https://metrarail.com/about-metra/newsroom/metra-board-approves-locomotive-purchase?fbclid=IwAR1lhdnb5t1aAjax4d5BJwQns1tuofk6Gff125LQkBVjMqWJAT37NJttiQY
15 now, possibly up to 27 more later.
Interesting
I wonder if the Progress Rail leasors that Norfolk Southern just let go will be part of this group?
The early speculation suggests that those ex-BNSF SD70MAC's will be the starting point. I have no idea where the others will come from if Metra exercises its option.
Rebuilt freight power in suburban service is hardly a new concept. MARC, VRE, NJ Transit/Metro North and others have such locomotives on their rosters.
But they've typically have been lighter weight four axle locomotives that have been rebuilt after retirement for passenger use.
Locomotives not far removed beyond the external aesthetics from contemporary dedicated passenger locomotives that EMD was building at the same time the freight locomotive had originally been built. This on the other hand has little in common with EMD's F59PH.
I wonder how light they will be able to make them. I imagine most all of the ballast will be removed, since they won't need the same sort of tractive effort they would've needed at the head of something like a Powder River Basin coal train?
Way back in 1973 SP wanted to retire their 14 Fairbanks-Morse TrainMasters that had made up the backbone of the San Francisco Commute fleet since the late 1950s. The low cost option was to take the ten 1967-built SDP45s, of which eight were on lease to Amtrak. The first two (3200 and 3205) were modified by Sacramento shops with changes to excitation and traction motor blowers, with a "mode" switch so they could be MUed with normal power. The three GP40Ps were also set up with the Commute mode.
The other eight were modified as they came off lease. The SDP45s were used until CalTrain bought its own power in the late 1980s.
Leo_AmesI wonder how light they will be able to make them. I imagine most all of the ballast will be removed, since they won't need the same sort of tractive effort they would've needed at the head of something like a Powder River Basin coal train?
I don't know how extensive the rebuilds will be, but would it be worth the trouble to convert them to 4-motor units? That should help lighten them.
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
Will they be able to operate on the UP line or is there still bridges to be strenghten??
IMO they should remain 6 AC traction motors, That will allow for faster acceleration and better Dynamic braking!
So SD-series locomotives will return to regularly scheduled passenger service after, what, 35 years? 40?
Editor Emeritus, This Week at Amtrak
Is it correct to assume that they will shoehorn HEP on to the rear platform?
The F40Cs served long and well for approximately three decades.
There should be no reason to expect these units can't provide two decades or more of service.
http://www.railpictures.net/photo/64006/
They will need another inverter for HEP and lately they have been installing equipment like that on the fireman’s side behind the cab. There is also no need for a coast-to-coast fuel tank so look for a smaller replacement to free up space for other equipment.
(Removing mechanic’s hat and donning railfan cap.)
If indeed one or more of these are of BN heritage then certainly one should be painted in Cascade Green.
Alaska's SD70MACs have HEP, so I'm guessing these will be arranged similarly. I think that two of the axles are depowered when in HEP mode.
On ARR‘s SD70s an entire truck loses traction to provide HEP. That’s not a likely scenario for Metra. It will be interesting to see what the rebuid will entai: inverter replacement, one inverter per truck as built or one per powered axle, truck modifications, etc.
Is the expectation that they will continue to be geared for a top speed of 70 mph?
kgbw49 Is the expectation that they will continue to be geared for a top speed of 70 mph?
With a name like SD70MACH, one would expect much faster top speeds.
I enjoyed catching the BNSF C44-9Ws in Metrolink service a few years back.
blue streak 1Will they be able to operate on the UP line or is there still bridges to be strenghten??
blue streak 1IMO they should remain 6 AC traction motors, That will allow for faster acceleration and better Dynamic braking!
I would think four motors would offer better acceleration than six.
rdamon, well played, good sir! Well played indeed!
Leo Ames: No! Six motors can provide 50% faster acceleration than four.
1, Laws of physics. 2. I worked for EMD summer 1952 and my MIT SB Thesis was on diesel-electric load-regulator controls.
