diminished horespower in rebuilds

[Overmod]

Weirdly enough, I would NOT have expected most of the crank breaks to be at the flywheel end. I'd have thought somewhere in between pairs of cylinders inducing the greatest mutual torsion... not working against flywheel inertia. I learn something every day from Randy...

Where were most of the breaks on the 16-cylinder 244s? (I've always wanted to know that!)

This isn't directly germane to *locomotive* crank breaks, but IIRC the breakage of GM truck diesel cranks is often somewhere other than at the rear main bearing. I read an account of one person with a 6.5TD who had a broken crank between the first and second pairs of cylinders. His complaint was that the engine ran a bit rough, and only seemed to make about 75% power... he was so right! Only the rear six cylinders were actually providing effective torque; the two in the front were mainly driving the auxiliaries; there was just enough interference between the two broken halves that they stayed in rough sync (think about how the injection pump wandered in and out of 'time' though, depending upon effective torsion... !)

[Randy Stahl]

I've seen a similar situation on an EMD. A broken crank at the accessory end caused by faulty air compressor grommets, the air compressor siezed up and snapped the crank between #1 and #2 mains. The locomotive ran... sort of, with only the rear 14 cylinders. Not much for oil pressure though. I recall the bosses running the engine up until it siezed.
Randy

[Anonymous]

I know on Detroits, the air box covers have pockets cast into them. Because Detroits recieve their air from the V, broken rings, metal shavings, whatever is loose in the cylinder flies right into those pockets. Is this the case with EMD's?

What Randy says about where cranks break makes sense, when a crank "winds up", the greatest stress should be at the flywheel end. Usually what causes a crank to fail is fatigue from tortional vibration. Tiny cracks form in the filets around the oil holes and the filets between the journals and crank lobes. If two cracks meet, the failure begines a greatly accelerated pace.

If the crank fails elswhere it is probably due to some extreme shock like a siezed piston, hydraulic lock, or an imperfection - an Inclusion - in the metal. These types of failure are immediately recognizable by the crystaline structure of the fracture.

A failure by fatigue over a long period of time will show a very small definate starting point with circles of increasing radius growing from that point - "beach marks", the fracture as a whole will have a smooth appearence, usually the last part of a fatigue fracture will be crystaline as the remaining material is no longer strong enough for a typical load.

Oh, I just have to add, RANDY IS THE MAN!!!!! - most of what we say is speculation, leave it to Randy to say say something that puts it all to rest !![8D]

[Anonymous]

I find no possible justfication for nueturing engines. I would want the engine to be big and strong because the more horses availible to do the work... the less "work" the engine has to do to move the load. Makes sense?

I have driven a Cummins M11 under steel loads (slightly more than 320 horses) and burned basically all the fuel per hour I could get into the engine while crossing mountains. A more expensive Detroit or Caterpiller at a higher horsepower rating will get the same load up the hill without burning so much fuel or stressing the componets.

For railroads, I am thinking why isnt the load on the engines constant, they are basically turning a generator to create electricity for the motors down below? If you only can create so much Wattage and Amps to a certain limit to feed your motors.

To me stripping engines in a shop takes man hours that costs money. I think any kind of savings will be wiped out by this work and also any future problems that will come up down the road.

[2c]

[GMS-AU]

Down-rating engines happens in the truck industry as well for the same reasons. The Cummins M11 engine can come in various ratings down to about 240 hp. At this hp the engine will " live " longer as it is under stress. Remember the old Cummins 300 was about a 13 litre's engine where as the M11 at 11 litres is of course 320 hp. More hp for less capacity, and I guess a shorter engine life. Look at the car industry and the sort of power that is available out of say a 2 litre 4 cylinder engine these days with EFI.

True on a diesel loco load on the engine may be the same but if the engine is derated then it simply can't supply as much power to the alternator and that will help the traction motors last a little longer as well. I am presuming the engine is stripped as it needs it anyway so when it is rebuilt then it is downrated then. As discussed here and elsewhere the 2 stroke is at its peak economy per fuel consumed at about notch 7, up in the rev range where the turbo is free wheeling. ( Please correct me if I am wrong here )

On WC's SD45's were they downrated to 3200 hp to prolong engine life and increase economy? ( If at all ) I would presume that would only be done via the injector pump and not a total rebuild.

G M Simpson

[M636C]

With all this discussion of "blanking cylinders" I feel I should mention the main propulsion engines of the Royal Australian Navy's "Anzac" class Frigates, which are an MTU 12-1163 TB93, a German built four stroke with a similar bore and stroke to the EMD 710, 230mm x 280mm. They have an extremely complex system of turbocharging, made more complex by the fact that the engine can be run using one bank of six cylinders only, so the ducting has valves to ensure that the exhaust and inlet passages only supply (and receive from) the six working cylinders. I believe the inlet and exhaust valves on the shut down bank are held open to reduce pumping losses, but I can't remember how. I was shown one of these engines at the factory, and the turbochargers and ducting pretty much doubled the height of the engine.

