Have any of the locomotive companies made an articulated diesel? Like a DD40x but bendy. Would it make maintainance any easier?
While not actually articulated, The New Zealand Railways 1000 HP DJ class, built by Hitachi (I think) had three two axle trucks with the centre one free to move laterally in curves.
A couple of these are preserved on the Taieri Gorge Railway, and the running through curves feels a bit odd with all the trucks moving a little.
The Trains tour in October will be going there.
Of course, with a truck where the fuel tank should be, you have to find somewhere else for the fuel.
M636C
I think that is what we see on almost every train these days… two Dismals connected together, but they don’t bother with a drawbar between them, just use normal couplers, makes maintenance so much easier to be able to replace the half in need of maintenance and keep the other half in service.
The Baldwin centipedes were articulated, but most diesels used individually pivoting trucks.
and you saw how popular those weren’t, powerpacks and all on top of a custom wheelset more attuned to electrics or steam engines.
GM’s early road diesel, the FT, was often built in A-B sets connected with drawbars.
More parts, espicially moving or “bendy” parts, mean more maintenance and repairs.
To me - drawbar connected and articulated are totally different animals. Articulated is two carbodies sharing a common truck at their coupling - the original Zephyrs were articulated.
EMD’s TR-model locomotves were, as far as I know, all drawbar-connected “cow-and-calf” locomotives. It made more sense to replace the drawbars with ordinary couplers, but I know that one of CGW’s TR2s had drawbars as recently as 1971, when I worked with it (others had been separated).
But there was rarely a need to produce a diesel in a long-enough carbody that had to be kept straight, as was necessary for a steam locomotive’s firebox/boiler/smokebox assembly.
GE made the U50 for UP. It had B+B-B+B wheel arrangement. The span bolster trucks apparently came from earlier gas turbine engines.
Articulation just means a flexible joint. Car bodies sharing a common truck is one type of articulation. Some steam engines and early electrics, as well as the Centipededs, had articulated frames.
This could be a future Trains article: early, oddball and articulated diesel locomotives. In the 70s as a child I thought that they could make a diesel/pneumatic locomotive. I was thinking of a lot of things as a child in the 70s: opposed piston engine, as in two Pistons per cylinder facing each other with two crankshafts linked via gears. My engineer brother looked it up and it turned out to be a Fairbanks Morse.
Wasn’t the SF-1 (1st motive power for the Super Chief) described as an articulated? I’m not sure if that means permanently coupled, drawbar, or what.
Some of UP’s M1000x sets had drawbars between units. AT&SF 1 and 1A (original EMC Super Chief power) had couplers on both ends.
I was going to say that I’d take that a step further and say that articulated means two parts that must be flexible but cannot be separated without making both useless. That would include consists where a truck is shared between two cars.
But that would include today’s intermodal “cars,” which do just that. I can’t say that I’ve heard them called articulated.
I must exclude from that steam locomotives and tenders, and B units.
I think most folks think of articulated as a something that could be one, but is made into two for sake of flexibility.
That was already done in the 1920s. in “Dawn of the Diesel Age” Kirkland shows photos of some of the alternate transmissions tried. Pneumatic, direct gearbox (3 speed no less! keep your foot off of the clutch), siderods from the crankshaft and probably one or two I am forgetting.
The AT&SF experimented with articulated steam locomotives where the two frames were rigidly attached to the boiler, but the boiler itself articulated by the hinge effect of a bellows connection in the boiler barrel. See Figure 4 here:
http://www.catskillarchive.com/rrextra/blwmal00.Html
With a diesel locomotive, D-D trucks are likely to be too long to negotiate curves, so each truck must be articulated. One way is to use two B-B trucks with a span bolster, and then connect the center of the span bolster to the center bearing of the locomotive frame. This is common on Brazilian locomotives such as shown here:
http://www.thedieselshop.us/BrazilLocos.HTML
True , but note that one of the major Brazillian operators of Bolster connected BBBB trucked units also rosters SD45 variants with DD trucks so both designs work for them…
Yes, as designed and first produced, there was no provision for couplers between the A and B units, only a drawbar. There wasn’t even a door you could close between the two units. A railroad could buy an A-B or A-A set with drawbars. ATSF wanted the flexibility of having couplers at both ends, and EMD was able to rig up a coupler to fit in the space for the drawbar.
Many railroads bought, numbered, and operated F units in A-B-B-A sets, often with drawbars between the A and B units. The units were thought of as parts of one engine, and the four unit set had roughly the same horsepower as a typical Mallet articulated steam engine of the time.
BTW many early diesels were serviced in steam-era roundhouses, and an A-B set of F’s would fit on a typical turntable, but not an A-B-A or A-B-B set.