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Paul Milenkovic which of course had mechanically connected driving wheels and why the railroads having dealt with connected drives on steam would suddenly throw up their hands maintaining the wheels on the Diesel hydraulic.
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Overmod Would be highly interesting to see the pinout on that cable!
Would be highly interesting to see the pinout on that cable!
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Pneudyne That’s most interesting. Is there any more detailed information available on the interfaces between the KC99 master controller and the engine speed control on the one hand and the hydrodynamic brake effort on the other?
That’s most interesting. Is there any more detailed information available on the interfaces between the KC99 master controller and the engine speed control on the one hand and the hydrodynamic brake effort on the other?
Howard Wise is the go to person for MU, controller, and transmission valving info. He is the restoration foreman for the SP 9010 and can be emailed. I have not been privy to any electrical, pneumatic or hydraulic schematics.
In the engine speed control case, one may see that a unit that converted the standard A, B, C and D trainline signals into varying air pressure for the Maybach governor would have provided for eight notches, perhaps those with even numbers. But it would appear that at least one additional trainline signal (in conjunction with the standard four) would be required to obtain the intermediate notches. If so, then presumably the KC99 was adapted to provide this.
As far as I know, the brake effort control on the Voith hydrodynamic brake unit was done by a gate valve operated either pneumatically, with continuous variation, or electropneumatically. In the latter case there were three-piston eight-step and four-piston sixteen-step operators available. So the interface unit would need to have converted from the standard dynamic brake control variable voltage (0 to 74 volts) on a single trainwire to a form suitable for whichever type of operator was used. That looks to have been a more difficult task than for the engine speed control case.
Regarding throttle control notch count, apparently the early German experience showed that the six notches used on the DB V200 were insufficient, and went to 15 on later derivatives. British Rail found the same with the six or seven notches on its early diesel-hydraulics, and went to continuously variable pneumatic control on its later models.
With torque converter transmissions, engine loading follows the propellor law, essentially a cubic curve with respect to rotational speed. Or to put it another way, the engine speed vs. engine load curve is a cube root curve. Thus for approximately equal load increments, engine speed increments tend to be quite large in the lower notches, closing up noticeably at the higher notches. With diesel-electrics, depending upon the load control system used, there is some elasticity in the load vs. engine speed relationship, so that equal engine speed increments through the notches is commonplace, although not universal.
Outside of Germany, the standard mid-1960s diesel-hydraulic export models from Henschel and Krupp seemed to have worked quite well. In particular there were large fleets of these in Burma, Thailand and Indonesia that had long lives and operated alongside diesel-electric locomotives. They were relatively light B-B units in the 1200 to 1500 hp range, certainly lighter and with lower axle loadings than the available diesel-electrics of the time. All of these had Voith transmissions, some with hydrodynamic brakes. And JNR, Japan had a large fleet (over 600) of its long-lived DD51 class, with the unusual B-2-B wheel arrangement. These had Voith-type transmissions. As far as I know, the very first had seven-notch throttle controls, but a change was made to 14-notches for mass production. If so, that would seem to have echoed the German experience.
Cheers,
Overmod A vastly, dramatically amplified version of what they warned you would happen if you engaged Drive on your automatic transmission while rolling backward. High overpressure on the turbine, at the very least. Of course it would be interlocked to prevent this, as described graphically in the '70s article in Trains: there's a reversing gearbox for each truck, it is locked until the engine has been at idle long enough for line pressure to drop or the low-speed turbine to empty, then it unlocks and a servo winds it to opposite engagement, where it locks again before you can get the throttle out of idle or start filling the converter... Memorable that it took 30 seconds or more for the whole process -- clunk, clunk, clunk, clunk. The thought of switching with one makes me wonder if that was one purpose of the F unit Espee ran with the single K-Ms in later years...
A vastly, dramatically amplified version of what they warned you would happen if you engaged Drive on your automatic transmission while rolling backward. High overpressure on the turbine, at the very least.
Of course it would be interlocked to prevent this, as described graphically in the '70s article in Trains: there's a reversing gearbox for each truck, it is locked until the engine has been at idle long enough for line pressure to drop or the low-speed turbine to empty, then it unlocks and a servo winds it to opposite engagement, where it locks again before you can get the throttle out of idle or start filling the converter...
