BLW 6000 was less a demonstrator and more of a testbed for Max Essl's concept of multiple small engine-generator sets. Only four engines were actually installed in the testbed since a World War was occurring at the same time, which caused various limitations and shortages.
The article describing this monstrosity is in the January 1963 TRAINS.
The original Baldwin Centipede demonstrator (described by me as a sort of 1940's era Genset) really was more like 8 750 HP locomotives on the same chassis. I can't locate the article that explained this, but it appears that the intent was to have each engine pod power one axle, but I'm sure the idea of starting and stopping individual engines never even ocurred to Baldwin engineers. It would probably have been nearly impossible with Baldwin's pneumatic controls. I think the idea was that the smaller 750 HP engines, of a design similar to the rugged VO engine used in switchers, would be easier to maintain than larger, tubocharged engines like the 608SCs used in the later versions. I think it says a lot that only four of the engine pods were built. The plumbing connections to add or remove them must have been pretty messy.
Leo_Ames And since we have single engine locomotives that are still called "Gensets", you don't even need multiple engines to be called one. So I misspoke. I think most though when they think of a Genset, they think of multiple small engines and the ability for those to matched to the job.
And since we have single engine locomotives that are still called "Gensets", you don't even need multiple engines to be called one. So I misspoke.
I think most though when they think of a Genset, they think of multiple small engines and the ability for those to matched to the job.
You know, to be honest I had always thought of 'gensets' as being multiple-engined locomotives, and what I was saying about '40s-era 'gensets' did explicitly presume that -- so Leo does not need to qualify his reply merely on that basis. This post of Leo's brings up a (possibly) important semantic issue:
Is a given locomotive a "genset" if it takes advantage of small packaged engine-generator sets, or just because it uses a small high-speed engine/generator set in place of a larger or purpose-built diesel-electric powerplant? I believe most 'genset' locomotives with only one "genset" in them are actually hybrids, like the Green Goat, that use a small onboard engine-powered generator for charging and/or peak power assist. Those are probably best considered not as 'genset' locomotives, but assisted battery locomotives, or hybrid locomotives.
(Situation might be -- not really, but semantically -- complicated because there are so many standalone generator units with 567s and 645s in them... ;-} )
Technically it is possible to build a 'genset' chassis but populate it with only one genset unit to start. It would also be possible to take the 567 out of a unit like a Geep or F unit and replace it with a genset, for example to make a dinner-train locomotive EPA compliant or more economical to keep in service. But neither of these changes the fundamental assumption that a 'genset' locomotive is designed around the assumption that there are multiple engines, and the output power of the engine is 'scaled' by controlling those engines separately -- whether via independent throttle control (automatic or manual), dropping units back to idle, or physically shutting some of them down.
The chief operational difference between the original Centipede idea and the modern genset is probably still in the design philosophy of keeping one engine/generator modlule associated directly with only one traction motor. ISTR some discussion that the locomotives, if provided initially with a reduced number of engine/generator 'modules' to give a lower power, would also lack TMs on the 'unassociated' axles. Economy by starting up and shutting down some of the engines 'in flight' was most probably not a major point, even though keeping some of them off to save fuel on a given run would have been (and starting one to replace a failed one's output would have been).
This all in turn begs a different question: Why are there no current genset engines that allow 'predictive' automatic startup and shutdown, and idling/power-modulation, control? In my opinion, any extension of the genset idea to road locomotives would almost certainly have to provide some such capability.
If this topic ought to be taken to its own post -- mods, hit it!
RME
Leo_Ames I've never seen any mention of the Centipede prototype being able to shut down and start up engines as needed. Without that feature it wasn't a 1940's era Genset.
I've never seen any mention of the Centipede prototype being able to shut down and start up engines as needed. Without that feature it wasn't a 1940's era Genset.
