As I understand it, when Victorian Railways (VR) ordered the Clyde G8, it was at the 43’0” standard length. (VR Newsletter 1954 October). Presumably it then agreed to the 44’6” length requested by QR for the G12. But then subsequent deliveries (of the G8B) were shortened to 40’8”. Clyde was first to build the GR12 model, for QR (1450 class). Its version had 12’6” wheelbase trucks and was 49’2” over end frames. The EMD version had 12’2” w
As I understand it, when Victorian Railways (VR) ordered the Clyde G8, it was at the 43’0” standard length. (VR Newsletter 1954 October). Presumably it then agreed to the 44’6” length requested by QR for the G12.
The drawing I mentioned of a scaled down GP appears on page 9 of Diesel Railway Traction for January 1956, with an article reporting the delivery of the T class to Victorian Railways. The only dimensions are length, 43 feet over headstocks and bogie centres, 25 feet.
While those dimensions match the EMD standard G8, the loco illustrated is entirely different. Small platforms extend past the headstocks at each end with railings. The vee shaped ends allowed more room on the end walkways particularly just above the steps. The plating on the frame sides has seven louvred access panels, like those seen on SD7s. The fuel tanks and the battery boxes are arranged differently, and the roof grille over the radiators extends down the body sides requiring the hand rail to be lowered beside the radiators. The drawing shows the outline of full VR lining.
A photo of T324 appears in the article, and nobody appears to have noticed that it looks nothing like the drawing.
It is possible that the longer frame was offered by Clyde as providing at least one cross walkway, which the revised EMD design eliminated.
Interestingly, the shorter G8B locomotives reverted to the Vee shaped hood ends, but without walkways at either end .
Peter
I had also noticed the anomaly in the DRT article on the VR T class G8. There was another like case with the NSWGR 48 class Alco DL531, in the 1961 August issue, pp.326,327. The accompanying drawing showed the standard (Alco US) version, not the Australian version.
Looking at the equipment layout drawings for the EMD and Clyde versions of the G12, in the latter, the whole air compressor/generator/engine/fan drive assembly appears to have been moved backwards somewhat, as might be expected to retain weight balance. But the (overhead) radiator looks as if it had retained more-or-less its original position with respect to the front of the locomotive, so that it then had a forward offset relative to the fan. That may have been done to allow enough room for a rear platform.
Cheers,
Returning to the span bolster case, we may look for GE’s reason for using that type of running gear for the GTEL4500.
Three paragraphs from AIEE paper 50-77 (1) are pertinent:
‘The Alco-GE gas-turbine electric locomotive is designed for freight service. It is an 8-axle 8-motor B-B-B-B locomotive, weighing 253 tons (average) and rated at 4,500 horsepower for traction (at 80 degrees Fahrenheit and 1,500-feet elevation). The locomotive is 83-feet 7**½-inches long, and 14-feet 3-inches high over the roof sheets. It will negotiate curves of 288-feet radius.’
‘The general design, especially the power rating and weight of the locomotive, was developed from analyses of freight and passenger locomotives in use in this country in 1941 and 1946. These analyses indicated that about 75 per cent of the freight locomotives were in the 4,000-to-5,000-horsepower range and had approximately 500,000 pounds on drivers. The studies also showed that approximately 90 per cent of the total locomotives in use in road service handled freight. Consequently, it was decided to concentrate on designing a freight locomotive in this range of power and weight. To be attractive and profitable to the railroads, this locomotive must show a low initial investment, low fuel cost, and low maintenance cost.’
The trucks are of the conventional 2-axle swing-bolster type. Each pair of trucks is connected by a span bolster which, in addition to spanning the two trucks and supporting the locomotive cab, also acts as a traction-motor air duct. This arrangement gives a high degree of flexibility on curves. It also has sufficient vertical flexibility to give satisfactory riding qualities even on comparatively rough track. Resonant vibration between the truck equalizers and the swing bolsters was encountered at low speeds. Damping means were provided in the spring system and no further trouble has been encountered.’
Thus we may deduce that GE opted to provide on eight axles a GTEL “equivalent” to a typical three-unit diesel-electric freight locomotive, which had twelve axles. As an aside, the capacity of the then relatively new GE761 traction motor facilitated this. And with eight axles chosen, the four truck span-bolster arrangement presented itself as the optimum choice. Inter alia, it did allow the use of standard two-axle trucks from diesel-electric practice.
Fairly recently, GE had used the span bolster form, albeit articulated, for the VGN EL2B motor generator electric locomotive. This was designed at the same time as the GN W1 class. In both cases the starting point was the GE746 traction motor, from which the respective axle counts, and then the wheel arrangements were derived. From ASME paper 49-SA-7 (2):
‘A study of the service requirements and the performance of the existing motive power indicated that a locomotive carrying approximately a million pounds on drivers would be required. Since the top speed involved (50 mph) was moderate, it was decided that all weight would be on drivers and no special guiding axle would be required.’
