Here is a description of the C44ACi locomotives:
This shows the a diagram of the bogies which do indeed seem to have standard gauge traction motors. The diagram of the intercooler also answers questions asked in this forum. The “variable hosepower” feature was dropped, and most locomotives were described as C44ACi although the “AC Class” locomotives were listed as “C43 ACi” on the builder’s plates.
Peter
It turns out that the span bolster idea, although not so-named at the time, was patented relatively early on in railway running gear history. It was described in US65,788 of 1867 June 18, cover page shown here:
Piedmont & Northern does appear to have been the first to apply span-bolster running gear to a locomotive, in 1917. Its #5500 was a rebuild using an express motor body, and B-B+B-B running gear. It had a total of nine span bolster locomotives, all B-B+B-B. The last, in 1949, was a major rebuild of an earlier example, so was probably tantamount to a new locomotive.
The Oregon Electric locomotives did not have articulated span bolsters, so were B-B-B-B, not B-B+B-B.
Thus, the US Interurban span-bolster electric locomotive fleet looks like:
Piedmont & Northern 9 B-B+B-B 1917-1949
Illinois Terminal 20 B-B-B-B 1924 up
Oregon Electric 5 B-B-B-B 1940-1944
Subtotals 9 B-B+B-B 1917-1949
25 B-B-B-B 1924 up
Total 34 1917-1949
Cheers,
The NYC class T electric locomotives had a B-B+B-B starting in 1913. From the drawings, I would say it had an articulated under frame as opposed to span bolsters.
From upthread:
The NYC had moved from the 1-D-1 to the 2-D-2 wheel arrangement in order to obtain adequate lateral stability. The next step was a 2-D-2 with the pilot trucks further out, in order to further improve stability with acceptable lateral railhead forces. Then it wanted powered pilot trucks, mounted even further outwards of the main frame, in what would have been a B-D-B arrangement. That would have been unwieldy. The alternative was to effectively split the running gear into two halves, articulated together, hence the resultant B-B+B-B arrangement where the outer trucks were pilots to the inners. GE patented that arrangement, US1,026,552, 1914 May 12. The pilot trucks had no lateral motion; as GE described it, each half of the running gear was like that of a 4-4-0 steam locomotive.
As far as I know, the NYC T class series was the only locomotive to use this specific running gear arrangement.
Cheers,
I am interested in the early patent for span bolsters. I recall seeing drawings and photographs of President Lincoln’s funeral train, which included two vehicles each with four trucks and I assumed that these used span bolsters, probably generally similar to those in the patent.
The C44ESACi locomotives mentioned in BDA’s early posts in this thread have finally appeared (I saw two in October). Apparently, the weight of the GEVO-12 engine, now they all use the Tier 4 crankcase, is about two tonnes heavier than the FDL-16 used in Australian locomotives to date.
This would appear to be a problem if the 134 tonne maximum gross weight remains a requirement.
Peter
You can download the complete document from here:
https://patents.google.com/patent/US65788A/en?oq=US65%2C788
Cheers,
The ES44ACi is having other dramas ATM but at least one was weighed and will be able to have 9000L of fuel to gross 134 metric tonnes .
Paperwork I’ve seen states the 10,000L will be fine for 136 tonnes , not that 1000L of diesel weighs 2000Kg , more like 750Kg .
Peter since you mentioned the Evolution V12 .
As far as I know US domestic ES/ET units have solid bolted crew cabs , with the engine/alternator bolted to a bed plate that’s isolated from the frame .
In theory , if this has been replicated on local versions you’d think the combined height of the Evo 12 and the plate plus isolators would be more than a solid mounted FDL 16 .
If the later design was height challenged all you could do is mount it lower in the frame , which allegedly has an integral fuel tank . If it’s roof is lower then capacity has to be reduced . so , 10,000 it is .
Getting back to why as the OP I asked about 8 TMs vs 6 .
With lower allowable axle loads we will always be challenged with what our AC locos can haul . The brutal truth is that the more each one can haul the fewer units are needed in many instances . Fewer units means less fuel used and running costs are important in a competitive world .
This fits in with the old adage that replacing 5 SD40s with 3 70MACs works out cheaper overall .It didn’t work out with 2 SD90Hs/AC6000s for reliability reasons , and they couldn’t pull much more than the 70MACs/AC4400s anyway .
