B-B unit sales

[John_Perkowski]

Looking current and forward (in light of Amtrak possibly wanting new power), does GE even sell new B-B power?

Looking at their current catalog, it looks like the best they offer is a B-1/B-1 or A-1-A/A-1-A over their existing truck design on the ET44C4. (I don't know where the idler axle is).

They do offer one export locomotive B+B/B+B (a la early UP U-50s)

[NorthWest]

No. A combination of the high weights of modern freight power and railroad desires to standardize on a select few locomotive models has meant that last B-Bs were catalogued in the 1990s.

[scottychaos]

Looks like the last GE, US, Freight BB's were B40-8's in 1989.
(passenger BB's continued into the early 2000's)

https://en.wikipedia.org/wiki/GE_Dash_8-40B

Scot

[Allen Hazen]

The ET44C4's trucks are A-1-A, with the center axle unpowered. (The air cylinders and bell cranks outside the frame, which can be used to lower the weight on the idler axle so as to get more adhesive weight on the powered axles, are located in a way that suggests this, so I guess you could say that the wheel arrangement is -- almost -- visible.) EMD's bid for the four-out-of-six-axles-powered is, I think, a B1-1B unit-- don't ask me why. (Bogieman, can you explain the choice?)
Contemporary 4-axle passenger units are, it has long seemed to me, VERY heavy for passenger units, despite having a (more expensive but) lighter weight carbody design and much smaller fuel tanks than most modern freight units, so it seems reasonable that a 4-axle unit built to freight locomotive standards would be unacceptably heavy. The B40-8W (officially "Dash-8 40 B," but that style of writing model designations was not one of GE's better ideas!) was light enough to be used on the Santa Fe main line, but I think a modern version would have to be heavier: the GEVO-12 is, I think, a heavier engine than the FDL-16 (and the GEVO version used on ET4 units is probably somewhat heavier than the original version), the AC transmission is probably heavier (I think GE's AC traction motors are somewhat bigger than the DC 752 motor; internally both would have an alternator and a rectifier set and the AC locomotive adds the inverters), and the enlarged radiator and other features needed to meet Tier 4 pollution requirements are, in addition to their own weight, big enough that GE had to lengthen the locomotive platform to accommodate them.

Pity. Idler axles on a freight locomotive seem like an unfortunate design compromise, but if you want GE power for 4-axle units for fast freights (if, say, Warren Buffet gives BNSF to you, and you decide you want "Super C" timetables for intermodal trains on the Santa Fe main line), you'll have to pay extra to have them built with Genesis-style carbodies and fuel tenders. If you DO decide to spend your money this way... just a bit more and you can have them painted in Warbonnet colors!

[NorthWest]

The 290,000 lb-odd weight of the MP54AC puts it at 72,500lb, which is almost exactly the same as a 436,000lb ballasted heavy SD70AH or an ES44AH.

[Allen Hazen]

Northwest--
Thank you for the weights! The freight units are ballasted up to their very heavy weight in order to maximize adhesive weight in order to increase tractive effort at low speeds: not something that a locomotive needs if it is hauling passengers instead of coal or ore. For any given weight on an axle, damage to the track structure is greater (because of dynamic augment) at higher speeds. There may be excuses for it (e.g. the locomotive is cheaper if it is of a simple 4-axle design, and if it has much commonality with freight units), and the very heavy rail cross sections American railroads have had to use because of their heavy freight trains may permit it, but it has long seemed to me that modern American passenger locomotives are far too heavy.

[MEC407]

Looking current and forward (in light of Amtrak possibly wanting new power), does GE even sell new B-B power?

They did supply prime movers and traction motors to MotivePower, which manufactured the HSP46 4-axle passenger locomotives for MBTA Commuter Rail. The HSP46 is not a GE locomotive but it's GE-powered.

Note that MotivePower is a subsidiary of Wabtec, which is GE Transportation's soon-to-be new owner.

[bogieman]

The ET44C4's trucks are A-1-A, with the center axle unpowered. (The air cylinders and bell cranks outside the frame, which can be used to lower the weight on the idler axle so as to get more adhesive weight on the powered axles, are located in a way that suggests this, so I guess you could say that the wheel arrangement is -- almost -- visible.) EMD's bid for the four-out-of-six-axles-powered is, I think, a B1-1B unit-- don't ask me why. (Bogieman, can you explain the choice?)

The B1-1B motor arrangement has superior weight shift and lower truck assembly yaw inertia when the motors are in the same orientation as they are in all high traction trucks designs. This arrangement was first used by EMD on the GT46PAC's for India. For the SD70ACe-P4, the axle loads were adjusted so the powered axles were at 75Klbs. while the idlers were at 60K. This arrangement also allows for the end transom to be removed for weight savings since it is not supporting a motor.