‘The selection of an eight-axle running gear for each of the two cabs narrowed down to two designs, a B-D-B arrangement employing a main frame, integral with the cab structure, and two two-axle swivel truck, or a B-B+B-B arrangement, employing four identical two-axle swivel trucks.
‘The second arrangement was selected in the interests of easy maintenance, interchangeability. of trucks, and over-all superior flexibility of operation. The resulting locomotive nomenclature of this arrangement of running gear is 2 (B-B+B-B), and each of the two units composing the locomotive., for all practical purposes, a duplicate of the other.’
In this case the moderate top speed allowed the use of both articulation between the span bolsters (without any stability aids) and rigid bolster trucks. GE’s work on the EL2B case evidently informed its choice for the GTEL4500. In the latter case the locomotive length would anyway have made articulation of the span bolsters more difficult, but GE may have also decided that it was not appropriate.
Not covered in any of the references that I have seen is the choice to mount the couplers on the span bolster outer ends rather than the main frame ends. This might have been simply a dimensional issue in respect of coupler overthrow on curves. The span bolster centres were at 41’6” against an overall length of 83’7½”, so the former was not a large fraction of the latter. Coupler overthrow in a given curve is a function of both truck centres and overhang, increasing with both but also increasing with the overhang-to-truck centres ratio. (There is probably a standard formula for this.) So perhaps keeping the overthrow within bounds was the reason for GE’s choice. It may be noted that the later EMD DDA40X case showed that with a very long locomotive, the couplers could still be mounted on the frame ends provided that the overhang was not excessive.
But there might also have been a structural element here as well. The GTEL4500 main frame was effectively a more-or-less full-width and very deep box section that formed the fuel tank, upon which the superstructure and equipment was mounted. Possibly it was thought that it was preferable to have this structure carry the buff and drag forces only between the span bolster pivots, and not at the outer ends.
As a possible precedent, one may also look at the Illinois Central Busch-Sulzer prototype #9201 of 1936, whose mechanical parts were designed by GE, who said (3):
‘By taking advantage of the maximum bridge loading permitted by the railroad, it was possible to limit the number of axles to six and thereby design a simple running gear consisting of two three-axle, non-articulated swivel trucks upon which the cab is mounted.
‘The problem of holding the total weight within limits, permitting the use of six axles, was a serious one, without resorting to extensive use of special material in the cab. However, by putting the draft gear on the trucks, no part of the platform carries more than one-half of the drawbar pull; and by using a heavy centerplate, a suitable design was obtained.’
Perhaps the same thinking applied to the GTEL4500.
The running gear decisions made in respect of the GTEL4500 then informed the GE U50 and the Alco C855. Whether GE might have done differently in a “clean sheet” situation is unknown. But when it came to the BB40, it opted to mount the couplers on the frame ends, and not on the span bolsters. In part this may have been because the frame (derived from the C40?) was designed this way, and in part because the specific dimensions allowed it.
As previously mentioned, the CEM 4B design of 1969 had its couplers mounted on the frame ends. It was 62’8” long over couplers, 59’1” over end frames, with span bolster centres at 35’1”. Evidently the coupler overthrow was not excessive, even though the locomotive was intended to negotiate 50 metre (164 ft) radius curves. It was not though the longest CMT (Cape/metre/three foot) gauge single-frame locomotive extant. One candidate for that at the time would have been the 1959 Ghana Railways 1401 class C-C, Henschel/EMD model TT12, 64’4” over couplers with 35’6” truck centres.
(1) AIEE 50-77 ‘The Alco-GE 4,500-Horsepower Gas-Turbine Electric Locomotive’ by A.H. Morey (GE), 1950 January
(2) ASME 49-SA-7 ‘’Motor-Generator Locomotives, Their Design and Operating Characteristics’ by J.C. Fox (VGN), J.F.N. Gaynor (GN) & F.D. Gowans (GE), 1949 June.
(3) Railway Mechanical Engineer 1963 September, p.383ff, ‘Busch-Sulzer 2,000-Hp. Switcher.’
Cheers,
Thus we may deduce that GE opted to provide on eight axles a GTEL “equivalent” to a typical three-unit diesel-electric freight locomotive, which had twelve axles. As an aside, the capacity of the then relatively new GE761 traction motor facilitated this.
I assume you mean the GE 752 motor, which indeed remained in production for new GE locomotives up until the ES 44DC and is probably still available. The GE 761 is a metre gauge motor, which while extremely successful and still in wide use would not be useful for USA Domestic situations.
Peter
As previously mentioned, the CEM 4B design of 1969 had its couplers mounted on the frame ends. It was 62’8” long over couplers, 59’1” over end frames, with span bolster centres at 35’1”. Evidently the coupler overthrow was not excessive, even though the locomotive was intended to negotiate 50 metre (164 ft) radius curves. It was not though the longest CMT (Cape/metre/three foot) gauge single-frame locomotive extant. One candidate for that at the time would have been the 1959 Ghana Railways 1401 class C-C, Henschel/EMD model TT12, 64’4” over couplers with 35’6” truck centres.