Memorable that it took 30 seconds or more for the whole process -- clunk, clunk, clunk, clunk. The thought of switching with one makes me wonder if that was one purpose of the F unit Espee ran with the single K-Ms in later years...
Guess I will have to buy Nov 62 issue of Trains magazine to see the KM transmission write up. I had heard the Maybach engine was originally outfitted with a pneumatic governor and quickly modified by SP to a different governor for increased MU compatibility. Pictures of the Maybach engine at Niles Canyon do not appear to have a Woodward governor. There is however a 13 pin connector mounted to the engine perhaps for governor management or sensors. It would be interesting to see how the MU control lines interfaced with both the 31 pin connector on the transmission and the 13 pin engine connector. I also read that the advantage of the Voith transmission as opposed to the Maybach transmission, was that the Maybach transmission shifted like a car with gear to next gear shift shudder. As far as being able to accidentally shift into reverse while still moving in a forward direction, there likely was a reverse valve configuration which may have taken time to setup, I do not know if it is 30 seconds...This link may speak to it https://www.facebook.com/186409164738195/photos/a.186444211401357/405866956125747. Did read there was an extra air valve on the engine, separate from the governor, whose function was to raise engine rpm to notch six during hydraulic braking to remove the excess heat..
There was also a compressed air input to the transmission/retarder. My understanding is the compressed air was applied to the transmission fluid reservoir tanks by pneumatic solenoids. The compressed air would push the fluid into the converter when needed and when released, the fluid would drain from the converter back to the reservoir.
The following are quotes from the 9010 restoration crew: The brake system is set up by the "selector lever" located on the control stand. The Maybach speed is controlled by an air operated governor that is itself controlled by electrically operated valves that receive their signals from the control stand. The 27 pin MU signals include the control signals for the hydrodynamic brake.
The brake is controlled by the throttle, just like on a DE but through a custom built interface. MU control of the brake is via an interface between the "point potential" signal in the MU and the brake valves.By the way, engine speed increase in dynamic is controlled by activating the "C" valve in the governor of a DE. That same signal is sent via the MU to the Maybach governor controller. On a DE, the speed increase is to increase the traction motor and engine cooling fan speeds. In point of fact, there is a large rheostat in the bottom of the control stand that provides the pin 24 signal when the KM is leading. In addition, the analog signal is also converted to a stepped signal for the field loop circuit so the KM's could operate in MU with locomotives of either point potential or field loop type control. By the way, only steps 1 and 2 of the throttle don't do anything. Step 3 causes transmission converter filling so is a power step equivalent to run 1. Step 2 was intended to be a partial converter fill for creeping but was never installed.
Remain stopped for at least 30 seconds to change from forward to reverse eh.... ...that alone would make everyone hate them.
Worse for switching than anything GE ever made!
Greetings from Alberta
-an Articulate Malcontent
SD70DudeSo, just out of curiosity, what would happen inside the transmission if an engineer reduced the throttle to idle, moved the reverser to the opposite direction, and throttled up again before the locomotive had come to a complete stop?
So, just out of curiosity, what would happen inside the transmission if an engineer reduced the throttle to idle, moved the reverser to the opposite direction, and throttled up again before the locomotive had come to a complete stop?
Not that anyone used to diesel-electrics would ever do that while switching........
The first place I saw the Voith transmission referenced was in the Encyclopedia of World Railway Locomotives, where the sequential filling and emptying of the converters is described. I don't think I've seen a reference that indicates the 'shifting' is controlled by something other than road speed, but I suspect there are other controls involved secondarily (e.g. engine governor control during the period the 'shift' is executing).
