I live in Germany, where most of the diesel locomotives are diesel hydraulic/DH. For some reason, the DB (West German Federal Railway) and the DR (East German “Reichs” Railway) were against procuring diesel-electrics/DEs, although many European locomotive manufacturers produce(d) DEs for export to other parts of the world. I know that Krauss Maffei sold/lent several DH prototypes to Union Pacific, but for some reason, they never caught on in the US. Now does anybody know the particular advantages or disadvantages of DH versus DE?
The KM DH’s went to Southern Pacific.
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Disadvantage was they did not MU with American locomotives.
differend air and electtrical control systems.
I heard that they were just too difficult to maintain. The hyraulic transmissions worked fine, but the locos requied German, not US, maintenance.
The same basic thing happened in WWII, not to bring up a sore subject, but the Americans built the Jeep. A vehicle that could be maintained with a screwdriver, wrench and hammer. It could be easily built in mass production.
The equivalent German vehicle was difficult to maintain and impossible to mass produce. It may have been a better engineered vehicle, but it wasn’t designed for the right purpose. That purpose being: Easy to use and build with reliability and with minimal, simple maintenance.
“You Gotta Know the Territory”. Krauss Maffei aparently didn’t.
They also required significantly higher maintenance, much of which was for truing the wheels to a much closer tolerance on and between common powered axles to accommodate the hydraulic transmissions powering more than 1 axle per truck (when you have one traction motor per axle you don’t have to worry about whether wheels on the next axle are the same diameter). Uneven wear was a major factor that apparently killed their performance on American track.
So Greyhounds hit the nail right on the head.
This problem is not unusual for European equipment operated over here (no insult intended–just a fact of life). Because of historic proactive and benevolent European policies regarding rail and rail labor, they operate to different standards that incorporate tighter tolerances and therefore have to perform more maintenance (generally with better trained personnel than we have), but their governments historically provided the necessary funds. Their equipment is generally lighter due to buffing requirements about half ours, which results in entirely different dynamics and wear, as well. This situation creeates an entirely different operations/maintenance scenario than is dealt with on the US railroads.
But it comes down to issues like what my late, great old friend Charlie Luna (UTU founder and incorporator of Amtrak and long-time board member) once commented to me regarding the European Wagon Union trucks under the Superliner I equipment: How do they think some car knocker with a 3’ crescent wrench and a sledge hammer is going keep the shims in that truck?
Werkspoor said it all. (DRGW had one K-M and got rid of it quickly - to SP)…also the oddball/orphan factor has to be considered as well. (What hurt F-M, Erie, BLW and Alco as well)…
In Britain the Western Region of Briitsh Rail decided to order diesel hydraulic locos. The justification for this was that the 2000hp West German V200 class weighed just 80 tons whereas the English Electric Co’s 2000hp diesel electric (BR Class 40) weghed over 130 tons. Had the WR been allowed to buy diesel hydraulic locos direct from German manufacturers they might have been more reliable but they had to buy the locos from British firms who were subcontract to the German firms. These British firms did a shoddy job with the result that the WR’s diesel hydraulics were dogged with problems. When these were sorted out the D800 “Warship” class (BR Class 42- closely based on the German V200 class) eventually achieved higher mileages than the diesel electric class 40’s. But the “Warships” were much more costly to run. By the mid 1960’s the WR had been forbidden to buy any more diesel hydraulics; instead it had to order the diesel electric locos which had now been chosen as national standards (in the 1950’s all the regions of BR were allowed to choose what diesel locos to bu which resulted in too many different classes being ordered; some of the early diesel electric classes were also very unreliable).
In 1968 BR decided to phase out all diesel classes that were either unreliable or small in number. The WR diesel hydraulics certainly fell into the second category so they were all scrapped by 1977.
OK. The original order for 6 KM’s were for 3 to the DRGW and 3 to the SP. The DRGW decided that the DH’s were not a good fit, but the SP still was working with them, so the SP took the 3 DRGW units. The SP then ordered a set of (I think it was) 12 units from K-M and 3 from ALCO. The first six were “covered wagons” and the balance were “hoods”.
Several of the problems with these locomotives have been mentioned above. Chief among them were the engineering standards (much different), familuarity with the technology ( a problem shared with the diesel-electric when EMD first introduced them) and maintainence standards.