Based on my experience, I don't think we'll ever see a 4 axle passenger locomotive with a 1,000 rpm engine from EMD or GE. These engines are just too heavy to package at an acceptable weight given the structural requirements today and a reasonable amount of fuel. I was working with MPI/Siemens when we bid the NJT dual modes - our proposal was for A1A bogies to meet the contract-required P1 & P2 force specifications at an axle load of 60Klbs. NJT conveniently overlooked the P1-P2 force requirements in their spec when they bought the ALP46 dual modes. These bogies were to be designed and sourced from Siemens in Graz, Austria; it was a clean, simple design with frame hung motors and disc brakes. I remain pessimistic that Amtrak would ever accept an A1A truck arrangement, I proposed one to them back in '91 when EMD was bidding the F70 but they didn't want to even discuss it then. So they are just going to have to accept 1,800 rpm engines and urea.

Dave

[MEC407]

Based on my experience, I don't think we'll ever see a 4 axle passenger locomotive with a 1,000 rpm engine from EMD or GE.

HSP46 notwithstanding...?

The HSP46 is no lightweight, but couldn't they make it considerably lighter if they used a monocoque design instead of the current frame/cowl design?

[Allen Hazen]

Thank you, Bogieman, for the explanation!
re: "when the motors are in the same orientation as they are in all high traction trucks designs" !!!! I feel really, really stupid not to have thought of this. GE's A1A truck design for the ES44C4 (and ET44C4) is based on their standard C truck, so of course the motors on the two end axles of the truck will have the same orientation -- depending on which way the train is going, both will be before their axles or both behind them. It is thus fundamentally unlike the symmetrical A1A trucks on, e.g., the Alco-GE PA or that other locomotive builder's E series, where both motors were "inboard" of their axles (so the front motor would be behind and the rear motor in front of their axles).

[bogieman]

Based on my experience, I don't think we'll ever see a 4 axle passenger locomotive with a 1,000 rpm engine from EMD or GE.

HSP46 notwithstanding...?

The HSP46 is no lightweight, but couldn't they make it considerably lighter if they used a monocoque design instead of the current frame/cowl design?

The HSP46 has a structural carbody, not a full monocoque, but fully structural nonetheless, very similar to the EMD E's and F's. A monocoque design might save 3-4,000 lbs. but with Siemens and EMD offering 125 mph locomotives at 265K and 280Klbs, respectively, with disc brakes a competitive weight is out of reach. The HSP46 is also 15'-4.5" tall, while the others meet the Amtrak 14'-8" requirement.

BTW, my last assignment while working for MPI was the truck design for the HSP46. Even with a cast steel frame, the MP1114 truck (so named because Nov. 14th was when I presented the idea for this truck to the team bidding these locos) weighs less than the fabricated truck on the P40/P42's. But it is only good for 110 mph, any faster requires disc brakes which add significant weight. The pedestal primary suspension would also have to go.

Dave

[MEC407]

Thank you for that clarification and information, greatly appreciated.

[D.Carleton]

The B1-1B motor arrangement has superior weight shift and lower truck assembly yaw inertia when the motors are in the same orientation as they are in all high traction trucks designs. This arrangement was first used by EMD on the GT46PAC's for India. For the SD70ACe-P4, the axle loads were adjusted so the powered axles were at 75Klbs. while the idlers were at 60K. This arrangement also allows for the end transom to be removed for weight savings since it is not supporting a motor.

This does raise a question since EMD's P4 foray: Why B1-1B instead of 1B-B1? Why not mimic the days of steam and early electrics where the idler axle(s) cleared the way for the traction? I'm sure there is more to this.

[bogieman]

As I stated, the B1-1B was based on weight shift between axles under high adhesion conditions. I am the one who first proposed it for the GT46PAC for that reason. Since all axles are within the confines of a rigid frame and for the P4, the axles are allowed to steer themselves, the guiding effects of a leading idler truck aren't there. If these trucks had the motor arrangement of an SD Flexicoil or similar truck, the A-1-A arrangement would have been used for the best weight shift characteristics. GE with the C4 weight changing mechanism really had no option but to go with A-1-A; If they chose to put their weight management mechanism on axle 1 or 3, it would unload the axle at the opposite end of the truck and severely overload the center axle. With the B1 arrangement, the static axle loads can be biased by choice of primary springs to make the powered axles always heavier loaded than the idler so they are less likely to loose adhesion in the first place waiting for the weight management system to react. And there is no maintenance of a crude system involving levers and chains.

[D.Carleton]

Interesting. Thank you. Was any consideration given to using the steerable truck for the C4 program? Is that even feasible?