I had the impression from contemporary literature that the individual drive was intended for reliability in cases of road failure, and adjusting available power to train characteristics at the start of a given run. From what I understand, though, current designs of genset are not designed to fully start and stop engines based on actual load, although there are controls allowing separate loading/idling, so the comparison is not as dismissible as it may appear at first. That functionality would be relatively simple to add to a Centipede, as you'd only need to interrupt the throttle rack opening and generator field on a selctable-individual-engine basis. (This might well be electrical rather than pneumatic, because no proportionality is required, but you would need some sort of dashpot to prevent excessively quick throttle response when individual engines were cut in with the locomotive at high speed or load.) I would NOT expect any early expectation of MUing 6000 HP locomotives together in the early '40s, even if Baldwin weren't working off analogy with single-locomotive-headed consists a la steam. If MU were to be combined with individual control over 8 engines per unit ... well, actually, the EMD 'digital' logic system (with three 'bit states') would have worked because at least one engine per locomotive would have to stay running at all times, so you could easily 'isolate' in pairs, triples, etc. even without addressable switches and cables for each individual engine in multiple units...
These things would NOT be used in switching, so very little benefit in full demand-based on-the-fly startup/shutdown. Even if the coolant loops were interconnectable to keep a chosen set of engines hot, and oil systems on that set were all interconnected and acting as prelubers for the shut-down engines, I doubt that automatic cranking and shutdown on that number (and relative size) of V-12s or V-8s would be particularly practical or safe with the technology of the early Forties. If I remember correctly, the sets were transverse and took up most of the available carbody width, so no longitudinal corridor to reach the individual engines easily for manual starting while moving.
When the design was re-engined with inline motors there was plenty of room for passage, but of course no particular reason for select-a-power of any kind. There was little of that reliably available in the first place... ;-}
Yeah, as far as I know none of them had dynamic brakes.
It created a dilemma for the Pennsylvania when the Fall traffic rush of 1958 hit and they were unexpectantly returned to service after being stored several months earlier. Maintenance had been neglecting their many brake shoes since there were so many and they were a pain to replace since a large diesel order that was planned to kill the last of steam during traffic rushes was expected to keep these from ever being needed again when a recession struck and reduced traffic requirements. So minimum work had been being undertaken in recent months.
But return they did and the brake shoes were in horrible shape due to their heavy usage due to the lack of dynamic brakes and subsequent neglect when it was thought they were done for soon. There's first hand information in Trains Magazine of their reactivation and subsequent usage of some members into 1962 when they were retired so I think that's reliable information. What I don't know is just how many survived in active service into that final year.
My guess is that the photo you saw was indeed one of the two that was retired early in Mexico. I've never seen the reasons explained why they didn't get rebuilt along with their sisters so crash damage makes perfect sense. I imagine the other unit also was seriously damaged and considered not worth rebuilding either via a wreck or a particularly bad fire.
My Centipede retirement dates come from this publication and were compiled by Kenneth L. Douglas with assistance from David H. Hamley. I can't personally attest to their accuracy.
I have different dates for the SAL units in different orders, though all mine show 1959 and 1960 dates. Our NdeM information matches. I had conflicting reports regarding PRR's last time used, though have the 1962 retirement date from several sources. It was towards the middle of the 60s that NdeM's started staying strictly between Saltillo and Carneros to serve as head-end helpers. As we've both noted, they went from 10 in 1964 to 3 by 1967. (It's the ten still in service in 1964 that I have models of. 6400-6406, 6410, 6411, and 6413. Thank you Broadway Limited, even though they have the Pennsy carbody.)
Mexico's Centipedes were rebuilt by Baldwin starting in 1953 which is when they received their new "Mexican hat" piston design and improved turbochargers that resolved most of their issues. They also lacked dynamic brakes which along with their inability to MU saw them gravitate to helper service where their high tractive effort could be put to good use and those drawbacks didn't matter as much.
And while a large new locomotive order and a recession saw Pennsy's Centipedes stored in 1958, many came out that Fall again and several stayed active into the 60's. Retirement came in 1962 and some units were still active when that came.
