I have noticed when a large number of engines (say a dozen) are being moved as part of a larger train they are usually on and idling. Other times they appear to be on line and pulling. This doesn’t seem to make obvious sense as their additional power is certainly not needed, nor can it even be fully used. Why burn that extra fuel just to be towed along? Thanks.
Same reason we leave them idling when standing. When it’s cold it keeps the water plugs from dumping the water in the engine. Also helps to have the extra air compressors running to charge the trainline quicker after stopping.
depending on the time of year… they are left running but not online to keep them from freezing up…in warm and cold weather…the batteries might be low and if the unit is shut down…it might not be able to be restarted without haveing to jump start it… and also there are restrictions as part of the opporating rules that state now many axles you may have in power/dynmaic brake… to comply with the rules some of the engins in a large consist cant be online and have to be isolated… also keep in mind that just becouse a locomotive has 6 axles under it donst mean it is a 6 axle locomotive as far as figering out the number of axles alowed on line… each class of locomotive is given an axle value based on the amout of tractive effort it can generate… for example a AC locomotive such as a sd-70mac might only have 6 axles under it but if memory serves me correct…on csx they are valued as haveing 9 axles… so when an engineer is figering out how many axles he can have online…he has to look at the whole consist and total up the axle vaules for all the engines… and if the total number is more then he is alowed…he has to isolate some units…
csx engineer
Thanks guys. Makes more sense now.
If you do have to jump start due to a low battery is it a big deal with the AAA ([:P]) or can you just connect to another engine through the regular cables and do a normal start?
They are beefy cables. I think Ed has a good story bout that…
Adrianspeeder
there are jumper cables that are just like the kind you use to jump you car…but alot longer and the cables are thicker… you put the aligator clamps on the battery knife switch of one unit that is good…the the knife switch of a unit that needs the jump…then go fire that puppy up
csx engineer
That’s just like we did it down on the farm.[^] That cable set must weigh a bunch to drag around.
Can a cluster of dead engines (not running) be towed OK on a warm day as part of a regular consist, just other boxcars, or does their great weight require the additional braking air etc which their running engines can provide? [%-)]
(The reason I ask is that I’ve seen heavy old antique steam engines moved slowly, but placed between two big diesel engines and some extra coal cars just for the extra braking control they provide.)
i should have clairifed that axle value thing a little… so i will do that now… if the unit is dead…as in dead in tow and cant be started…or is shoped and cant be used for power…the unit dosnt count for firgering axle vaules numbers… only units that have the potental to be used as power are figreded into this…
now to awnser your question… if they are dead and cant be used for power becouse of being shops or cant be started…or if the weather is warm and the unit isnt needed for power to pull the train and is shut down to save fuel… it is considered as far as train handeling goes just another car in the train… and depending on how the air brakes are set up on each unit being towed…they will as far as brakeing goes…respond as a car…or as part of the engin consist…
csx engineer
Thank you. Very helpful posts.
If you lose power on an active unit while enroute will you also lose the braking power (both dynamic and static) from that unit? [C):-)]
dynmaic yes… air no…
csx engineer
That’s very interesting csxengineer98. [;)] As an Electrical Engineering exercise it would seem to be a simple matter of rewiring (by relays, or whatever) to maintain the dynamic braking asset in a towed unit. Hmmm…
It’s been done , field loop dynamics worked on trailing units regardless if they were running or not . Problem was the connectors blowing to bits between the power and contactors getting hung up .
Can you clarify, what’s the reason axles are being counted. I understand there may be a need to limit total pulling power for a train (to avoid broken knucke) but why base it in axle count especially this weird thing where 6-axle is considered 9-axle? Axel count on a locomotive does not indicate its pulling power.
On our railroad braking effort is limited to 200.000 lbs. On older conventional locomotives, each axle can produce 10.000 lbs of effort. A six axle SD40-2 or a C-30-7 can produce 60.000 lbs of braking effort.
The next step was the higher capacity dynamics like the GP50 and the dash 8 locomotives. These engines can produce 15,000 lbs per axle . A GP50 can produce the same effort as an SD40 so it counts as a six axle locomotive. The AC l
the reason for limiting axles in power and dymanic brake is so you dont put to much buff or draft forces on the draft gear and knuckes…to many axles on line when starting out can either rip the drawhead or knuckel off the car…or worse yet string line the train and derail it…and if to many axles are online for dynmaic brakeing…you can cuase to much buff forces on the cars and buckle the train and derail…
also it is based on axle counts becouse ea
Hello everyone on BNSF according to the air brake train handleing rule book on any train I can have up to 42 rated powered axles, on a total intermodal train I can have 48 rated powered axles. The dynamic requirements are no more than 28 rated dynamic brake axles due to high buff force that can be created when the train gets around 10mph. When I figure how many dynamic brake axles I will use I take the tonnage of the train and divide by the axles of dynamic I have for my use, on the newer and some older units I can cut out the dynamics on that unit not to exceede 400 tons per dynamic brake axle.
Rodney
Rodney
Not wanting to question your word, But in the way you state this is a little high for powered axels. Now I am allowed 24 powered axels on line ( 32 if solid bulk train) and for the sake of doing alot of math we have a rule of no more than 18 axels of dynamic. the way I see it you are allowed 6 dash-9 on line ( 8 x 6 = 48 and 8x5 = 40 ) For the ones not knowing how we figure powered axels the NS does it like this. A dash 9 axel is equal to a 1 1/3 power so a 6axel high adheshion unit ( these are sd 50,60,70,80,90 ge dash 8,9 the ac units and so on.) and then add the 1/3 up, so you have 3 axel truck in front and 3 axel in back. front truck 3 +1/3 + 1/3 + 1/3 = 3/3 or to me 1 total of 4 same in rear so 4+4=8 this is how you get 8 axels of power out of 6 axels. and then for the ac traction motor is 9 or 1 1/2 axels or 4 1/2 per truck and take that and the rear 4 1/2 + 4 1/2 = 9. now back to rodney how is yours figured so i can be on the same page ?
Colleagues -
Actually, the reason for the axle limitation is not limited to in train forces, although that is certainly a very valid reason. I can remember well when the NS adopted the axle limitation rule. At the time we had an incident where a train was being shoved on to a siding through a control point. There were six large units on the head end of the 130 car mixed freight train (GE Dash9s that rate as 9 axles) and all were on line. As they shoved through the wye at the control point the forces exerted on the rail caused the track structure to fail in a spectacular way resulting in several cars leaving the track in a pile.
The next day we had a new order limiting the number of axles online and instructing how to account for the axle counts.
Oh, and on a sad note, although there were no injuries on the scene, a young contractor lost his life while scrapping one of the boxcars involved a few days later when he apparently cut the wrong part and a boxcar door fell free directly onto the contractor killing him instantly.
LC