The process you describe of using a locomotive on the steeper grades only is not confined to any particular class. Perth Sydney trains often have a third or fourth locomotive added at Parkes before they turn south to Cootamundra. I understand these locomotives are generally called “East Coast Bankers”. (bank is a term for a grade, and helper locomotives are called “bankers” or “bank engines”.)
The AT46C locomotives, known as AN class, are often used on this service. These are the only locomotives on the national system with 16-710G3 engines but without sound mufflers. As a result you can tell before the train comes into sight if the AN class is working. I’ve seen examples where on 4PS6, for example an AN is powered up around Gunning for the long 1 in 66 to Cullerin. Since an AN has more than enough fuel to run from Parkes to the Chullora SFT, the fact that is only turned on for the major grades is an indication that the procedure is for fuel saving and not related to fuel capacity. Often an NR is used that way, only being turned on for the steep grade. Unlike the AN, you would have to watch the stack to see if it was working. The PS trains are often used to transfer NR class dead from Parkes to Chullora.
On the other hand, I saw SCT’s 3MB9 yesterday, with SCT 002 and SCT001. It ran through with both GT46C ACe units running on a light train with only 24 platforms. Of course they use in-line fuelling with a single 20 foot tank container connected to the two locomotives. They can run Melbourne Brisbane with no problem, never exceeding 134 tonnes per unit, and only losing 1/3 the capacity of one 3TEU wagon. But where it really counts, Melbourne to Perth, SCT run through with in line fuelling (while PN trains refuel in Port Augusta and again at Cook and maybe Parkeston), all while never exceeding 134 tonnes per unit. SCT can refuel in Adelaide, where trains from Melbourne can be double stacked and those to Melbourne reduced to single stack.
Its about 629 Km Sydney Yard to Parks via Cootamundra . Melbourne Brisbane is further .
Yes we attach extra units Sydney Parks (either way) and they are generally smaller Fuel capacity units . How often do you see a TT LDP 93 west of Parks , they aren’t going too far without in line fueling . It makes no sense to to detach an NR and keep the shorter range units . I’d say if you’ve seen an NR detached at Goobang East its because the consist was all NRs .
ANs are a bit different . They were short changed with the Power Glide AR11 Alternator , like USD 60 series were , and the 16 710 is limited to keep the AR11 alive . So with a bit over 3800 Hp output they are a bit more frugal than the 4400 Hp ACs .
I have written an article to appear in the September issue of Railway Digest magazine on these locomotives. I was fortunate to get active assistance from Progress Rail in preparing the article. The basic dimensions are:
Type GT46CU ACe gen III Wheel Arrangement Co’Co’ Engine EMD 710G3C-T3 Length 23.7 m Cylinders V-16 Width 2.8 m Power 3200 kW Height 3.9 m
The locomotive power, 4300 HP, 3200 kW is the input to the alternator. I understand the brake horsepower is 4500.
I don’t know what the limiting speed of the traction motors is.
As I understand it the only GT46C ACe Gen 2 are the three GWB locomotives.
I understand that the GWBs do not meet NSW EPA sound requirements. I think this might be due to the walkway behind the hood, which allows the sound of the fan motors to spread more widely. The main difference between the Gen 1 and Gen 2 is that the Gen 2 has only a single inverter compartment which contains the two inverters, one for each truck.
All of the GT46C ACe locomotives use Mitsubishi inverters although the Gen 1 locomotives use Siemens design traction motors built by EMD. Only the GT42CU-AC (4000 class) locomotives use Siemens inverters and traction motors. The 4100 series use Mitsubishi equipment and EMD traction motors.
The Gen III locomotives, all narrow gauge so far, have separate inverters for each traction motor.
I don’t have a handy reference to the difference between Tier 2 and Tier 3 710 engines. I think most of the difference is in the control program and the cooling system.
EMD will supply an engine meeting Tier 0, Tier 2 or Tier 3 as required.
These new locomotives have not worked out as expected…
The GT46CU-ACe locomotives have the same traction motors as the GT42CU-ACe units. The continuous tractive effort is the same as the smaller units. This causes problems on long steep grades.
The following was posted on an Australian forum by user “Sulla 1”
Peter
The Bowen Rail Company (BRC) has begun using a number of leased Pacific National 83 class this week - as it deals with unexpected locomotive shortages on its Carmichael Rail Network and Aurizon’s Newlands Line. The leased 83s appear to come from PN’s final group - 8347 to 8352 - purchased from Downer in 2018 (previously owned by Downer as 8347 & LDP016-LDP020).
BRC has been experiencing issues with its GT46CU-ACe Gen III 4600s as they struggle to meet the company’s expectations of hauling 86-wagon 9,100-tonne trains on the Newlands system in pairs, whereas Aurizon and PN use three smaller GT42CU-ACe for the same size trains.
The 138-tonne 4600s produce 43% more horsepower than the Aurizon and PN locos, however their starting tractive effort is only 11% more, and continuous ratings are the same - a possible issue on Aurizon’s Newlands Line where a number of grades against loaded trains, inlcuding the 10km long Briaba Bank, require high throttle settings at prolonged low speeds.
