Going back to Allen's question (two postings back), it has not been a smooth ride for eight cylinder engines in the locomotive size range. EMD had a number of problems with their eight, not so much in locomotives as in power generating service where the engines have to run at synchronous speed (generally 720 RPM or 900 RPM depending on the type of generator) continually. EMD uses very large camshaft counterweights rather than balance shafts to provide the necessary balance solution for their engine, and many of the earlier eight cylinder crankcases had problems with cracks developing in the end sheets around the counterweights. This peaked in the early 645 production when most of the generating applications went to 900 RPM (567's had generally been run at 720). There were a series of modifications issued to increase the bolting and doweling of the camshaft bearing supports, and finally they adopted a heavy crankcase design with much thicker end sheets.
I can't speak much for GE's experience with their eight cylinders, there were not enough of them out there that I encountered. However there is one very significant difference between the EMD and GE design practices and the ALCO 251 arrangement. In EMD and GE engines the cylinders are directly across the engine from each other and apply the connecting rod load at the center of the crankshaft journal, in the ALCO 251 the cylinders are offset bank to bank, so that the rods from opposing cylinders seat on the journal next to each other. This imposes a rocking force couple to the loading on the crank throw in addition to the usual reversal of force you get on the crank journal of a four stroke cycle engine due to the intake stroke. It adds one more complex element to the design process.
I apologize again to those who want a "pure" forum, for talking about non locomotive applications. But as I have pointed out before, if you only look at the locomotive side of the business you only get part of the story.
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- Discussion of products from the American Locomotive Company. A web site with current Alco 251 information can be found here: Fairbanks-Morse/Alco 251.
Moderator: Alcoman
Mxdata--
You don't have to apologize to ME for bringing in stationary and marine applications! My interest, here, is railroad-centered, but I think my understanding of railroad and locomotive history would be impoverished if I didn't know about the larger technological context. And I have found your posts very interesting.
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On a substantive matter... It occurs to me that, if I had remembered, I would have known that EMD had problems with the 8-567. The 8-567C had vibration problems not experienced with other 567C models, and (??2 or 3 years into 567C production??) the firing order of the cylinders was revised. Engines with the revised firing order were known as 567CR. (There is a 567C maintenance manual among the operator's manuals on George Elwood's "Fallen Flags" railphoto website, listing the old and new firing orders.)
You don't have to apologize to ME for bringing in stationary and marine applications! My interest, here, is railroad-centered, but I think my understanding of railroad and locomotive history would be impoverished if I didn't know about the larger technological context. And I have found your posts very interesting.
---
On a substantive matter... It occurs to me that, if I had remembered, I would have known that EMD had problems with the 8-567. The 8-567C had vibration problems not experienced with other 567C models, and (??2 or 3 years into 567C production??) the firing order of the cylinders was revised. Engines with the revised firing order were known as 567CR. (There is a 567C maintenance manual among the operator's manuals on George Elwood's "Fallen Flags" railphoto website, listing the old and new firing orders.)
Yes, indeed. I had not thought of including that detail in my earlier posting. Thanks for the reminder.
Alcoman's earlier question about a ten cylinder version of the 251 is a very interesting one. I am going to have to think about that for a while. I do not know what other ten cylinder diesels might have been produced with a comparable Vee angle, that would give a clue as to how practical it would be. Due to railroad size diesels usually being a much shallower Vee angle than smaller automotive applications (to keep the hood width to a minimum and allow for easier removal of reciprocating components), the crankshaft torsional solution might be rather challenging.
Unfortunately all the people I knew who worked directly on the 251 design project have passed away now. (It was of course 55 years ago when they did the design work).
Alcoman's earlier question about a ten cylinder version of the 251 is a very interesting one. I am going to have to think about that for a while. I do not know what other ten cylinder diesels might have been produced with a comparable Vee angle, that would give a clue as to how practical it would be. Due to railroad size diesels usually being a much shallower Vee angle than smaller automotive applications (to keep the hood width to a minimum and allow for easier removal of reciprocating components), the crankshaft torsional solution might be rather challenging.
Unfortunately all the people I knew who worked directly on the 251 design project have passed away now. (It was of course 55 years ago when they did the design work).
"We Repair No Locomotive Before Its Time"
mp15ac wrote:No, all of FM's engines were inline opposed piston designs (with a few minor exceptions).Not true. Like many engine manufacturers FM made quite a variety of engine types. For FM two types were opposed piston, and one of those were used on locomotives. The other OP engine was, and is, routinely used for auxillary power on ships.
Stuart
One shortcoming of the 244 which could not be corrected is the routing of the high pressure fuel line from the pump to the top of the injector. The line is an unsupported U shape within the cylinder head cover. Harmonic vibration can cause the line to snap at either end, allowing fuel to mix with the lube oil and drain into the crankcase. Lube oil dilution would generally cause bearing and/or crankshaft failures before the low lube oil pressure relays cut out and killed the engine. Both the 241 and 251 were designed so that a broken fuel line would drain outside the engine, a generally accepted safety feature. EMD's fuel lines are within the top deck but don't seem to be as failure prone, perhaps due to short unsupported runs and low pressure.
Steinbrenner's book on Alco has the most in depth description of the testing of the 241 engines I have read. He reports that the engines were equipped with experimental cast iron crankshafts which failed. The first 12-244's for GM&O also had cast iron crankshafts. All had to be replaced with forged cranks at Alco's expense.
My candidate for "ugliest" Alco? Any RS-2/RS-3 that had not been repowered with a 12-251.
Alex Huff
Steinbrenner's book on Alco has the most in depth description of the testing of the 241 engines I have read. He reports that the engines were equipped with experimental cast iron crankshafts which failed. The first 12-244's for GM&O also had cast iron crankshafts. All had to be replaced with forged cranks at Alco's expense.