One “problem” not mentioned was that both the DRGW and the SP bought them for the wrong reasons and for the wrong service. The DH is a constant torque design, and as such, with sufficient horsepower to move a heavy train at speed, can’t get the train started because of too much torque to the rail at very slow speeds. The diesel-electric, however, is a variable torque design and can start anything provided the wheels don’t slip. It requires, however, a lot of horses to move that train at speed where the DH does not. This also speaks directly to wheel-slip control which is easy on an electric transmission and never really accomplished on (at least) the US hydrolics and also to the wheel wear problem.
The SP and the DRGW first used these engines in the Rockies (Tennessee Pass) and over Donner - not good places for DH drives.
At the very end of their use on SP, they were finally placed in their best service application – TOFC trains. One K-M and and F-7 could move an “I-5 Corridor Trailer Train” (LABRT; OABRT; BROAT; BRLAT) on a passenger schedule that included stops at Roseville and Eugene for yard work. It later took 4 to 6 SD-40/45 units to do the same thing. The F-7 got the train started, and once the “***” could keep its feet, look out down the track.
The hydrolic would have thrived on the SP if they had been put into the pro
Oh, yes they did. From square one. But the “***” generally had to operate as the lead unit.
Lee — take a close look at the service assignments for the various types of power. Hydrolics normal assignments are light duty freight and passenger where there is no overhead wires, yard switching and industry switching.
Electrics do the heavy stuff - for two basic reasons - that they can haul a heavier train at speed then your European DH and when the HP/Torque curve starts to head down on an electric, it can “suck” more “juice” from the overhead and effectively increase its HP - thus going faster than either a DE or a DH.
Mind you, all the new DMU’s in Briain (except for the Virgin Voyagers) have hydraulic transmission.
That’s the main advantage the DH has over the DE - it weighs a lot less. Given the maximum axle loads on German rails at the time (about 20 tons on main lines, 15 on secondaries) it was simply possible to have more power on less axles in the same engine.
Nowadays the DE is the technology of choice in Germany as well - if it comes to big new Diesels they’ll be Diesel-electrics due to improved control electronics. These allow for better traction control and make the locos more versatile than their DH counterparts. Also, weight is no longer that limiting a factor, given that German mainlines have been upgraded now to 22 tons permissible axle load in general.
Regards
Andreas
I believe that there is some usage of small diesel hydraulic locomotives in North America, mainly for underground mining. I would guess that this is due to their ability to operate in wet track conditions, but also for fire/explosion supression (i.e in a situation where methane gas levels make electrical equipment less favorable). I know Brookville equipment builds some hydraulic transmission locomotives.
I think SP got 18, and Rio Grande got 3.
The SP and DRGW each got 3 in 1961. TJese had a full width carbody. In 1963, the SP went back for 15 more with a road switcher carbody. The DGRW sold their 3 to the SP in 1964
The book I have, ‘Diesel Locomotives: The First 50 Years’, by Louis A. Marre says they" came with all-pneumatic control, which was changed to electropneumatic by the railroads so the KMs could operate in multiple with conventional diesel-electrics."
One might point out that a very successful application of diesel hydraulic transmission was – and is, in a few locations – the Budd RDC cars. It is interesting to compare them, though, with some of the comments above: the transmissions powered only one of the two axles on each truck – thus the wheel wear problem was not a factor. They didn’t have to MU with anything else with different control strategies. They were not intended to pull other cars, but to accelerate and run quickly on their own (not to say the couldn’t: they did, and could, but they weren’t supposed to…). They used readily available, pretty darn close to stock GM engines and transmissions.
Interesting, eh?
The New Haven had a special high-speed trainset called the Dan’l Webster that was diesel/hydraulic. Was built in 1956 by Baldwin Lima Hamilton.
It was a total flop and got scrapped.
AFAIK, the Dan’l Webster’s engines were DH with Maybach engines from Germany. Transmission came from Germany too. The rode very hard, but very very fuel-efficient, at least for the fifties.
The German V200 was developed for light and fast passenger trains. The tried it on freight on hilly lines, but maintenance costs skyrocketed.
Trains did an article on the testing of the Krauss-Maffei’s over the Semmering Pass in the Alps, the issue was in either 1964 or 1965…The units tested were not lettered for Southern Pacific but were tested in their Grey/Red paint schemes. They utilized transitional coupers and pulled European equipment during the tests. I was told that their main downfall was the “oprhan effect” and that they were maintance intensive, and did not hold up well in the “dirtier environment” on the SP.