It would be interesting to see the performance difference between 8 motor diesels in the US and export versions .
By this I don't mean the double engine types like DD40X etc . More a comparison of a type with the same power assembly etc .
OvermodI am still amazed that a short little wheelbase like this improves high-speed stability (they describe easily running at 100mph). Presumably the very low polar moment made possible by centrally locating the motor facilitates it. If there is any discussion of how performance changes as the wheels wear, I didn't see it.
BDA It would be interesting to see the performance difference between 8 motor diesels in the US and export versions . By this I don't mean the double engine types like DD40X etc . More a comparison of a type with the same power assembly etc .
Upthread, I said:
‘Four-truck interurban locomotives were built until at least 1941-42, e.g. Piedmont & Northern #5600 by GE,’
That was not correct. The GE-built unit was #5611, described in Railway Age (RA) 1942 April 04. It weighed 236 000 lb. It was said that its B-B+B-B wheel arrangement was dictated by the desire to duplicate existing traction motor equipment, to maintain individual axle loading at less than 35 000 lb, and to handle 1800 ton trailing loads with a single locomotive.
I also said:
‘Illinois Terminal used B-B-B-B, with independent span bolsters. In some of these cases then span bolsters may have been associated with lateral motion trucks.’
Illinois Terminal home-built 20 of its C class from 1924 onwards. The photographic evidence indicates that these had swing bolster trucks with secondary suspension. Five of the C class were rebuilt into the D class in 1940-42.
Also, Oregon Electric home-built five four truck locomotives in the 1940-44 period. The photographic evidence suggests that these were of the articulated span bolster B-B+B-B type. They were later sold to the Chicago, North Shore & Milwaukee.
Thus there were at least 29 span bolster electric locomotives used by interurban systems, 20 non-articulated B-B-B-B and nine articulated B-B+B-B. And the build period was at least 1924 through 1944.
Evidently some of the interurban operators were of the viewpoint that for the heavier haulage jobs, eight-axle locomotives would be more economical than a pair of four-axle locomotives in MU. The span-bolster running gear enabled this concept without any loss of curving capability whilst using the same trucks and motors as for the B-B types, and keeping axle loadings within acceptable boundaries.
Regarding the solitary EMD T model, in this case the eight axle form appears to have been chosen for axle loading reasons. It was actually lighter, at 342 000 lb, than the contemporary pair of C-C transfer locomotives of similar power that the IC acquired. They weighed in at 342 000 lb (GE/IR) and 346 000 lb (Busch-Sulzer/GE). Kirkland noted that the EMC T had an axle loading of 40 500lb, as compared to 57 000 lb and 57 700 lb for the two C-C units, enabling it to negotiate more lightly laid track. A reasonable inference that the IC had some lighter track in the envisaged operating area.
Thus the reasons for the choice of span-bolster running gear were quite diverse. The UP Streamliner, VGN EL2B, GTEL4500, GE U50 and Alco C855 cases have already been covered.
The CEM 4B case derived from a request by Oferom, then the authority looking after motive power, etc., for the French overseas (Outre Mer) railway systems. Oferom wanted a single-engined locomotive of above 3000 hp, but within a 16 tonne (roundly 35 000 lb) axle loading that would be more effective and efficient than the relatively low-powered B-B units that then made up the bulk of the Outre Mer fleet. The immediately preceding Alsthom CC2400 model was a stepping stone, but its short wheelbase monomoteur C truck had turned out to have poor tracking capability. (Why that was so I have never seen – perhaps it had something to do with its relatively high centre of mass.) But that may well have created an aversion to C trucks on Oferom’s part. The axle loading constraint anyway pointed to eight axles, and the curving requirements favoured B trucks, so that the span bolster arrangement was logical, although in this case executed somewhat differently. Then concomitantly the 3B arrangement provided a six-axle locomotive without using C trucks. It may be noted though that Alsthom had used the single-frame tribo, B-B-B running gear since 1939. Within the Outre Mer and associated orbit, such had been supplied to both Madagascar and Algeria, but not elsewhere in Africa. Perhaps Oferom did not favour this type of locomotive. Note that the CEM monomoteur trucks did not have the two-speed gearing often used in French domestic practice. (But the Alsthom CC2400 C trucks did have two-speed gearing.)
That list I think closed out the “historical” use of span bolsters, which could be summarized as follows:
US interurban: At least 20 B-B-B-B and nine B-B+B-B, from 1924 (if not earlier) through 1944.
EMC T: One only B-B+B-B, 1936.
UP Streamliner: Five articulated body power cars, one of 2100 hp and four of 2400 hp in 1936. (These had just one span bolster per unit.)
VGN EL2B: Eight B-B+B-B units forming four two-unit locomotives in 1948.
GTEL4500: 26 (including prototype) B-B-B-B 1949-1954.
N&W STEL: One only C-C-C-C, 1954.
GE U50: 26 B-B-B-B 1963-64 (23 for UP, using recycled running gear, and three for SP).
Alco C855: three B-B-B-B in 1964 for UP (using recycled running gear).