The TT12 was a double ended verandah cab unit, and the rounded EMD noses would have reduced the clearance problem compared to the French locomotives with straight boxcab bodies.
Thanks for spotting that error. Yes I did mean the GE752, not the GE761. Senior moment, I think.
Cheers,
Earlier in this thread Pneudyne introduced the French built B’B’B’B’ locomotives with monomoteur bogies. Today I found a video giving very good detail of the BB16500 class and its monomoteur bogies. In particular, it shows the procss for manually changing the gear ratio between passenger and goods traffic.
La passion des trains - La grande famille des BB (n°36) - YouTube
The section of the video starts at 8min 17 sec and is entitled “Light Cavalry”. Sadly the commentary is in French but there are closed captions available, also in French, but these should help anyone with a basic understanding of French.
However the use of a large scale model with a perspex gearcase and detailed video of the assembly of a bogie show clearly the principles and construction of the bogie. The assembly of the prototype three axle monomoteur bogie is shown at the end of this section of the video.
The rest of the video is also interesting but covers other aspects of B’B’ locomotives, including an experimental locomotive with synchronous AC motors, something the French took more seriously than others.
Peter
Amusingly the subtitles refer to “B-B” locomotives consistently as ‘bebes’. I don’t know if this is the same happy thing as ‘deesse’ Citroens… but I’ll take it.
Amusingly – I first came across this truck in the Ransome-Wallis Encyclopedia of World Railway Locomotives… where I learned that the gear ratio was adjustable by the engineman. I later ‘learned’ that the conversion could only be done in the shop, and believed that for many years. The rocker approach to a common central motor pinion – combined with clear film describing the quick-change – establishes pretty conclusively that my original understanding was right.
I 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.
Having observed the simple and rapid gear change on the model bogie, I was a little surprised at the apparent complexity of the manual operation. However, after a little thought, I realised that the change had to occur on both trucks simultaneously, so the mechanism had to stretch the length of the locomotive, changing both pinions at the same time…
Peter
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 .
The short wheelbase B truck goes back to the work done by Jacquemin for the BB9003/4 prototypes in the early 1950s. In fact, the basics, with an equation, were covered in Ransome Wallis (pp.185,186 in the Hawthorn first edition). That chapter of the book was written by Haut, who could be somewhat variable, but in this case I think he pretty much quoted from the SNCF source.
Cheers,
I haven’t seen any comparative performance data for US domestic C-C prototypes and their corresponding CM-gauge export B-B-B-B derivatives, although I imagine that it does exist somewhere.
I should estimate that over much of the speed range, their tractive effort curves would be fairly close. At the low-speed end, there might be differences due to difference in adhesive weights. At the high speed end, possibly unloading would set in a little earlier in the eight motor case. Although with high capacity alternators, that seems unlikely.
I suppose the similarity or otherwise of the curves also depends upon the relative capacities of the standard gauge and CM gauge traction motors used. The only datapoint I can find right now in that regard relates to the GE752 and GE761 motors, at about the time the latter was released, when the GE752 was at its 752E iteration.
The GE752, with slowest speed gearing (65 mile/h with 40 inch wheels) had a CTE of 13 250lbf, representing a continuous adhesion of 18.9% against its maximum suitable axle loading of 70 000 lb.
The GE761, with slowest speed gearing (60 mile/h with 36 inch wheels( had a CTE of 8 500 lbf, representing a continuous adhesion of 19.3% against its maximum suitable axle loading of 44 000 lb.
In this context maximum axle loading is not so much a physical limit, but the point beyond which the motor cannot develop additional torque to make use of the incremental adhesion.
Anyway, one could deduce that at the time, eight GE761 motors did not quite equal six of the GE752 type. Thus an 8 x GE761 export derivative of a 6 x GE752 domestic prototype might come up a little short of the latter in terms of delivered performance.
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?
Also, I see from this thread - Promised new "Unbuilt" YouTube series - Trains Magazine - Trains News Wire, Railroad News, Railroad Industry News, Web Cams, and Forms - that eight-motor locomotives for Australian standard gauge application were previously mooted, although in D-D rather than B-B-B-B form.
Cheers,
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.
Before that were:
P&N #5601, home-built, was described in RA 1925 January 17, which implies that it was built during 1924. It had Westinghouse equipment, and weighed 190 000 lb. RA described it as “unique”, which suggests that it might have been the first of the span bolster type.
P&N #5602, also home built, using some existing parts from earlier locomotives, was described in RA 1930 April 19. It had Westinghouse equipment and weighed 200 000 lb.
Photographic evidence on the internet indicates that there was also #5600, apparently home built/rebuilt. Basis its number, it might have preceded #5601, but then the latter would not have been unique. Again from the internet, it was later rebuilt in heavier form (to match #5611?) and renumbered as #5612.
Thus, P&N had at least four span-bolster four-truck locomotives, and it could well have been the first to use this form. More certain is that it was the first to use the articulated span bolster B-B+B-B form.
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,
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.
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 .
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.
Peter
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 h