The bottom line is that our national standard gauge units are too light and while they may have 44-4500 hp available they often can’t use it . Same deal with the 6000hp USD 90MACs and AC6000s .
Have a look at this quick dirty calc .
6000Hp divide 190T = 31.58 Hp/Tonne .
31.58 x 134T … = 4232 Hp .
So on paper we appear to be running roughly the equivalency of what USDs did with 6000Hp at their axle loads .
And because our Governments won’t spend on best practise 30/32 TAL infrastructure the only possible way here to increase unit haulage capacity is to add powered axles .
Truth be known the infrastructure providers would have fits if you turned up with a 178 tonne unit - even at 22.3 TAL - but it’s food for thought .
[quote=“BDA, post:47, topic:327051”]
Peter since you mentioned the Evolution V12 .
As far as I know US domestic ES/ET units have solid bolted crew cabs , with the engine/alternator bolted to a bed plate that’s isolated from the frame .
In theory , if this has been replicated on local versions you’d think the combined height of the Evo 12 and the plate plus isolators would be more than a solid mounted FDL 16 .
If the later design was height challenged all you could do is mount it lower in the frame , which allegedly has an integral fuel tank . If it’s roof is lower then capacity has to be reduced . so , 10,000 it is .
[/quote]
Height might not be such a problem. In the locomotives built previously, such as the FDL-engined C44ACi units, the large muffler was located above the engine inside the hood. The C44ESACi has an external muffler which forms the roof of the engine compartment. But the cab is still isolated, so there may not be the need for any special engine isolation. In my calculations I used a maximum fuel capacity of 13500 litres, which was that specified for the earliest C44ACi and a fuel specific gravity of 0.85, which I think is closer than your estimate of 0.75. Apparently 9402 and 9403 are now in service between Melbourne and Adelaide, and the ARTC TOC Waiver indicates limited areas where 115km/h will be permitted.
Peter
No , they are not in service - yet .
They hitched a ride to Sydney on NY3 and went to Melbourne the following afternoon on SM2 . And yes I read the paperwork too .
The run to Melbourne and back was for further testing and training at Dynon .
On the World-Diesel-Loco e-mail group (World-Diesel-Loco@groups.io) there was along thread about Locomotives with Span Bolster Running Gear - at https://groups.io/g/World-Diesel-Loco/topic/locomotives_with_span_bolster/103429376 - which may be useful/of interest. (You will need to join group (free) to access)
Jeremy
I did join that site but have not got to it yet .
What did get my interest was a Wiki article about the DD35/DD35A which had lots of interesting diesel loco development history and some BB info .
That eventually led me to look at Progress Loco info - and Progress/EMD is already there with a metre gauge SD70 ACE-BB .
Interesting specs to me .
2.5 feet longer than std US and still with around 15,500L fuel capacity .
I think it is 196 metric tonnes which is probably similar to USD .
It would be really interesting to see what could be done on standard gauge and squeezed into our Australian national loading gauge .
Adani in Queensland got Progress to do a Co Co GT46ACE Gen 3 on narrow 3ft 6in gauge and in their even more restrictive loading gauge . I think they gross 146 MT .
I reckon it’d be a battle to do the span bolstered BB and not be too tall for Australia . 196 MT isn’t going to happen but maybe 160-170 could be considered . Our NSW 90 Class (Canadian built SD60DC) at 167 MT was allowed in some cases , the scare factor for access providers was bridge limitations I believe .
We could get away with having less than 15,500L of fuel and maybe a tad shorter frame to suit . The next issue would be traction motors because eight 70MAC type motors are probably too heavy .
Maybe Dave could speculate on this .
EMD is building the SD70J-BB in Brazil for one of the iron ore haulers so have already built a standard gauge version of the GBB bogie. I designed that bogie to be a short height-wise as possible given the 43" dia wheels required by the AC motors, the bottom plate height is the same as an SD70ACe. It’s the wheel diameter that drives the bottom plate. On the GBB bogie, most of the span bolster is inside the underframe. But it would still be a major challenge to sink the engine/alternator low enough between the bogies to meet height clearance. Doesn’t Australia, outside of the private ore RR’s, restrict locomotive length?
Dave
Yes we do on the “National” standard gauge railways .