The reason for wanting one quarter or less power is that the resistance of a ship through the water varies as the CUBE of the speed, so to go twice as fast requires EIGHT times the power. When you are just cruising around waiting for something, the additional fuel saving is worthwhile.

This engine has a maximum power of 6000 HP compared with the similar sized EMD 710 which would be rated about 3000 HP under the same conditions. The ship can make about 23 knots with both MTU diesels at full power, but can run at more than 27 knots by turning off both diesels and using a GE LM2500 gas turbine rated at about 25000 HP. The single turbine drives both propellers. The fuel consumption of the turbine at part load is so high, that it is worth having the diesels just for cruise power.

Peter

[Anonymous]

I have noticed a trend in European diesel manufacturers switching from single large turbochargers of the past to multiple smaller turbo chargers operating in stages. This is supposed to make turbocharging more responsive to part load conditions.

The newest trend is smaller turbochargers that are simply replacing a larger turbocharger because design advances have given the smaller unit the same capacity as the larger unit.

There have been many marine diesels built in history that are reversible and or capable of running on different numbers of cylinders. The most common mechanism for this is having the valve rockers pivot on a shaft of eccentrics that when rotated either raises or lowers the rockers onto their respective camshaft. For reversing, there may be either two separate camshafts - one for forward running, one for reverse; or a single camshaft with two sets of lobes.

[Anonymous]

QUOTE: Originally posted by Overmod

Weirdly enough, I would NOT have expected most of the crank breaks to be at the flywheel end. I'd have thought somewhere in between pairs of cylinders inducing the greatest mutual torsion... not working against flywheel inertia. I learn something every day from Randy...

Where were most of the breaks on the 16-cylinder 244s? (I've always wanted to know that!)

This isn't directly germane to *locomotive* crank breaks, but IIRC the breakage of GM truck diesel cranks is often somewhere other than at the rear main bearing. I read an account of one person with a 6.5TD who had a broken crank between the first and second pairs of cylinders. His complaint was that the engine ran a bit rough, and only seemed to make about 75% power... he was so right! Only the rear six cylinders were actually providing effective torque; the two in the front were mainly driving the auxiliaries; there was just enough interference between the two broken halves that they stayed in rough sync (think about how the injection pump wandered in and out of 'time' though, depending upon effective torsion... !)

Alco's 244 engine was rushed to market at the end of wwII because Alco was not allowed to produce a competitive road locomotive until restrictions of the war production board were lifted. It took them a while to establi***he criteria for a reliable crankshaft and also find a supplier that could consistently produce it. Other design problems in the 244 contributed to crankshaft failures, mainly the interface between the main bearing saddles and their respective caps were not designed properly, causing misalignment with wear, and thermal cycling of the block also causing misalignment problems from distortion of the block itself over time.

I do not know what that would mean as far as any trend towards the most common location of failures in a 244 crank, but can say that a failure caused by stress from misalignment would most definately be accompanied by unusual wear in adjacent journal bearings.

[M636C]

An additional problem with the 244 was dilution of the lubricating oil, this particularly affecting the crankshaft as well as the alignment difficulties mentioned by jruppert. The best indication of this is the design of the 251 engine. While on the 244, the fuel injection pumps are located in the usual place, between the valve push rods driven directly by the camshaft. In the 251, the pumps are mounted further outboard and lower down, and driven by rocker arms off the lower side of the camshaft. This location greatly reduced the risk of fuel contamination of the lubricating oil.

Peter

[Anonymous]

Jruppert: I greatly appreciate your expertise in engines -- I'm learning a lot from you and Peter that isn't really obvious in the engineering texts. But -- you knew that would have to lead to a "but" -- I don't think that War Production Board restrictions were really anything more than an excuse invented by railfans years later to explain away the failure of their beloved Alco. If one looks at the historical record when it's written by historians who don't have a pre-existing agenda to absolve Alco, it seems clear that Alco's most serious problem was that EMD had been developing a diesel engine since the early 1930s, and Alco hadn't. It was a very new and high-risk technology, and Alco waited far too late to get started. By the time they did, EMD had made all the mistakes that Alco was still destined to make, and EMD had solved them and Alco didn't even know what they'd be yet.

OS

[gabe]

QUOTE: Originally posted by O.S.

Jruppert: I greatly appreciate your expertise in engines -- I'm learning a lot from you and Peter that isn't really obvious in the engineering texts. But -- you knew that would have to lead to a "but" -- I don't think that War Production Board restrictions were really anything more than an excuse invented by railfans years later to explain away the failure of their beloved Alco. If one looks at the historical record when it's written by historians who don't have a pre-existing agenda to absolve Alco, it seems clear that Alco's most serious problem was that EMD had been developing a diesel engine since the early 1930s, and Alco hadn't. It was a very new and high-risk technology, and Alco waited far too late to get started. By the time they did, EMD had made all the mistakes that Alco was still destined to make, and EMD had solved them and Alco didn't even know what they'd be yet.

