Why would the Tier IV emission regs. dictate what kind of traction motors are specified on a locomotive order?
It doesn’t affect the type of traction motor. What I meant was that NS has locked in orders through the end of Tier 3 production to assure themselves of having a continuing supply of new locomotives. They believe that there will be a rush to lock in order slots as the deadline approaches and some companies may not be able to get as many locomotives as they want. What they are concerned about is that reliability of early Tier 4 locomotives will be significantly less than current models, also operating costs may be higher as a result of perhaps needing Urea aftertreatment of the exhaust, or if EGR is chosen through failures of that system. Tier 3 which becomes effective 1/1/12 is a very minor upgrade from Tier 2 so no serious problems meeting those standards is expected. Inspite of the manufacture’s assurances railroad CMOs are nervous about the ability of the builders to meet Tier 4 with locomotives that are as reliable as current models, and have reasonably similar operating costs. Especially in the first year of production. They are expecting serious teething troubles.
Leo, the last new DC powered locomotive for NS was ES40DC 7719 built in February 2008, since then (3 years) NS has taken delivery of 116 AC drive locomotives (91 ES44AC and 25 SD70ACe). NS has placed further orders for 150 more AC drive locomotives with delivery spread over three years 2012 - 2014 (50 per year). I expect that baring a big run up in rail traffic that is all the new locomotives that NS will buy in that time period. I agree it is possible that NS could still place additional orders before 2015, but I would not bet on it. BTW they bought 350 DC motored Tier 2 locomotives (220 ES40DC and 130 SD70M-2) between 1/1/02 and 2/08.
See the the pretty consistent pattern from the rates here ?
350 DC locomotives / 6 years = 58 per year, on average.
116 AC locomotives / 3 years = 39 per year (slow economy)
50 AC locomotives per year on order (I’d be surprised if there isn’t an ‘option’ to add more units to each year’s delivery.)
In short: For recent past years and for the next several years on NS, the “indicated replacement rate” of locomotives has been and apparently will continue to be all AC locomotives.
Nevertheless - and, although these figures seem low for a system of NS’ size* - for each period add to them the products of Thoroughbred Mechanical Services’ in Altoona - all DC, as far as I know - for a more complete picture of what NS is doing. See http://www.nstms.com/index.html and http://www.altoonaworks.info/ for mroe info.
*“Over 3,300 locomotives” per the TMS link above. If we assume a 30-year service life, that would mean replacing about 110 locomotives each year - about twice what NS has been doing. Will they continue to let the locomotive fleet gradually age ? Rebuild more units to keep the average age about the same ? Buy more new units ?
- Paul North.
Well, now we know part of the answer to the questions I posed above: Buy more used units ! (and perhaps rebuild them ?) Apparently word was out today that NS will buy 20 ex-C&NW/ UP SD60’s from Helm Leasing. See this webpage for a few more details: http://www.nsdash9.com/rosters/6530.html
With regard to this thread - obviously these are DC motors, which partially contradicts the recent string of NS’ all-AC new purchases . . .
- Paul North.
Without getting into the internal politics of that order, I’ll just say that as of now there is a lot of second guessing on CSX about the logic of it. Especially since all the ES44DC have now been downrated to 4000 hp. You should note that all the orders since have been for AC traction only.
AC traction is a superior technology for locomotives, pure and simple.
I look at things this way when BNSF First tried out the EVO44C4’s I knew that they were going to be a Winner. Why First off Ac Traction Motor reliability for a DC motor Price. GE figured out a way to get the power down at low speeds and the first 25 Worked BNSF reupped for 50 More. Now they went Big time for 200+ this year. I think we have the Replacement for their DC motors Look for the Dash-8s and 40-2s that they have left and Dash-9’s plus the SD-70-75’s to be hitting the bricks real soon.
One great thing about AC power is it flows from the generator through the traction motors and back through the generator in a loop. With DC it flows from the generator to the traction motors and ends there. With AC power you can stall a train at full throttle on a hill and just sit there. With DC power you would be burning up the traction motors. Burned up traction motors will be a thing of the past with AC power.
What are you talking about? - All current flows back to the starting point. The hot lead of the generator produces the ‘potential’ and it flows back to the ‘ground’ of the generator via the traction motor. There is not just one cable/wire to the traction motor(AC or DC). The copper ‘windings’ in a DC traction motor will overheat and become ‘soft’ - sooner or later they will touch the traction motor case and produce a ‘ground short’. BTW, AC traction motors are not ‘indestructible’ - They can fail from abuse…
Jim