I’m not 100% certain but this was probably due to turn table length - I’m guessing .
Turn tables I think are being replaced over time with triangles , where I am we twist locos on triangle junctions all the time .
There could be some clearance issues on tight bends - particularly near platforms .
Are the effective bogie/truck centres markedly different on these BB units compared to Co Co units .
Another issue you mentioned is traction motor diameter and wheel size .
Do Progress/EMD have smaller diameter TMs that could be used with say 38-40 inch diameter wheels . In Queensland they run a narrow gauge GT42CUACE but I’ll have to look up what they use TM wise .
Would it be possible to lower and shorten your BB truck with more compact TMs and smaller diameter wheels . If possible this could help with overall length and height .
Just on height , it’s been suggested that a local product may have its muffler form part of the roof section above the prime mover . I assume that if true this would help in part with unit height .
Edit .
I did a quick search and the narrow gauge (3ft 6in) GT42ACE and GT42CU-ACE were quoted as having 1TB2226 and A2916-8 traction motors in the later CU version .
I have no idea if this is true .
I would like to know what other options exist within standard gauge and 38-40 inch diameter wheel limitations , but with higher torque output .
The smallest AC motors are the 1TB26XX/A29XX - they are the same stator diameter - the 1TB2226 I don’t recall - I think it should be 1TB2622. Regardless, the axle to rotor center distance is larger than the old DC motors that could use 38" wheels. 42" new wheels are as small as those motors can use unless you start limiting how much wear material is in the rims - 42" wear to 39" minimum, you could make a 40" wheel that wore to 39" but the RR’s wouldn’t like to change wheels as often as that would require. I don’t see Progress Rail investing in a new motor design unless there were forecasts to sell thousands of motors.
The GBB bogie is about as short as practical, the wheel spacing is 75-60-75". There may be a few inches to gain with smaller wheels. The 75" wheelbase of the two axle sub-bogie is driven by wheel dia, brake shoe-head-lever size, and transom width, which is already narrow.
So to ensure we’re all singing the same translation, I believe this is the design in question:
If not, I’d love to see drawings and description with the result of a couple of decades’ experience.
To me - a non-engineer - the S configuration of the span bolster is interesting.
That patent is for an updated version of the HT-BB bogie as built and tested under BN 6599, the loco with 7 axles. The GBB bogie for the SD70ACe-BB and the SD70J-BB is a completely different design incorporating all motors in line and the equalizer primary suspension. Here’s the only picture I have of the bogie assembly:
There are 8 patents issued on the GBB design, the early ones differ greatly from the final configuration. The last one issued, 9,302685, shows the bogie as built:
https://ppubs.uspto.gov/api/pdf/downloadPdf/9302685?requestToken=eyJzdWIiOiI2OWI4MzNlNi0yYzg5LTQ4YzUtODNkMi02ZDdkZGI2NzE1ODUiLCJ2ZXIiOiJlYjUyZWFiYy1kNjU1LTQ2NTgtOTQ2YS0yODFiM2U3ZDQ4ODgiLCJleHAiOjB9
Dave
The S shape of the bolster is simply to get around the traction motor air ducts up to the underframe.
Late to the party here, so I apologize. Did EMD ever do any studies to determine the potential unit reduction opportunities available by matching the 4-axle bolster trucks with a 5,000 or 6,000 hp prime mover? Seems to me there could be some scenarios where 3 to 2 unit reductions would be practicable with attendant reductions in both fleet procurement and operating costs.
I look forward to reading bogie_engineer’s thoughts on this.
Modern AC traction motors can produce considerably more than 1000hp per axle, with the important thing being cost-effective traction and spin/slip control.
Steerable trucks proved much easier to design with three powered axles – even the need for steering levers proved unnecessary (something I would not have predicted!) A span-bolstered B-B arrangement with very short wheelbase, aside from being fun to shoehorn motors into, is not going to like being made to radially steer; it’s more likely to fall back on the same theory as the Canadian short-wheelbase Flexicoil truck.
Both the 265H and the GE 7HDL suffered from severe cavitation at 6000hp, related to the geometry of the cast crankcase. I don’t expect driving the engine to still higher horsepower to improve that situation in any respect. In any case, railroads generally refused to adopt above about 4400hp per unit, and high horsepower per axle is most useful for high speed, which very little PSR doctrine supports.