Beyond reliability (Which was poor and saw Pennsy derate them), several significant mechanical issues, inability to MU with other power and lack of nose connections, and the lack of dyanamic braking, another significant issue with Pennsy's were the drawbars which meant that only Juniata's backshop could handle maintenance on them and roundhouses couldn't accommodate them due to the length.
Retirement dates for SAL's Centipedes show as 1961 for the 4500, 1957 for series 4501-4505, and 1961 for 4506-4513. For Mexico, I show two being unrebuilt and retired in 1954, two being retired 1961-1962, seven from 1964-1967, and the last three in 1971.
It's correct that only the middle eight axles on the centipedes were powered, however provisions wer made to power the other four axles for a "freight only" version. Both pilot and trailing truck had mounts for traction motors for a DR12-12-1500/2. Seaboard Air Line's were retired in 1959 and 1960. Most of Pennsy's were out of service in 1958 but actually not scrapped until 1962. NdeM 6400-6406 and 6409-6413 were rebuilt about this time. 6409 and 6412 would be gone by 1962, and all but three of the others were gone by 1967. 6401, 6402 and 6405 would serve NdeM until 1971. (Which leaves the tantalizing possibility that at one point, one locked knuckles with something as new as a GP38 or an SD40. Photos exist of them with C424s. NdeM had better luck with their units for serveral reasons. They had patient, persistent, highly capable and resourceful shop crews (which helped many an oddball locomotive survive). They also placed the units in service that played to their strengths. (Pennsy made the baffling decision--at one point--to attempt using them to shove cars over a classification hump--which gave them lots of practice at rerailing centipedes.) SAL's were able to run with other units AFTER SAL rebuilt them with EMD-style electric throttles. (Baldwins came with a pneumatic throttle as standard equipment, which was why most could not MU with other builders' units. This trait was a leading factor in dooming their locomotives to an early scrapping. Baldwin would later offer an electric throttle as an extra-cost option.) NdeM also ran trains suited to the use of a single centipede as power and also as manned head-end helpers between Saltillo and Carneros, both assignments that rendered their incompatibility with other units a moot point.
While there was a rampant fear among the railroads that the unions would demand a crew for each locomotive, there were no contracts that required this. Fortunately unions accepted the precedent set by traction companies (interurbans) and agreed any number of MUed units required only one crew. The centipede's design was based on the possiblity the unions might make a demand that each unit have a crew.
Labor contracts did not specifically mandate a crew for each diesel unit but management at the time did fear grievances over this issue. This was the rationale for the letter suffixes on booster units and one road number for four-unit FT sets.
Only the middle eight axles were powered on a centipede. The first one was built as a Baldwin demonstrator which was sort of an early genset unit, which was supposed to have 8 750 HP transverse engine/generator modules (it only ever got four) for 6000 HP with the imposing model number DR-8-12-750/8 which indicated 8 powered axles (out of 12) with 8 750 HP engines. The prototype didn't work out so the frame was re-used on the prototype for the production type DR-8-12-1500/2 which had a pair of 608SC engines for 3000 HP. Seaboard and NdeM got single unit versions (Seaboards's would multiple with other makes - not common with Baldwin models) and PRR got two-unit drawbar-connected versions. None were particularly successful, though Seaboards an NdeMs' had a fairly long life, improved after Baldwin developed the "Mexican Hat" piston (after its shape, not NdeM) to fix a chronic problem with turbo failures due to unburned fuel.
The rationale was based on 1930s electric locomotive design (think GG1) and on union contracts that did not allow treating MU consistes as a single locomotive. Changes in law and contracts would have done the centipedes in even without Baldwin diesels' poor performance and high maintenance cost.
This locomotive had powered axles under it almost all the way from front to back. Nobody else built a diesel like that. Someone at Baldwin thought this was a good concept. Can anyone tell me what the rational was for doing it this way? I was just curious. I never saw one of these in service.
George
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