My candidate for "ugliest" Alco? Any RS-2/RS-3 that had not been repowered with a 12-251.
Alex Huff
The two top deck fuel lines in the EMD engines are indeed under very low pressure, the supply line is normally no more than 60 PSI, governed by the bypass relief valve. The other line is a bypassed fuel return to the tank. In four stroke cycle engines in the 1940s, the high pressure line between the injection pump and the nozzle already carried several thousand PSI impulse pressure at full rack. Nowadays the peak fuel injection pressures in four stroke cycle engines with separate pump and nozzle are getting even higher, I have heard some figures up around 18,000 PSI peak injection pressure on recent production engines.
The improvements in the fuel system design of the 251 (as compared with the 244) got mentioned in the early 1950s ALCO sales brochures and their technical papers, which is a pretty good indication that the customers were well aware of the problem with the 244s. Having to compare an improvement in your product with the performance of your previous product is not necessarily a good thing. You would usually prefer your advertising space be spent on the advantages your new product has over competitors designs.
The improvements in the fuel system design of the 251 (as compared with the 244) got mentioned in the early 1950s ALCO sales brochures and their technical papers, which is a pretty good indication that the customers were well aware of the problem with the 244s. Having to compare an improvement in your product with the performance of your previous product is not necessarily a good thing. You would usually prefer your advertising space be spent on the advantages your new product has over competitors designs.
"We Repair No Locomotive Before Its Time"
I think the failure mode on 244 hp fuel jumpers was not just a case of straight vibration induced failure. In Alco literature relating to both the 244 and 251, there are a number of references to something called the "snubber valve"-a check valve actually retrofitted to 244's and made standard on the 251.
BTW, the New Haven RR seemed to avoid the entire issue with 244 engine lube oil dilution by performing a 15 day inspection on the locomotives, along with a simple check of lube oil viscosity with a "Visigauge."
Yet another allusion to problems with 244 engines seems to be the ongoing mention in Alco literature of the four engine mounting feet being located at the "nodal points" on the 251. On the 244, two of the engine mounting feet were located on the generator adaptor-which was a separate assembly. The 251 dispensed with this part.
BTW, the New Haven RR seemed to avoid the entire issue with 244 engine lube oil dilution by performing a 15 day inspection on the locomotives, along with a simple check of lube oil viscosity with a "Visigauge."
Yet another allusion to problems with 244 engines seems to be the ongoing mention in Alco literature of the four engine mounting feet being located at the "nodal points" on the 251. On the 244, two of the engine mounting feet were located on the generator adaptor-which was a separate assembly. The 251 dispensed with this part.
I think the failure mode on 244 hp fuel jumpers was not just a case of straight vibration induced failure. In Alco literature relating to both the 244 and 251, there are a number of references to something called the "snubber valve"-a check valve actually retrofitted to 244's and made standard on the 251.Interesting you bring up the snubber valve. This was used to reduce stresses caused by the injector pulse. EMD injectors are either MUI or EUI, (mechanical or electrical unitized injector) and fuel delivery pressures are developed in the injector unit it self. When EMD first came out with the EUI, they used the standard low pressure steel fuel return lines and an interesting thing started to happen...the lines would erode from the inside out. It was determind that there was a reversion pulse created by the injector opening and closing, thus creating a shock wave inside the fuel return lines. When EMD was trying to overcome the return line failures, it was suggested that the solution could be found by using an Alco style snubber valve. Of course this was rejected by the EMD engineers. The eroding fuel return lines was solved with the use of steel braided lines that could absorb the shock wave.
Paul
"We are all here because we are not all there."
"We are all here because we are not all there."
As for ugliest locomotive I would have to say that some of those hammerheads were pretty ugly, with that raised short hood.
Interesting reading. I'd have to agree with most of
the observations. Never worked as a diesel
mech but did with airplanes. Airplanes get
the once over every 25hrs. THings like fuel
dilution, leaks of coolant
as well as lube, broken belts, just about
any sqawk from the incoming crew is caught
early on. Oil sampling is a big thing too.
If an engine is annoying to work on or is
perceived to be so, then it likely will get
less than good treatment unless the shop boss
is on top of things.
Human nature at work.
There are still 244 engines at work today.
Flawed in design, requiring more
diligent care than the EMD engine they
still are a functional design.
But it is all a business and if it is
cheaper to run the shop with less men
and run the locos into the ground then
that is what will happen.
Maintenance force is expensive, equipment
that needs less is the way of the future.
Heck, my last set of plugs in my truck
went 127k. I could have regapped them
but since I didnt bother for the last 127k
I just tossed in a new set which will
last until the old shoe becomes fodder
for a Chinese mill.
...typical mechanic, eh?
the observations. Never worked as a diesel
mech but did with airplanes. Airplanes get
the once over every 25hrs. THings like fuel
dilution, leaks of coolant
as well as lube, broken belts, just about
any sqawk from the incoming crew is caught
early on. Oil sampling is a big thing too.
If an engine is annoying to work on or is
perceived to be so, then it likely will get
less than good treatment unless the shop boss
is on top of things.
Human nature at work.
There are still 244 engines at work today.
Flawed in design, requiring more
diligent care than the EMD engine they
still are a functional design.
But it is all a business and if it is
cheaper to run the shop with less men
and run the locos into the ground then
that is what will happen.
Maintenance force is expensive, equipment
that needs less is the way of the future.
Heck, my last set of plugs in my truck
went 127k. I could have regapped them
but since I didnt bother for the last 127k
I just tossed in a new set which will
last until the old shoe becomes fodder
for a Chinese mill.
...typical mechanic, eh?
I heard the C636 were horrible units even some of ALCo's best Custmores hated them.