I can't wait to see the actual locomotive when finished.
daveklepper Leo Ames: No! Six motors can provide 50% faster acceleration than four. 1, Laws of physics. 2. I worked for EMD summer 1952 and my MIT SB Thesis was on diesel-electric load-regulator controls.
Thanks
I always thought it worked the way I thought it did (i.e., a GP9 geared the same as a SD9 and both ballasted to the same weight, would accelerate faster with all 1750 hp directed to four motors rather than spread across six). Learn something new everyday. :)
Someday I'll have to create a thread asking why AC motors offer such an improvement in adhesion over DC, since I've never understood that basic part of locomotive technology, either. I understand the other benefits, but always scratched my head about that particular part of it.
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D.Carleton If indeed one or more of these are of BN heritage then certainly one should be painted in Cascade Green.
If the illustration with the News Wire is correct, they will be getting SD70ACe radiators to allow them to meet Tier 3. (only two large cooling fans) It would be an option to fit an inverter for HEP rather than a seperate generator set. I imagine they will be getting new traction inverters anyway, and maybe new isolated cabs.
Peter
What about fuzzy dice hanging from the interior central windshield area?
Leo_Ames daveklepper Leo Ames: No! Six motors can provide 50% faster acceleration than four. 1, Laws of physics. 2. I worked for EMD summer 1952 and my MIT SB Thesis was on diesel-electric load-regulator controls. Thanks I always thought it worked the way I thought it did (i.e., a GP9 geared the same as a SD9 and both ballasted to the same weight, would accelerate faster with all 1750 hp directed to four motors rather than spread across six). Learn something new everyday. :)
I'm not an engineer, but I'm trying to think this through intuitively.
To Dave Keppler: If you feed each motor all the current it can handle, this is true, but we only have what the diesel can feed the alternator, and four motors can handle that, so we still have the same total force on the rail, assuming there is enough adhesion to handle it. By removing two motors, we make it lighter, so it should be able to accelerate faster. As I recall, the reason for the SD series is for heavy drags, since the DC motors could not handle high currents for extended periods of time. Since these units will be used in commuter service, the loads will be relatively light, and this problem does not apply to AC motors (at least not as much). Also, the power that would have gone to the motors we removed can be available for HEP, which we would need with either four or six motors.
To Leo Ames: I read your first paragraph about a dozen times, and I'm still trying to digest it, especially in light of the happy face. First of all, with the same power and the same weight, I would expect them to accelerate at the same rate. And why ballast the GP9 to the same weight? Without the extra ballast, the GP9 should have better acceleration.
Leo_AmesSomeday I'll have to create a thread asking why AC motors offer such an improvement in adhesion over DC, since I've never understood that basic part of locomotive technology, either. I understand the other benefits, but always scratched my head about that particular part of it.
Yes, do it! Since the SD70MAC's came out, I've been reading that the adhesion with AC motors is considerably better, but I don't remember seeing or hearing any explanation why. The only thing I can guess is that slip control is more precise, but that is just conjecture on my part, and would just that make that big a difference?
At low speed and starting, all, yes all, diesel-electrics are limited by motor-current only and not by diesel horsepower. That is a simple fact. AC motors can handle lots higher current, but there is still a current limitation.
I should have said, six-motored locomotives can accelerate faster up to a certain speed, beyong that it is the diesel's horsepower that controls the rate of accelertion. With typical ac-motored locomotives if used for commuter service today, the speed would be about 20 - 25 mph, depending on gearing and the number of motors.
Considering the number of stops and the short distance between stations, greater acceleration in the lower speed ranges would be a necessary capability for suburban service.
Paul of CovingtonAnd why ballast the GP9 to the same weight? Without the extra ballast, the GP9 should have better acceleration.
To make everything as equal as possible in the comparison, with the only difference being the number of axles and number of traction motors. Otherwise the added weight of the six motor unit will be a factor in its ability to accelerate.
I'll probably make a thread asking my AC traction question later today, since I'm sure we have people like M636C that will be able to explain it with ease.
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