Powered Axle and Dynamic Brake Limits

[EMD#1]

Hello All You Fellow Railroaders!

I have a couple of questions for any engineers or conductors out there working for BNSF, CN, CP, CSX and UP.  Here on the NS we have a rulebook for Equipment Operation and Handling.

Our L-207 Rule deals with Locomotive Axle Limits Under Power and it states...

Except on designated trains, no more than the equivalent of 24 conventional (non-high adhesion) axles may be operated under power on the head end of a train.  (Designated trains are solid loaded 100 ton cars equipped with high tensile (Grade E) knuckles and couplers.)

High adhesion axles are equivalent to 1-1/3 conventional (non-high adhesion) axles.  

Alternating Current (AC) traction motor-equipped axles are equivalent to 1-1/2 conventional (non-high adhesion) axles.

(So in Laymen's terms it simply means an SD40-2 = 6 axles, SD70M-2 = 8 axles & SD70ACe = 9 axles)

Our L-210 Rule deals with the use of the Dynamic Brake and it states...

If a locomotive consist includes one or more units equipped with STANDARD dynamic brake, not more than the equivalent of 20-axles of dynamic braking may be used on the head end of a train.  If ALL UNITS in the consist are equipped with EXTENDED RANGE dynamic braking, not more than the equivalent of 18-axles of dynamic brake may be used on the head end of a train. (Exception - The equivalent of 24-axles of dynamic braking may be used for designated trains handling only loaded 100 ton cars equipped with high tensile (Grade E) knuckles and couplers.)

So here's my queston...

What are the Powered Axle and Dynamic Brake rules for your railroads compared to our rules on the NS?

Best Regards,

Tim

NS Locomotive Engineer

 

 

[BaltACD]

For Dynamic Brake calculations the following values are used

All 4-axle units except B40-8 4
B40-8-- 5
All 6-axle units except SD60/M/I, SD70M, C/CW40-8, CW44-9, and ACs-- 6
SD60/M/I, C/CW40-8, CW44-9 ES44DC-- 7
SD70AC, SD70M-- 8
SD80AC, CW44AC, CW44AH, ES44AC-- 9
SD70ACe-- 10
CW60AC-- 11

Maximum Dynamic Brake Axle Value
Do not exceed the maximum dynamic brake axle value for the locomotive consist. Those maximum values are:
•
24—when all units have alignment control couplers.
•
20—when any unit has coupler limiting blocks.
•
Do not use dynamic braking when any locomotive in the locomotive consist does not have alignment control couplers or coupler limiting blocks.

To limit draft forces, the maximum trailing tonnage for a train handled with only head-end power will be restricted as follows:
1. For loaded unit trains (coal, grain, potash, etc.) the maximum tonnage will not exceed the tonnage determined by the tonnage rating for two (2) AC4400 and one (1) C40-8 or CW40-8 locomotives.
2. For other trains, (Trains not qualifying as unit trains), the maximum tonnage will not exceed the tonnage determined by the tonnage rating for three (3) C40-8 or CW40-8 locomotives.
On grades where this tonnage limitation will be exceeded, trains will have a rear-end helper or appropriately positioned in-train helper, or the trailing tonnage must be reduced.
3. The number of powered axles in use must not exceed:
• 24—for the operating locomotives that are pulling a train or cut of cars.
• 15—when all operating locomotives are shoving a train or cut of cars totaling more than 50 cars, and every locomotive in the consist and within twenty cars of the consist are equipped with alignment control devices. If any locomotive in the consist or within twenty cars of consist is not equipped with alignment control devices, comply with Paragraph B(1) below.
• 12—on a helper locomotive when the helper locomotive is shoving a train.

When calculating powered axles, count AC locomotives as 9 axles.
When a reduction of powered axles is necessary, isolate locomotives from the rear of the consist forward.
4. ABTH rule is modified for Express Train Service only.
ABTH rule is modified for Express Trains Q090 and Q091 only, to enable the locomotive operator to use 3CW44AC locomotives or 27 powered axles.