CEM 4B: 27 (CFM Madagascar one, 1969; CFCO 10 1969-77; 16 RFC Cameroun 1975)
CEM 3B: 22 for RAN, Abidjan-Niger, 1970-75. (These had just one span bolster per unit, and unlike the rest of the group, six rather than eight axles.)
Forward to 1991, and the GE BB40-8M model for EFVM, Brasil. Here it would appear that the primary reason for employing eight axles was to provide a sufficient number of narrow gauge traction motors to handle the 4000 hp power output; six motors were not enough. Reduced axle loading may have been a secondary factor. Of course, the same reason had applied previously in the case of the EMD DDM40 supplied to EFVM from 1970, although in this case D trucks were used. In the GE case, given its history, it was not surprising that it chose span-bolster running gear for the BB40-8M (and subsequent BB models.) The EFVM experience with D trucks might also have been a factor.
Then, and for the same traction motor count reason, came the EMD GBB truck, which might be described as a fully integrated span bolster unit, rather than a span bolster placed over more-or-less standard B trucks. The earlier CEM unit was somewhat integrated, but in that case the B trucks were configured also for independent use.
And turning to the “fellow-travellers” with eight axles, all powered:
As previously noted, the NYC T class electrics had four truck running gear, but not of the span bolster type. Apparently NYC’s starting position was that it wanted an improved version of its S3 class 2-D-2 design, including powered pilot trucks, and with those pilot trucks spaced further away from the rigid wheelbase in order to enhance tracking and riding at higher speeds. As a better way of addressing the needs, GE split the wheelbase into two halves, articulated together at the centre, and had the superstructure ride on each half. That would have allowed more freedom in pilot truck placement, as well as significantly shortening the rigid wheelbase. Whether anyone thought of the span bolster alternative at the time is unknown. But that would have been something of a sidestep, whereas the chosen running gear was more-or-less a lineal descendant of the 2-D-2 type, via a notional B-D-B, with the D part effectively split in two. Four sub-classes were built for a total of 36 in the 1913-1926 period.
In respect of its solitary GTEL prototype of 1950, Westinghouse gave its reason for its choice of non-span bolster four truck running gear, as follows:
‘This unconventional arrangement of running-gear has advantages from the standpoint of tracking, simplicity, ease of maintenance, and light weight. The tracking stability of a truck type locomotive at high speed is dependent largely on the center-pin spacing. In the case of this locomotive, the trucks with lateral restraint are at the ends, so that the effective center-pin spacing is large. If the more conventional span bolster arrangement were used to connect the trucks together in pairs, the center-pin spacing would be much smaller.’
When Westinghouse had previously proposed this kind of running gear, in both three- and four-truck forms, for use in a standard range of electric locomotives, the PRR had expressed concern about its ability to negotiate vertical curvature without significant weight transfer. Perhaps that is why when the PRR did order its electric prototypes (originally in AC form, later changed to the AC-DC rectifier type), the E2c C-C type was included as well as the E3b B-B-B type, the latter probably being Westinghouse’ preference. (As an aside, the E2c might have been the first US domestic locomotive to be fitted with lateral motion C trucks, in this case of the single swing-bolster trimount type, probably by GSC.)
As previously mentioned, the D-D wheel arrangement was an EMD specialty, although proposed by other builders. One of the latter, not previously mentioned, was by Deutz for a 4000 hp, twin-engined diesel-hydraulic unit with axle loadings in the 23 to 30 tonne range.
Cheers,
PneudyneOne of the latter, not previously mentioned, was by Deutz for a 4000 hp, twin-engined diesel-hydraulic unit with axle loadings in the 23 to 30 tonne range.
That should have been Henschel, not Deutz, and 2 x 4000 hp, not 4000 hp.
In the case at interest though, the implied question is would the conceptual Australian B-B-B-B unit employ standard gauge or CM gauge motors?
The present locomotives in this category are the Wabtec/UGL C44 ACi and the Progress Rail GT46C-ACe
The Wabtec locomotives use the GEB 30 motor. I have no idea of its dimensions, so it may be a narrow gauge motor.
The Progress locomotives use the 1TB2622 motor which is a standard gauge motor. It was used on the SD70MAC in the USA.
The problem is solely that the permissible axle load is 22 long tons. For some reason, when the country changed to the Metric system in January 1973, anlthough lengths changed to metres and mass to tonnes, apparenly kiloNewtons became too hard, so it is still 22 long tons.
This limits a locomotive with six axles to 132 tons if it to be allowed to run at 115km/h. To increase confusion, the mass is expressed as 134 tonnes.
This is only a problem because the 7FDL16 engine is about two tonnes heavier than the 16-710G3B.
So while a GT46C ACe can carry 10000 litres of fuel within the 132 ton limit, the C44ACi can only manage 7400 litres. The desired capacity is about 12500 litres, which the Cv40-9i could carry until its motors were upgraded to the 796A1 type, which reduced the capacity to 11500 litres.
This would allow the locomotive to run from Melbourne to Brisbane without refuelling.
Does this help? Does anyone know if the GEB30 is sutable for narrow gauge?
