Hello everybody,
as we all know the Krauss-Maffei diesel hydraulic locomotives were not very successful for a number of different reasons. On the other had in Germany they are still in service. The reason for posting this note is that Herschel produced a two engined European version of the Krauss-Maffei's that were a flop over here. This particular locomotive is still in service and going strong for a rail construction company.
This goes to show how much harsher the demands are on north american equipment.
Frank
PS: If you are interested in viewing the locomotive in question please click on http://de.wikipedia.org/wiki/DB-Baureihe_V_320 . Google can translate it to english.
"If you need a helping hand, you'll find one at the end of your arm."
My understanding is that the Germans have favored diesel hydraulics due to the higher power- to -weight ratio on such locomotives, a plus given the smaller loading gauges on their rail network. This justified the generally higher maintenance costs of diesel hydraulics. Also note that diesel hydraulics historically produced higher tractive effort than an equivalent sized diesel electric but that has changed with the advent of AC traction motors.
I think the most impressive application of D-H technology in US practice were the three 4300 HP DL-643 units that were built by Alco for SP using Voith hydraulic drives..O.C these were just as unsuccessful in operation as the K-M units..
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
There is some suggestion of a hint that the failure of the German DH locomotives or failure of the Voith transmissions had to do with American railroads not wanting to spend on dime on maintenance and on abusing locomotives in road service.
Maintenance is more than simply "this unit is high maintenance" and "this other unit is low maintenance." One of the things attributed to GE in overcoming their reputation for junk locomotives is sending their factory reps out "into the field" to train railroad mechanics "in the way of GE." The GE is not an EMD locomotive, and the people who work on GE's have to know what needs to be done to keep GE's running, that requires training, and GE made an effort to get people that training to improve the reputation and demand for their product. So perhaps the K-M's were kind of thrown into American service without the right level of support for the folks who were supposed to keep them going.
The other thing about the K-M's is it seems that their high horsepower capability was put to work on mountain railroads (portions of SP, much of D&RGW) where these things were run flat out for long periods of time. Perhaps K-M didn't have an appreciation for that level of heavy-duty service. Perhaps DH locomotives in Germany are used in flat lands, and that the heavy-duty lugging in Europe is largely covered by straight electric locomotives.
But it is not clear to me that the hydraulic transmissions were the downfall of these locomotives. Both SP and D&RGW had long tunnels or snow sheds (they have long mountain tunnels in Europe, of course, but we are talking electrified territory), and especially D&RGW had problems with overheating that they attempted to treat with "tunnel motor" type mods of moving the air intakes lower to the ground. Perhaps if these locos were designed with heavier duty cooling systems for both engine and transmission that they would have been OK.
One other thing about the high tractive effort of the DH's and their maintenance quirks. I read somewhere, can't remember if it was a trade magazine such as Railway Age, that one knock on the DH's is that the wheel shop had to keep all of the wheels on a truck the same diameter to within mm accuracy -- it seems that with DE's, the wheels could vary as much as an inch in diameter.
One feature of the rod-drive steam locomotive is that the driving wheels are forced to turn at the same rate, and I imagine that steam locomotive wheel shops had to keep drivers pretty close to the same diameter as with the DH locos, where the wheels were mechanically coupled to turn at the same rate through gears instead of rods. The advantage of mechanically coupled wheels is that you get the average adhesion of the truck instead of the adhesion of the "weakest sister" when the wheels turn independently powered by their own traction motors. A DE locomotive may have more "weight on drivers", but steam locomotives, under some circumstances, may have been able to produce a larger fraction of weight on drivers as tractive effort, and the CC trucked DH locomotive may have functioned as a 2-6-6-2 Mallet in this regard.
Supposedly the EMD/Siemens AC traction motor setup has each C-truck (3-axle truck) on the same AC frequency, meaning that these locomotives at least electronically have coupled drivers acting much as a DH or a steam Mallet locomotive. Do the wheels on AC traction EMD's have to be matched in diameter -- I keep meaning to ask the EMD guy who comes to campus to recruit engineers, and I forget.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Paul MilenkovicDo the wheels on AC traction EMD's have to be matched in diameter --
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Beyond adding fuel, sand, changing brake shoes and keeping the toilet clean anything else required over the 92 day maintenance requirements is considered excessive maintenance on US carrier locomotives. US carriers want their locomotives running full time for the allowed 92 day period.