 

[Thomas 9011]

I know for the Union pacific you can only have 8 powered locomotives to a train. You can tow more dead locomotives but no more than 8 powered.

[EMD#1]

Hi BaltACD,

I'm guessing these figures are for CSX.  Very interesting stats.  I've got one question though.  What are trains Q090 and Q091?  They must be very important trains on your railroad.  

Thanks for responding!

 

[EMD#1]

Hi Thomas 9011!

What constitutes a powered axle on UP?  Eight powered axles on the NS would be just two GP38-2s or GP40-2 locomotives.  That's not gonna cut it on a 12,000 ton freight...LOL!

Thanks for responding!

[EMD#1]

Thomas 9011...

Just found a UP Dispatcher Bulletin that was left on a run-thru that originated on the UP in Livonia, LA destined for Linwood, NC on the NS.  UP train QLINSL turns into train 172 on the NS at New Orleans.  The train shows out of Livonia with 58 loads, 14 emptys, 8,003 tons and 4,488 feet.  It shows 5 engines on the head end out of Livonia, however when I boarded it in Atlanta it only had the three assigned NS engines (not sure where the UP engines came off).

The paperwork showed the following below...

INIT  NUMBER    AC/DC  MODEL      EAPW      EADB     ACAX

NS    9432             DC       D940CW    11.5         7.9          6

NS    7570             DC       ES40DC     - - - -        - - - -        6

NS    8925             DC       D940CW    - - - -        - - - -        6

UP    2286             DC       SD60M       9.9           8.1           6

UP    9665             DC       C449W      11.5         7.9           6

TOTALS:                                                32.9        23.9         30

I'm guessing that the NS 7570 and the NS 8925 were not online and being idled with the other three being used for power and dynamic brake by the UP crew.

The paperwork  also stated that unless otherwise restricted QLINSL has the following Maximum EPA and EDBA which I'm guessing means powered and dynamic brake limits.

52 MAXIMUM EPA FRONT

28 MAXIMUM EDBA FRONT

23 MAXIMUM EPA REAR

28 MAXIMUM EDBA REAR    

If I'm understanding this right, according to the stats above then QLINSL can have 5 SD60M locos in power on the headend!  I would love to find out if these Maximum EPA and EDBA numbers are specific to certain line segments or is this a standard figure based on the type of train QLINSL is and if so if they differ for other train types.  If anyone out there in UP land knows, your help would be appreciated!

Thanks!

 

[jeffhergert]

Thomas 9011

I know for the Union pacific you can only have 8 powered locomotives to a train. You can tow more dead locomotives but no more than 8 powered.

Not quite right.  Unless specifically authorized by Train Management, you can't have more than 8 locomotives (working, isolated, or dead) in the lead consist.

Engine transfer moves (between terminals, etc) are limited to 25 locomotives.  Again unless otherwise authorized.

The UP uses equivalant powered axles (1 axle = 10000lbs of tractive effort or dynamic brake effort) for assigning power (instead of hp/ton) and for limit restrictions. System wide the power limit is 52 EPA (62 for intermodal) in the lead consist.  For dynamic braking, the limit is 28 EDBA in the lead consist. There are charts in the SSI to aid in determining EPA/EDBA for locomotives and the info appears on the crew's paperwork.  Individual subdivisions may have other requirements than whats listed in the SSI.  So you may see 8 engines up front, but most places they won't all be on-line producing power.

A few examples: most GE C44AC; C44/60AC and ES44AC have 12.1 EPA and 9.8 EDBA.  Most EMD SD9043AC have 11.6 EPA and 9.6 EDBA.  The EMD SD70ACe have 12 EPA and 10.5 EDBA.  All the numbers reflect all traction motors cut in and also not in controlled tractive effort when in DP mode.

There are also tons per axle restrictions and total tonnage restrictions for grade of coupler.  So many numbers I started carrying a calculator.

Jeff

 

[edbenton]

That is why I think IMO the GEVO AC44C4 that the BNSF ordered is going to become the new SD40-2.  Think about it can use all the power it has when it consist all the time.  Rated for 6 axles with four Traction Motors.  These engines are great for anything you throw at them as BNSF is finding out I see them on everything from GM trains to Coal trains to Intermodals.  They do not care what they are on they love to run. 

