Maximum Dynamic Braking Effort For AC4400CW Locomotives?

[PeterB]

Has anyone got a reliable reference for the maximum dynamic braking effort for AC4400CW locomotives?

So far, I can't seem to find the dynamic braking specs for the AC4400CW by searching on the web.

[mishtahshneaks]

Should be 98,000 lbf @20 MPH. Looked through my operators manual for it. Here's a page out of it if you need further confirmation.

[PeterB]

Thank you very much for this!

Much appreciated!!

[OSRFan]

If I was to put this information in to a ORTSDynamicBrakeCurve file, how would it look?

[R. Steele]

If I was to put this information in to a ORTSDynamicBrakeCurve file, how would it look?

Using Joe Realmuto's Dynamic Brake Calc. Spreadsheet .... like this:

Comment ( Open Rails Dynamic Brake Curves for AC4400CW --- Mass 417776lbs = 189.5t )
Comment ( Max Dynamic Braking Effort = 98039lbs )
Comment ( Dynamic Brake Curves courtesy of Joe Realmuto's Dynamic Brake Calc. Spreadsheet )

ORTSDynamicBrakeForceCurves (
0.10 ( 0.00 0
2.24 0
2.32 43610
6.23 43610
7.57 35884
8.92 30479
10.26 26489
11.60 23424
12.94 20996
14.29 19025
15.63 17388
16.97 16014
18.31 14839
19.66 13825
21.00 12944
22.34 12166
23.68 11476
25.03 10858
26.37 10307
27.71 9808
29.05 9355
30.40 8941
31.74 8563
33.08 8216
35.32 0 )

0.20 ( 0.00 0
2.24 0
2.41 87220
6.23 87220
7.57 71763
8.92 60958
10.26 52978
11.60 46849
12.94 41991
14.29 38046
15.63 34776
16.97 32027
18.31 29679
19.66 27650
21.00 25884
22.34 24327
23.68 22948
25.03 21716
26.37 20613
27.71 19612
29.05 18709
30.40 17882
31.74 17126
33.08 16432
35.32 0 )

0.30 ( 0.00 0
2.24 0
2.50 130830
6.23 130830
7.57 107642
8.92 91433
10.26 79467
11.60 70273
12.94 62982
14.29 57066
15.63 52164
16.97 48036
18.31 44518
19.66 41475
21.00 38824
22.34 36493
23.68 34425
25.03 32574
26.37 30920
27.71 29421
29.05 28059
30.40 26823
31.74 25688
33.08 24643
35.32 0 )

0.40 ( 0.00 0
2.24 0
2.59 174440
6.23 174440
7.57 143522
8.92 121912
10.26 105957
11.60 93697
12.94 83978
14.29 76087
15.63 69552
16.97 64050
18.31 59353
19.66 55300
21.00 51764
22.34 48655
23.68 45897
25.03 43432
26.37 41222
27.71 39224
29.05 37414
30.40 35759
31.74 34247
33.08 32859
35.32 0 )

0.50 ( 0.00 0
2.24 0
2.68 218050
6.23 218050
7.57 179401
8.92 152387
10.26 132446
11.60 117117
12.94 104969
14.29 95107
15.63 86936
16.97 80059
18.31 74192
19.66 69125
21.00 64704
22.34 60816
23.68 57369
25.03 54291
26.37 51528
27.71 49033
29.05 46769
30.40 44700
31.74 42810
33.08 41075
35.32 0 )

0.60 ( 0.00 0
2.24 0
2.77 261660
6.23 261660
7.57 215281
8.92 182866
10.26 158935
11.60 140542
12.94 125965
14.29 114128
15.63 104324
16.97 96073
18.31 89031
19.66 82950
21.00 77644
22.34 72982
23.68 68845
25.03 65149
26.37 61835
27.71 58837
29.05 56119
30.40 53641
31.74 51372
33.08 49286
35.32 0 )

0.70 ( 0.00 0
2.24 0
2.86 305270
6.23 305270
8.92 213341
10.26 185424
11.60 163966
12.94 146960
14.29 133149
15.63 121712
16.97 112082
18.31 103866
19.66 96775
21.00 90588
22.34 85143
23.68 80317
25.03 76007
26.37 72137
27.71 68645
29.05 65473
30.40 62582
31.74 59935
33.08 57502
35.32 0 )

0.80 ( 0.00 0
2.24 0
2.95 348880
6.23 348880
7.57 287039
8.92 243820
10.26 211913
11.60 187390
12.94 167951
14.29 152169
15.63 139100
16.97 128095
18.31 118705
19.66 110596
21.00 103528
22.34 97305
23.68 91789
25.03 86865
26.37 82443
27.71 78449
29.05 74824
30.40 71518
31.74 68494
33.08 65714
35.32 0 )

