost always the lead locomotive, since the lead locomotive engineer can see the track ahead) controls the brakes via his brake stand, the trailing units in an MU consist should contribute air to recharge the brakes when a release is made. So, the compressors should run AND the recharge rate should be faster with multiple engines. Also, if the locomotive's air compressor is mechanically driven (most EMD's are, later model GE's have an electric motor driven compressor), throttling the engine up should also increase the charge rate. In real world railroading, I've regularly seen engineers throttle his stationary locomotives up to Run2 or Run3 to hasten the recharge rate for a long train.

Now, as to DPU, they are almost always set up that their brake systems will react to the controlling locomotive's actions. An advantage there is that, for example, when the engineer makes a brake set, the DPU's will do the same, effectively shortening the time that the brake pipe pressure reduction "signal" takes to reach the rear of the train. The DPU locomotives also will contribute their air to the recharge of the brake system when a release is made. All of these features should be modeled into OR. While DPU's are fairly uncommon in some parts of the world, in North America they are pretty much now standard operating procedure.

A copy of the GE ES44DC operating manual can be found here: bartfk.cba.pl/gfx/opm/SP-ES44DC-GE.pdf
It includes an entire section on setting up DPU operation, as well as a lengthy discussion about air brakes.