[EMD#1]

Hi Jeff!

Thanks for responding!  This is exactly what I was looking for.  Over here on the NS they limit us on the amount of power we can have on the headend to prevent knuckle and drawbar separations.  According to BaltACD it looks CSX has the same general guidelines as NS.  I'm wondering how BNSF differs and if they follow more closely to UP rules or NS and CSX?  Maybe it is an east coast vs. west coast thing as to how many units can be online at the headend due to geographic track profiles?  We tend to have a lot of grades and curves over here.  Even still...My argument is that our intermodal trains could have four high adhesion six axle DC units online at the headend and still operate safely without fear of separations.

Thanks again!

Tim

[oltmannd]

EMD#1

 Even still...My argument is that our intermodal trains could have four high adhesion six axle DC units online at the headend and still operate safely without fear of separations.

You could, but you'd have to limit the throttle notch at lower speed in order to limit the drawbar force to a safe level.  You'd have to keep it out of N8 until you go to 22 mph or so.

[Thomas 9011]

I dug out my rule book along with the special instructions for the Union pacific and found these rules....

Limit trains to eight locomotives on the lead consist or the helper consist not exceeding 42 axles of power on either consist. When 42 axles or power is exceeded on either consist isolate the excess trailing locomotives and notify the train dispatcher. limit power transfers to 25 locomotives unless train management authorizes you otherwise.

It should be noted that even though locomotives such as the SD70M have 6 axles the Union pacific counts them as equivalent to 8 axles in both power and dynamic braking. The SD9043AC is counted as 9 axles,and the SD90AC is counted as 10 axles.

The majority of the rest of the locomotives have equal power and dynamic braking with the number of axles they have; 6 axles-6 power and six dynamic braking.

I remember seeing videos of the Rio grande and the Utah railroad using as many as 12 locomotives on trains all powered. Does anyone know why and under what circumstances they would be allowed to use so many powered locomotives. Here is a youtube link to one of the videos  http://www.youtube.com/watch?v=2Za57_HF5H8

[MikeInPlano]

Thomas 9011 - is that 8 powered total, or 8 on the head end?  If UP decides to take up super-trains again (like the 17,000+ foot intermodal it ran out of Ft. Worth a while back), how would the 8 unit limit apply to those?

[Thomas 9011]

MikeInPlano

Thomas 9011 - is that 8 powered total, or 8 on the head end?  If UP decides to take up super-trains again (like the 17,000+ foot intermodal it ran out of Ft. Worth a while back), how would the 8 unit limit apply to those?

 

It would apply to 8 either all powered or 1 powered and 7 dead or any combination of dead or running.

Funny you mentioned intermodal because after reading the rule again I read "Operate double stack trains with up to 48 axles of power on the lead consist". It also says "Train management may authorize higher limits on freight trains".

Also..."When 42 axles are of power is exceeded on either consist ,isolate the excess trailing locomotives and notify the dispatcher". So according to the rules we could have 8 powered locomotives and many more dead ones in tow as long as the dispatcher is notified and the locomotives are cut out.

With helpers it says "Not more than 36 axles of power maybe used in helper consist.

 

 

 

[jeffhergert]

Thomas 9011

I dug out my rule book along with the special instructions for the Union pacific and found these rules....

Limit trains to eight locomotives on the lead consist or the helper consist not exceeding 42 axles of power on either consist. When 42 axles or power is exceeded on either consist isolate the excess trailing locomotives and notify the train dispatcher. limit power transfers to 25 locomotives unless train management authorizes you otherwise.

It should be noted that even though locomotives such as the SD70M have 6 axles the Union pacific counts them as equivalent to 8 axles in both power and dynamic braking. The SD9043AC is counted as 9 axles,and the SD90AC is counted as 10 axles.

The majority of the rest of the locomotives have equal power and dynamic braking with the number of axles they have; 6 axles-6 power and six dynamic braking.

