Make that "almost any" engine. While they won't be hauling mainline coal trains, geared locomotives powered the entire locomotive and tender, with no leading or trailing axles and no non-powered trucks under the tender.

In fact, I tend think of them as the steam version of a typical diesel electric locomotive. All axles are powered (excepting a-1-a diesels), the trucks do not have a long rigid wheelbase, and they can flex to better accommodate rough track.

From a wheel/rail interface point of view, there's really not much difference between a 2 trucked gear locomotive and a diesel electric.

Granted, it's not something that can be used for high speeds, so it's pretty irrelevant to this discussion.

Conventional locomotive tenders have been powered before, but it wasn't something that worked very well, as those who know history will recall from these examples:

http://www.douglas-self.com/MUSEUM/LOCO ... ttshay.jpg

http://i149.photobucket.com/albums/s63/ ... lex1sm.jpg

http://www.douglas-self.com/MUSEUM/LOCO ... n28884.jpg

I couldn't easily find any photos of them, but Southern Railway for a while had some locomotives of various types, mostly 2-8-2s, with what were called "tractor" tenders, which used the running gear of old 2-8-0s. These, and the Triplex locomotives, could all be characterized as having "too many wheels and not enough steam." It is useful to remember that pistons, rods, and wheels are all really transmissions in a steam locomotive; the real source of power is the boiler, specifically the firebox. Any fireman on a hand-fired locomotive would quite forcibly remind you of that!

I do seem to recall there was a proposed variant of the ACE 3000 that would have had a powered "tender," utilizing a second set of running gear close to if not identical with the first. Operationally it would have been comparable to a high-powered diesel and a slug--lots of tractive effort, but speed would be down considerably.

It's a reminder of how one can use horsepower (rather than just tractive effort), either to drag or to run, at least within certain ranges.

And there have been some interesting proposals regarding how to do just that with modern steam locomotives. We've previously discussed some of these.

The original V1 turbine was not very different (although using long 'engine beds' rather than span-bolstered trucks.} It bears noting, perhaps, that the siren call of motoring the lead trucks (the V1 essentially had two!) led to N&W adopting individual-axle electric-traction-motor drive (and this after the experience C&O had with its own steam-turbines!). As a peripheral note: I believe this would likely have foundered on the same rock that took the PRR P5b 4702 -- the relative inability to provide effective traction-motor blower cooling. It bears noting that N&W in the event DID go to span-bolstered trucks, and one of the great bugbears of the TE-1 turned out to be the TMs...


> In fact, I tend think of them as the steam version of a typical diesel electric locomotive.
> All axles are powered (excepting a-1-a diesels), the trucks do not have a long rigid wheelbase,
> and they can flex to better accommodate rough track.

All of which are good. Not so good is the required boiler offset, relatively narrow firebox, and one-sided drive necessary to get shafting aft of the firebox. Getting around this problem, as on the V1, requires two motors or a relatively high grate with divided ashpan.

As has been noted previously, perhaps the 'best' design would use the truck design of the Climax with the centerline drive of a Heisler, with multiple cylinders in the engine (probably a double-acting V4, which can be made inherently in balance for our purposes). It is interesting just how large a boiler can be provided above this running gear and still fit in typical loading gage... there is also relatively little restriction on how fast the running gear can be worked, up to sensible mainline speeds.


> From a wheel/rail interface point of view, there's really not much difference between
> a 2 trucked gear locomotive and a diesel electric.

There is an enormous difference, in favor of the steam locomotive. Diesels have a great deal of unsprung mass, carried down very low, with limited lateral compliance. That makes them track punishers in a number of very significant respects. A modern 'geared-ocomotive' truck can be made little different from a monomoteur or diesel-hydraulic truck, with all the high-speed stability advantages that implies.

We could also mention high-speed braking, but that is going outside the scope of what is already very nearly a digression.


> Granted, it's not something that can be used for high speeds, so it's
> pretty irrelevant to this discussion.

Only if you're talkin' Shay. Now, even there, asymmetrical design does not necessarily spell doom -- the German motor locomotive 19 1001 design has the V-motor drive on one side of the axle, and this design would be reasonably suitable to use for 'motor tendering' something with a straight chassis. (The same might be said for the Besler motor drives from the stillborn B&O W-1, but I shudder a bit to think of maintaining those things under a tender cistern... ;-} )

The chief issue with geared locomotives at high speed is how you protect the gearing. If ballast is flying around, you're not going to be able to tolerate open gearing very long -- one way or another! -- and the cost of making and servicing the enclosed drivelines may not be competitive with the simple Crater-filled gearcases of nose-suspended motors. Scaling up the kind of drive that worked on RDCs did not pan out for Krauss-Maffei or Alco in the '60s, although I would welcome an operational discussion of those things [note: relevant on a preservation board because of the excellent efforts of the team at CSRM with the 'ex-camera-car' -- if you are unfamiliar with this, go see what they have accomplished with a restoration done all the RIGHT ways...)

K-M loco SP 9010 is being restored by the Pacific Locomotive Association.

Dave

Thank you.

The work deserves full credit to all concerned.

I would think the main issue with speed-shays would be the driveshaft line being NOT on the centerline, thus requiring excessive telescoping in curves.

As far as driveshaft durability, carbon fiber works wonders in a couple of ways. First it is freakishly lighweight, secondly, it shatters instead of bends when it exceeds design strength.