OS

OS,

Don't take this as a challenge to your position, for I am sure you are right and there is a rational explanation. But, I am curious as to the explanation.

Wouldn't GE have had an even larger technology gap to fill than ALCO since they got in the game even later and hadn't the rail background and connections that ALCO had? Yet, GE knocked off ALCO and eventually surpased EMD.

I am sure there is a rational explanation, it just isn't obvious to me.

A poster formerly known as "Gabe."

[Anonymous]

Gabe:

By the late 1950s, many of the problems that confronted Alco and EMD were moot, particularly metallurgy, and there was broad experience with light-weight, medium-speed diesel engines that did not exist in 1940. GE could purchase some of this experience, and a lot of it, such as metallurgy, they could get for free from the steel and alloy metal companies or by simply looking in the trade journals and inferring from one application into another similar application. Plus, GE had deep pockets to fund a detailed R&D project almost no matter how long it took. GE didn't need to build any locomotives to meet payroll, but Alco absolutely had to get product out the door or go broke, so Alco was really between a rock and a hard place.

GE's timing was very good. They waited until EMD, Alco, F-M, and a host of other companies had done all the exploratory work in this unknown field, but not so long that the market was completely done. The best analogy I can think of is the man who lets the pioneers go out and do battle with the Indians and the grizzly bears, and then stakes his claim on the last of the good land. Poor Alco was pretty shot full of holes by that time, but it wasn't like they had much choice. Their window of opportunity was in the 1930-1939 time frame, but I'm not even sure that even if they had seen the light on January 1, 1930 -- a light which they did not see -- that they would have had the cash flow through the depression to bring it off. GE was using its cash flow from other mature divisions to fund an expensive and risky venture into locomotives, exactly as GM had done.

OS

[Anonymous]

Does anyone else snicker when they read the title of this thread? Is the government aware of this terrible tragedy? Should Mike Wallace do an expose?

OS

[GMS-AU]

Hey , don't stop now gentlemen, this topic along with the Shells thread have really helped in my knowledge ( or lack there of ) of GM diesels as well as the other two. Here is years of collective knowledge briefly compiled into 3 pages. A humble thank you to all involved.

G M Simpson

[M636C]

If we are talking diminished power in rebuilds, since GE engines are rarely rebuilt, they must have zero power after rebuild.

But to be serious, GM purchased Winton and EMC to get their foothold in the industry, and poured money into research through the 1930s until they got to the 567 and by the time they got to the 567C in the mid 1950s, they had a very reliable engine tailored to their application.

Alco purchased McIntosh and Seymour, and got the 539, which was a pretty good example of an engine but much heavier and older in design than the 567. They put money into research and built the 241 and the 244. The magazine "Diesel Railway Traction" indicated that in England, industry insiders felt that the 244 was so much in advance of other industry practice, particularly its power rating, that it could not be true. The 251 addressed the 244's problems but wasn't a great advance. One of the features introduced by the 244, a water jacket integral with the cylinder liner, was adopted by EMD in the 567C and solved many of the problems of the 567B and earlier engines. This feature wasn't used on the 251, because Alco were going back to basics, and the Alco engines didn't need the feature as much as the EMD engines did.

General Electric weren't sitting back to the extent that the view confined to the US Domestic market might suggest. They purchased the design of what became the FDL engine from Cooper Bessemer, just as the other companies had obtained the intellectual property required to build locomotive diesel engines - buying it. The little GE 70 ton units had a Cooper Bessemer engine, the model FWL, a six cylinder in line engine, but export units had been built in the late 1940s and very early 1950s using the FVL, a V-12 version of the same engine that already had all the basic features of the FDL as used in the Dash 9s. These locomotives went to Argentina and Australia, and in Argentina particularly were thought highly enough of that large numbers of the early export U series were also purchased, some of which are still in service. At least one of the old CB engined units, a shovel nose on the metre gauge, was still running in 2003 when I visited Buenos Aires, although it had been fitted with a locally built 6-251. This showed one of the problems of the CB engine - the twelve cylinder, with the same bore and stroke as the Alco 244 and 251, could only produce 1200 HP compared to 1600 HP from the 244 at the same time. In fact, GE built a further batch of metre gauge shovel nose units for Argentina fitted with the Alco 244, as being more suited to the local needs than the CB version.

GE spent their time and money improving the CB design until it could meet the Alco and EMD engines on roughly equal terms, and released it in the U25. It is now reliably running at a significantly higher power rating than Alco ever acheived, but GE have developed another engine, the GEVO, which appears to be an improved version of the HDL engine they jointly built with Deutz. GE have proven that they can improve an engine to meet the needs of the market. We will see if it will be as good as the 710 engine GM developed from their research in the 1930s and all their experience to date.

But GE didn't start new in 1960. In Townsville in Queensland now, there is a locomotive number 1150 with a builder's date of 1951 that shared all the basic features of the U series, particularly the engine. It has been restored to working order with its original Cooper Bessemer engine, and we can be sure that GE were always aware of how this unit and other around the world, were working while they were planning the U series.

Peter