I remember seeing videos of the Rio grande and the Utah railroad using as many as 12 locomotives on trains all powered. Does anyone know why and under what circumstances they would be allowed to use so many powered locomotives. Here is a youtube link to one of the videos  http://www.youtube.com/watch?v=2Za57_HF5H8

Your SSI sure doesn't read like the one I carry.  

Jeff

[BaltACD]

It has only been since the emergence of high horsepower/high adhesion AC engines and the concurrent appearance of high horsepower DC engines that have advanced microprocessor wheel slip control that the carriers came to realize that they could actually put more continuous tractive effort on a train than the design parameters of the cars draft gear could withstand without having some form of train handling miscue to create momentary train forces to overwhelm the car design.

Most limits are designed around the standard breaking strength of the standard knuckle used on most all cars except those normally allocated to unit train service.  Unit train service cars use a high performance knuckle that has a higher breaking strength than the standard knuckle. 

Thomas 9011

II remember seeing videos of the Rio grande and the Utah railroad using as many as 12 locomotives on trains all powered. Does anyone know why and under what circumstances they would be allowed to use so many powered locomotives. Here is a youtube link to one of the videos http://www.youtube.com/watch?v=2Za57_HF5H8

[EMD#1]

Hi Don!

Thanks for commenting on this subject.  I brought this up because I have noticed that both BNSF and UP run their trains with more power online at the headend than CSX or NS.  If they can do it safely then why can't NS?  I can see the argument for limiting powered axles on mixed freight trains where loads are dispersed throughout the train but not on intermodals.  I run both kinds of trains everyday and I am very familiar with the characteristics of each.  When it comes to additional power on the headend of intermodal trains I believe NS and CSX both choose to limit the powered axles due to fuel savings and not for maintaining safe drawbar force.  

An example:  Last night I brought down NS 213 (Rutherford, PA to Atlanta, GA intermodal) from Greenville, SC to Atlanta.  It was about 7100 ft long and a little over 5000 tons.  I had one 9-40CW and 2 ES40DC locos on the headend.  For the most part I was able to run a track speed of 60 MPH with the exception of a few long grades where my speed fell to 40 MPH.  (Running at a reduced speed over long stretches increases the actual trainsit time from origin departure to destination arrival.)  Had the train been equipped with four locos instead of three, the train could have shaved at least 2 hours if not more off its entire journey.  That may not seem like much but it could be just enough to bring more OTR trucks off the highway and that is a good thing.  Hopefully the folks calling the shots will take another look at this as I believe it is a worthy project to study.

Thanks again!

Tim

[BaltACD]

My guess - and it is only that - a guess. Is that the predecessors to NS & CSX when they laid out their routes crossing the mountains did it with much more curvature than the Western road were able to 40/50 years later.  When the Eastern carries built their lines they were cutting edge technology and like all cutting edge technologies, while they did it right enough to survive - they did not do it at the level that comes when the technology matures.  Western carriers, when they were being built had the mistakes of the Eastern carriers identified and laid out their routes to avoid those mistakes.

The Southern carriers, who built most of their trackage in the same time frame as the Western carriers did not have the benefit of finances to do the right thing.  For the most part, Southern carriers just laid tracks on top of the existing ground with all the little dips and sags without constructing cuts fills to smooth out the topography of the line.  With today's train sizes it is no unusual for a current 9000 foot train to occupy a couple of small hills and their resultant valleys - which cause slack to be running in and out throughout the train as it ascends and descends the terrain.

While all rail routes have their challenges from a operating standpoint, the Western lines did a better job of laying out their rights of way than did the Eastern & Southern carriers.

EMD#1

Hi Don!

Thanks for commenting on this subject.  I brought this up because I have noticed that both BNSF and UP run their trains with more power online at the headend than CSX or NS.  If they can do it safely then why can't NS?  I can see the argument for limiting powered axles on mixed freight trains where loads are dispersed throughout the train but not on intermodals.  I run both kinds of trains everyday and I am very familiar with the characteristics of each.  When it comes to additional power on the headend of intermodal trains I believe NS and CSX both choose to limit the powered axles due to fuel savings and not for maintaining safe drawbar force.  

Tim