Never too old to have a happy childhood!
A couple of observations: NYC leased two of Rio Grande's KM's for a period and ran them on the Boston & Albany. They found that the improved adhesion was more a function of coupled axles than of the type of drive (electric or torque converter).
European roads were willing to allow more down time for maintenance than American roads. 90+% availability is not expected. This has the effect of tying up a lot of capital in motive power that isn't on the road generating revenue.
Here is a link to a YouTube Video of K-M's operating in Europe and USA
http://www.youtube.com/watch?v=v6yBaCL-Ux0&feature=related
Here is a link to a Brazilian Railroad Company(E.F.V.M.) that rostered some K-M ML-4000 Hood units as well:
http://www.tsfr.org/~efbrazil/efvm.html
Well now I can bring up something that's been bothering me since I read it. An article explaining the basics of a hydraulic powered locomotive stated that the engine operated a hydraulic drive. But then it said that this drive simply operated a generator as in a regular locomotive and that provided an electric current...well you know the rest. This all made no sense to me and other things I have read state the hydraulic drive is directly connected to the driving wheels. So..can anyone clarify please?
What is commonly referred to as a hydraulic drive is actually a torque converter drive, not that different from the automatic transmission on your car. The diesel engine crankshaft is connected to the torque converter, which is in turn directly linked by drive shafts to the wheels.
First, the hydraulic transmission/torque converter was much simpler and supposedly less costly than an electric drive.
Second, the hydraulic drive eliminated traction motor flash-over from snow infiltration.
Third, the live axle load was reduced.
I suspect, as has been alluded by others, that customer service and maintenance training left a little to be desired. The Rio Grande did make subsequent orders. It seems that it was the larger SP didn't want to deal with these different locomotives.
HarveyK400First, the hydraulic transmission/torque converter was much simpler and supposedly less costly than an electric drive.
Now days Hydraulic pumps and motors are much more reliable than when these units were delivered to the DRG&W. Almost all very heavy and light weight construction equippment uses Hydraulic motors. A big difference is the operating enviroment of construction equipment being mostly intermittent use and the locomotives need ability to operate non stop at full power for up to 4-6 hrs.
HarveyK400 I suspect, as has been alluded by others, that customer service and maintenance training left a little to be desired. The Rio Grande did make subsequent orders. It seems that it was the larger SP didn't want to deal with these different locomotives.
You've got it turned around. Rio Grande sold its KM's to SP in 1964. SP ordered 15 additional locomotives from KM (the hood units) at that time and also ordered three C-643H's from Alco.
For a number of European locomotive types with AC traction motors (fed by a common converter) the maximum difference in wheel diameter is set at about 1/4 inch (6 mm) on wheels with 50 inch (1250 mm) diameter. I' ve seen values of wheel diameter difference of typically about 1/10 inch and some as high as 3/10 inch. For 40 inch wheels the difference would be somewhat lower, let's say 2/10 inch.
The KM hydraulics had lighter (and faster running) diesel engines and a sophisticated engine contol. These were parts not well accepted by the American customers.The diesel engines surely suffered from high altitude operation and the SP tunnel conditions (there were no experiences in Germany regarding MU operation in long tunnels).
The hydraulic gear boxes did well in many oversea countries, even in Central Africa (where after a few years the locos lack anything not essential for running). Compared to AC traction the hydraulics do not need as low cooling air temperatures as needed for AC converter cooling.With a hydraulic you can run on tracks flooded by water as there is no risk of a traction motor flash over. So much for harsh operating conditions.
Voith in Germany has recently built new hydraulic locos, 4- and 6-axle. The 6-axle with a 5000 hp engine and a split transmission (one for each C-truck). Some 4-axle locos were built for German Railways. The 6-axle probably is for the export market.
Paul MilenkovicDo the wheels on AC traction EMD's have to be matched in diameter -- I keep meaning to ask the EMD guy who comes to campus to recruit engineers, and I forget
2/16 within truck, 8/16 truck to truck on EMD AC motors
Our community is FREE to join. To participate you must either login or register for an account.