BRC currently rosters 14 4600s and has a fleet of 536 106-tonne coal hoppers.
The situation highlights the absence of higher horsepower lease locomotives available for the Queensland market, an
The axle load restrictions in Australia have been previously mentioned, but I still must say that from a North American perspective 138 tons seems very, very light for a 4300 HP freight locomotive.
Not necessarily. South African Railways is primarily Cape Gauge and had some pretty heavy power in the steam era. Consider EFVM in Brazil, which is a meter-gauge version of DMIR in the tropics. They have North American sized power with eight axles mandated by the restrictions on traction motor size due to the gauge.
I don’t think the axle load is relevant in this case. The problem is the continuous tractive effort of the traction motor concerned. The trains have successfully been hauled by three GT42CU-AC locomotives with the same EMD motors but with only 200kN (20 tonnes) on each axle. The problem is not wheelslip but the available tractive effort. the three GT42CU-AC units have 18 motors altogether but the two GT46CU-ACe units have only twelve of the same motors.
Before the line between Collinsville and Briaba was realigned and regraded, I recall driving beside a train with two GT42CU-AC units. The lead axle was clearly rotating slightly faster than the others on the two units. Clearly it couldn’t run much faster since the speed was governed by the inverter frequency. I have no idea how much tractive effort would be lost with this occurring.
No I don’t think you’re right there M , I believe axle load is very important in the adhesion stakes .
Yes the traction motors have to generate adequate torque but if thats enough to overpower the wheels contact patch then you can’t put the full power to the rail .
It’s sounding like these narrow gauge engines were short changed traction motor wise . What the US builders tended to do was fit larger diameter wheels so that larger diameter traction motors didn’t drag in the ballast …
If you had a 90MAC to look at you’d notice it . Obviously the reason these had HTCR2 trucks was to increase the wheelbase for larger diameter wheels and motors .
The major problem we have in Australia (outside the Pilbara where everything is built to heavy haul US Standards) is that the rail infrastructure systems are buillt light by American standards .
Ask them what they’d think of running 47/53/60 Kg to the meter rails . They are running I think mostly 68Kg/meter rails on heavier concrete sleepers and sub base . This is why a heavy coal hopper in the NSW Hunter Valley weighs 120 metric tonnes where a heavy ore car in the Pilbara weighs 168 metric tonnes .
That coal setup in QLD had the opportunity to build it’s own standard gauge railway , but they cheaped out by wanting to connect to the existing QLD narrow gauge light load rail infrastructure .
You would think that had they gone with standard guage it would be built to US domestic standards - like the Pilbara railways . No brainer , could have had modern 190 odd metric tonne USD locomotives hauling considerably larger loads .
I’d be very interested to hear how much a GT46ACe Gen 111 cost compared to a Tier 3 SD70ACe or ES44AC .
It’s a great pity . The powers that be in eastern Australia really needed to see how well US spec perway and locos + rollingstock work . Cheaper and far more productive in the long run .
Minor correction - the wheelbase on the HTCR and HTCR-II trucks is the same overall at 164 inches, the spacing between axles on the HTCR is 1-2 80" and 2-3 84"; on the HTCR-II it’s equal at each 82". The larger 45" wheels on the HTCR-II force the bottom plate to be higher at 51" compared to 49.38" for the HTCR with 42" wheels.
Point taken , what I had to compare is HTCR2 vs HTSC2 .
SD90MAC vs SD70ACe . I believe the MAC has larger traction motors than the ACe though I’d have to look at specs to see if a 70ACe pulls much if any more than a 9043 MAC .
The 70MAC has 1TB2630 motors and the 90MAC 1TB2830. The 26 and 28 numbers are representative of diameter but not exactly in inches, both are Siemens designs. The 70ACe uses an EMD design to go with the Mitsubishi inverters that is between those two in diameter and designated the A3432. EMD also currently uses the A29XX motors of varying core length in many or most export locos which is the same diameter as the 1TB2630.
The standard gauge GT46C ACe units built in Australia had the 1TB2630, and I think the units being built in the USA now also have this motor. The extra 14.5 inches (or more, since the motors are built to fit one metre gauge) of armature length compared to the narrow gauge motor mean that the standard gauge locomotives aren’t limited by the continuous tractive effort like the narrow gauge units. I have a Siemens brochure somewhere that illustrates the 1TB2630 and 1TB2830 motors. The 1TB2830 had double helical pinion and gears in the illustration, suggesting that Siemens were taking the extra torque very seriously.
I think I was told that the A3432 was too big in diameter to fit the export truck designs even on standard gauge, and that there was a Mitsubishi design that was considered before the 1TB2630 was selected.
Not quite. A herringbone gear acts like two skew-angled spur gears together – the Citroen company emblem was derived from that piece of history.
While they eliminate end-thrust they still have some progressive tooth-engagement issues, which are addressed with helical teeth. Pairing opposite-handed helical gears in herringbone fashion gives you the double-helical form…