Peter
No , it didn't limit to 11500 . Don't know why .
And no , the reason I'm asking about 8 motor performance is because I think this would be the only way to get decent locomotive performance in Australia . I doubt the Feds , States and ARTC are going to pay for US domestic standards for the rail infrastructure so we could run 5020 type units (heavier 180 tonne C44ACi) on 6 axles .
Logically the only other way to achieve this is more powered axles at the supposedly allowable 22.3 tonnes . 6 by equals 134 tonnes , 8 by equals roughly 176.5 tonnes .
Would it be too simplistic to assume that the tractive effort increases by the same 30 odd percent . If you scale the C/ES/44ACi up by 30% thats more like 1700 to 2200 tonnes on 1:40 grades .
M636C The Progress locomotives use the 1TB2622 motor which is a standard gauge motor. It was used on the SD70MAC in the USA. Does this help? Does anyone know if the GEB30 is sutable for narrow gauge? Peter
The Progress Rail 1TB2622 is a narrow gauge motor, I believe for 42" gauge. The SD70MAC motor is the 1TB2630, which fully uses the space between standard gauge wheels. The first two digits after the 1TB indicate the motor diameter, not in any particular units; the second two digits indicate the core length, again not in particular units but bigger number is longer core. The ACe motors, A3432, likewise, have numbering related to dimensions. The 1TBxxxx motors are the Siemens designation, the similar size current PR motors are A29xx.
I am quite certain based on the bogie design work I did for GE & MPI on the MBTA HSP46 locos that the GE GEB30 is a standard gauge motor similar to the GEB15 but using a smaller axle diameter.
Dave
The Progress Rail 1TB2622 is a narrow gauge motor, I believe for 42" gauge. The SD70MAC motor is the 1TB2630, which fully uses the space between standard gauge wheels.
Indeed, the GT46C ACe traction motor is the 1TB2630, not the 1TB2622 which is fitted to the earlier GT42CU AC units. I understand that the 1TB2622 was considered initially but the larger motor was actually fitted. My apologies for the error.
The GEB 30 was found in early trials in Australia to not provide the same performance as locomotives fitted with the 1TB2630 in wheelslip conditions with wet rails on a 1 in 40 (2.5%) grade. Later tests with revised wheelslip control software showed that the UGL built locomotives could match the Progress Rail locomotives.
However, Pacific National, one of the larger operators, ended up with 49 GT46C ACe units and 39 C44ACi units. Most of these are used in coal or crushed rock traffic.
BDA No , it didn't limit to 11500 . Don't know why . And no , the reason I'm asking about 8 motor performance is because I think this would be the only way to get decent locomotive performance in Australia . I doubt the Feds , States and ARTC are going to pay for US domestic standards for the rail infrastructure so we could run 5020 type units (heavier 180 tonne C44ACi) on 6 axles . Logically the only other way to achieve this is more powered axles at the supposedly allowable 22.3 tonnes . 6 by equals 134 tonnes , 8 by equals roughly 176.5 tonnes . Would it be too simplistic to assume that the tractive effort increases by the same 30 odd percent . If you scale the C/ES/44ACi up by 30% thats more like 1700 to 2200 tonnes on 1:40 grades .
I'm not sure that there is the demand for the 180 tonne locomotives. Only one operator, Aurizon, uses these units. They started their Hunter Valley coal operation with 12 4000 HP units, 5000-5012, and later purchased another 25 4400HP units 5021 - 5045. These are used on ECP fitted coal trains, usually around ninety 120 tonne hoppers with one loco on each end in wired distributed power.
There are around 190 134 tonne units of the same power which are used widely over the whole country, but the majority are used by other operators in the Hunter Valley coal traffic, usually with three units at the front of a train with fewer, sometimes 84 hoppers. These can be fuelled up to 139 tonnes on the heavy track in the coal fields. In earlier times Aurizon used one 180 tonne and one 139 tonne unit leading on the same trains as the pairs of 180 tonne units, then both leading. This seemed to work since the lighter unit was trailing and was less likely to slip. The locomotives have the same power, but the heavy units have GEB 13 motors and the lighter units have GEB30 motors.
Pacific National had been using 165 tonne DC units, GT46CWM type, but as discussed in my earlier post above, standardised on 134 tonne AC traction units which could match the heavier DC locomotives. These were usually run in threes at the head of the train, but after ECP braking became more common, one unit was moved back to the 2/3 point in the train.
The third major operator, last known as One Rail, has all ECP trains but uses three 134 tonne locomotives at the front of trains.
With only 37 units against 190, I don't think there would be the demand for 180 tonne units for use outside the Hunter. Aurizon have expanded their coal haulage fleet with more 134 tonne units, some moved from iron ore traffic in Western Australia, although this traffic has built up again more recently.
The eight axle locomotives would be more costly than either 134 tonne or 180 tonne six axle units, and not even Aurizon have purchased any 180 tonne locomotives since 2015, although they have continued to buy 134 tonne units.
Here is a description of the C44ACi locomotives:
Wayback Machine (archive.org)
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.
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