0.90 ( 0.00 0
2.24 0
3.04 392490
6.23 392490
7.57 322919
8.92 274295
10.26 238398
11.60 210810
12.94 188947
14.29 171190
15.63 156484
16.97 144109
18.31 133544
19.66 124421
21.00 116468
22.34 109471
23.68 103265
25.03 97723
26.37 92750
27.71 88257
29.05 84178
30.40 80459
31.74 77057
33.08 73929
35.32 0 )

1.00 ( 0.00 0
2.24 0
3.13 436100
6.23 436100
7.57 358798
8.92 304774
10.26 264887
11.60 234234
12.94 209938
14.29 190210
15.63 173872
16.97 160118
18.31 148379
19.66 138246
21.00 129408
22.34 121632
23.68 114737
25.03 108581
26.37 103056
27.71 98061
29.05 93533
30.40 89400
31.74 85619
33.08 82145
35.32 0 )
)​

[OSRFan]

Using Joe Realmuto's Dynamic Brake Calc. Spreadsheet

I have that, but am not able to figure out how to get some of the parameters. Is there a tutorial on its use.

[R. Steele]

Is there a tutorial on its use.

Not that I know of....in the thread at Elvas Tower where the Dynamic Brake Calc Spreasheet is posted there is also a pdf manual "Guideline For Setting Open Rails Braking Parameters" which may be helpful.

As you know the Dynamic Brake Calc, requires these variables to calculate the curves: Max Speed, Fading Speed, Minimum Speed, Taper Speed, Max Dynamic Brake Power and Max Dynamic Brake Effort. If you can't find these specs in a manual or design doc ( which is hard sometimes ) you can try the MSTS engine file....but many times those values are wrong in the msts eng file.
For instances -- here's a section from an AC4400 eng file for Dynamic brakes --- notice the max speed before fade out = 470 !!! (probably more like 60-70 ). MinUsableSpeed is probably close.

DynamicBrakesMinUsableSpeed( 3.5 )
DynamicBrakesMaximumEffectiveSpeed( 26 )
DynamicBrakesMaximumForce( 332.28kN )
DynamicBrakesResistorCurrentLimit ( 900 )
DynamicBrakesCutInSpeed( 6.5 )
DynamicBrakesMaxAirBrakePressure ( 50 )
DynamicBrakesFadingSpeed( 7 )
DynamicBrakesDelayTimeBeforeEngaging ( 7 )
DynamicBrakesMaximumSpeedForFadeOut ( 470 )
DynamicBrakesEffectAtMaximumFadeOut( 0 )
DynamicBrakesHigherSpeedCurveExponent( 10.4 )
DynamicBrakesLowerSpeedCurveExponent( 0.9 )
DynamicBrakesNumberOfControllerNotches( 1 )
DynamicBrakeHasAutoBailOff ( 1 )​

I was provided a "Rule of Thumb" for the following two variables you need, Max Dynamic Power and Force:

1. To find approximate Dynamic Brake power: 75% to 83% of tractive HP

2. To find approximate Dynamic Brake effort: ( + Amp Load not modeled in OR? ) -- 50% to 60% of STE

Here's a set of curves ( AC4400 ) from the spreadsheet Calc. I'm still learning this stuff also, constantly evaluating old results, and refining them as I learn more.





Hope some of this helps....if anyone has accurate Dynamic Brake specifications for specific locomotives, please post in this thread.

[OSRFan]

Thanks for that Gerry. I'll mess around with this on some of my locos and see what the results are.

I have the "Guideline For Setting Open Rails Braking Parameters" which I use frequently. Generally revamp the brake physics for everything I download according to this guide.

[pschlik]

The dynamic brake power on a 6 motor GE AC will generally be around 5200 horsepower or 6000 horsepower (higher power option comes with an extra set of grids and blowers to handle the extra heat dissipation-see the 3D model of the unit used), 3600 horsepower is quite the underestimate and won't make driving any easier! Remember, these things (and a majority of other modern units) can self-load, putting the entire power output of the main generator into the dynamic brakes, which requires dynamic brakes that can handle more power than the locomotive's rating.

[R. Steele]

Remember, these things (and a majority of other modern units) can self-load, putting the entire power output of the main generator into the dynamic brakes, which requires dynamic brakes that can handle more power than the locomotive's rating.

OR doesn't model self loading -- or amperage ----

( + Amp Load not modeled in OR? )

correct? The "rule of thumb" probably applies with a little more accuracy to older models.... anyway ... thanks for posting, accurate information is always good to have.

One other question" I've never understood what the dynamic brake "taper speed" referred to, or found it in specifications.