Did find this in regards to transmission
The Voith transmission was totally different. In the Voith, either three, or sometimes only two, torque convertors are installed inside the transmission. Only one of them is actually in use at any one time, and the transmission governor uses only the input of locomotive axle speed to select which one is in use. The transmission actually fills the convertor to be used with transmission fluid, keeping the unused convertor(s) empty of fluid. When the required speed to change convertors is reached, the oncoming convertor is filled with fluid; when it is filled, the one in use prior is emptied. This effectively alters the driving ratio as the various torque convertors are of different sizes, and can reduce shaft speed (which also includes torque increase) in various amounts. With the three-convertor transmission, as an example, the first convertor to be used from starting is the largest, offers the most torque increase, the largest speed reduction, and can dissipate the most heat. The convertors are smaller as speed increases. The two convertor transmission was not generally as popular as the three convertor type, but was used on units built for Austria and for East Germany, among others.
Additionally, there is a 31 conductor cable attached to the transmission connector, per Niles Canyon restoration crew. Likely control circuitry for braking and reverse.
tree68 I read somewhere that there was some concern (among crews?) about that big shaft spinning under one's feet as you sat in the cab.
I read somewhere that there was some concern (among crews?) about that big shaft spinning under one's feet as you sat in the cab.
I did read that these locomotives were paired with "F's" in case of drive shaft "pops"....would assume a "scatter shield" wasn't needed or installed. The driveshafts in the Alco-holics appear very robust...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
About maintenance,
Found this quote on maintenance of this locomotive
"talked to a former SP trainman, he mentioned the bleeding obvious as to why the Alcohaulics outlasted the K-M units but left so soon: maintenance. The DH643 had numerous parts that were interchangeable with other Alco road units (esp. RS11's, C628s). Whereas the KM's were orphan-engined and required metric tooling. The transmission was the primary reason for retirement, lack of parts."
How often did SP have to change the transmission fluid or rebuild them? How did this compare to the cost of replacing brushes etc and rebuilding traction motors?
SP seems to have eventually standardized on the 3000 to 3600 HP diesel-electric units that entered production in the mid to late 1960s.
Former Car Maintainer It would seem to me that modern day, diesel electrics with electronic inverters would certainly negate the possible benefits of a hydraulic drive. Except, electronic inverter technology was not available when the diesel-hydraulic was shelved.
It would seem to me that modern day, diesel electrics with electronic inverters would certainly negate the possible benefits of a hydraulic drive. Except, electronic inverter technology was not available when the diesel-hydraulic was shelved.
Correct on both points.
The traction alternator/rectifier/inverter/AC motor arrangement has the advantages of both being mechanically simpler and more efficient than the diesel hydraulic drive. Combine this with nearly instantaneous response to traction control signals, the achievabke coefficient of adhesion is also better than the hydraulics.
The key breakthrough in inverter technology was the development of IGBT's that were large enough for use in a locomotive. The inverter per axle eliminated the requirement for tight control on wheel diameter that was needed for the diesel hydraulics and the inverter per axle implementations with GTO Thyristors.
I looked at the work now being performed to restore one of these locomotives at the Niles Canyon Museum. Multiple drive shafts/universal joints/gear boxes and hydraulic transmission. Quite a contraption. I guess it depended on what broke and how often, and whether the failures were induced by operational demands beyond its design. At first glance it wouldn't appear to be more difficult to maintain than a diesel electric. Certainly traction motor repair was eliminated. Perhaps it was the three axle bogies and the wheel cutting restrictions. I wonder if the design of the Alco-draulics were copies of ML 4000s. Very little info out there.
The Kruas Maeffi ML4000's were very complicated and needed a lot of maintence. They spent a lot of time in the shops because they were so complicated. This information came from a roundhouse foreman that I knew. His crew worked on them.
It would seem to me that modern day, diesel electrics with electronic inverters would certainly negate the possible benefits of a hydraulic drive. Except, electronic inverter technology was not available when the diesel-hydraulic was shelved. Must have been the maintenance complexity of the plumbing ,complex gear box/drive shaft assemblies on the bogies, wheel cutting limitations, and awkward MU compatibility. In theory, the hydraulic drive should have provided better adhesion, nil wheel slip, a true throttled vs stepped speed control, and elimination of traction motor repair. Wonder if the Niles Canyon has practical information on them?
QUOTE: Originally posted by marcimmeker I think they lasted 20 years in Spain. There were also various subtypes for the TALGO trains. They ran even longer. greetings, Marc Immeker
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