Don’t forget that the SP ordered an additional 15 KM units (with hood carbodies) about the same time as they ordered the Alco’s.
One attractive factor for the SP with the potentially higher factor of adhesion and higher continuous tractive effort for a given weight of locomotive, is reducing the percentage of overall train weight taken up by the locomotive. I would guess that ca 1960, the locomotives ascending “The Hill” would represent between 15 to 20% of the weight of the train (assuming continuous tractive effort was equivalent to 13-14% coeficient of adhesion and a 2.2% grade).
One of the things mentioned in the June 1976 TRAINS article was that coupled drive axles were a major factor in contributing to improved adhesion. Perhaps the French were on the right track with the “monomoteur” truck in which one larger traction motor drives both axles.
I did not know that the USA banned the Germans from developing the diesel electrics. Well as you say the Germans just developed DH’s, there’s always a way around that. The US Army used diesel electrics in W Germany, but as far as I know as soon as armys left the Germans stopped useing these DE’s.
But labour was cheap because of the war and of good quality, wich helped in the manufacturing of the DH’s I would think. As compared to “Flatwheel Jct” somewhere on the long route of the SP or mountain lines of the Rio Grand. Labour costs today are high for anything at all in Germany.
Lots of interesting info on that site, however I should point out one minor mistake concerning one of the two preserved ‘Warships’. D821 “Greyhound” was in the fact the last working member of the class and was bought by the Diesel Traction Group in January 1973 - the first main line diesel loco to be privately preserved in Britain. (For our purposes I am not including switchers/shunters).
The DTG ( http://www.westernchampion.co.uk/ ) had originally tried to acquire a D6300 class loco and in fact had paid the money to BR to buy D6319 the last survivor. But she was cut up at Swindon by mistake. After an angry phone call to the BR chairman they were offered D821 at the same price.
Subsequently the DTG have acquired the locos listed on their site. Except for “Western Champion” all their locos have run on the North Yorkshire Moors Railway but are no longer based there. D821 is based at the Severn Valley Railway ( www.svr-vlo.org.uk/floodline.htm ), D1015 and D7029 at the EWS depot at Old Oak Common and D8568 at the Chinnor and Princes Risborough railway.
D832 “Onslaught” was used by BR’s research department for several years after its withdrawal until eventually bought and restored by the East Lancs. Railway.
Was wondering how speed control was accomplished? Was the engine speed brought up to a fixed rpm and then the speed controlled by shifting valving in the auto tranny? Or was the speed controlled by linearly controlling engine speed? How was the speed control compatible with the Diesel Electric Notches?
If I remember this correctly there are 3 torque converters optimized for different speeds, and they are actually emptied and filled sequentially to change the speed range.
The ‘r’ in their designation indicates a hydrodynamic ‘retarder’ which takes the form of two fluid couplings.
As one of these transmissions has been rebuilt to operating condition I expect there are detail pictures somewhere here:
That’s what I remember as well. At optimum engine/track speed ratios, the Voith transmissions were about 85% efficient, which was about the same as a contemporary diesel electric with DC traction generator and DC motors.
This is different but can be compared. I drive a hydraulic powered Deere. The performance is great over all speeds with the “prime” mover running at top speed. Can maintain speeds to 1/2 MPH and suspect probably 1/10 MPH. Speed control is very precise although no way to compare to electric drive.
Absolutely no unplanned maintenance on hydraulic drive with over 1000 hours.
BTW the pulling power is much greater than a Craftsman I own of the same HP.
Hydraulic and electric drives both have improved greatly from the D-H that SP bought.
The 9010 has currently restored one engine. The other engine was beyond repair and the second transmission missing. It appears the first transmission was serviceable and not rebuilt. Little information on theory of the voith transmission operation is mentioned. Supposedly, the KMs were able to get more horsepower to the bogies through the use of a double turbocharged, DOHC, 5 valve per cylinder compact power plants and an 85% efficient fluid drive system.
Back to the speed control question. The transmission supposedly had three torque converters and a torque retarder. The three torque converters, were likely controlled by actuators, and switched in or out through speed ranges. This would imply each converter had some type of gearing effect. But I read that each converter was actually designed for specific efficiency at a specific speed range. This would imply that speed was not controlled through converter shift, just efficiency. Perhaps the retarder was modulated throughout the acceleration process to control speed as well as during the braking process. The retarder did have a 5 valve modulator. Wonder if it worked like a vacuum modulator on a car tranny?
The astounding thing to me when I first read about these is that they have no positive engagement at all, either via some kind of progressive TCC or a lockup as on RDCs.
There are efficiency data for Allisons with no clutches, a couple of clutches, and clutches on all speeds. I have not made a rigorous study of the efficiencies but my overwhelming impression of these things in diesel pushers (Cummins C-range motors, about 833cid if I remember correctly, so larger than an 8-92TA as found in ‘half an SPV2000’) and fuel economy with actively-engaging lockup on all speeds is supposed to be considerably improved.
As I’ve noted with regard to duplex steam locomotive conjugation, a TCC or any other locking clutch on a large locomotive would need to include Ferguson-like functionality against various kinds of road shocks (and to save damage to the universals and gearing) but this would not be difficult for Voith engineers…