USRA 2-6-6-2 Review needed

[SteamGene]

Isambard, you have it backwards.  The Spectrum model is of the USRA light Mallet - 2-6-6-2, which is the C&O class H-5, not the H-6 or almost identical H-4.  The USRA light is smaller than the USRA heavy, 2-8-8-2, which is the basis of the N&W Y class.  You are correct that the C&O H-4/6 was not a USRA design. 
Gene

[Atlantic Central]

Interesting,

I posted a similar reply to Isambard just before the site went down Monday night, I guess it got lost in the crash.

Sheldon

[Isambard]

Isambard, you have it backwards.  The Spectrum model is of the USRA light Mallet - 2-6-6-2, which is the C&O class H-5, not the H-6 or almost identical H-4.  The USRA light is smaller than the USRA heavy, 2-8-8-2, which is the basis of the N&W Y class.  You are correct that the C&O H-4/6 was not a USRA design. 
Gene

Thanks for the clarification Gene. Know any places where I can find a photo or details of the USRA light 2-6-6-2/C&O H-5?

[SteamGene]

C&O never did anything to their H-5s.  They didn't like them - probably because they were so close to the H-4/6!  The loco came with smokebox mounted pumps and C&O never changed the cab or the tender.  If you take the small cab off a Riv H-8 and the 16V tender you have a reasonable model of the H-4/6.
You can find photos of the C&O H series by googling "fallen flags."
Gene

[Isambard]

--Another problem with this loco is that the pilot is very low, actually rubbing on the railheads, with the result that the front coupler is also too low.  While this doesn't appear difficult to remedy, I was wondering if this problem is a common one, with a "stock" way of making an easy repair. ---

Wayne

The pilot  on my 2-6-6-2  (footboards with small boiler tube centre section) clears the railhead by about 1/16 in. and the coupler is about 1/32 in high to the Kadee coupler gauge. Thes dimensions vary a bit, depending on whether the loco is moving forward or in reverse, this affects the load on the front engine and its longitudinal tilt relative to the track, as the front engine is very flexible in all axes.

The looseness of the front engine doesn't appear to be a problem, however I have noticed a tendency for it to derail on uneven track or switches as the front engine loses rail contact with the loco running forward and with a load behind. 

[lanny]

doctorwayne,

That is a very nice looking 'Connie' you have modeled and weathered. The whole photograph is really nice, very realistic looking scene.

Show us your 2-6-6-2 when you get it done and keep up the great modeling work!

lanny nicolet

[amdaylight]

After reading this whole thread I have a few things I would like to point out. First if the locomotive is a true Mallet and not just a simple articulated locomotive, the way to tell them apart is the size of the pistons. If one set is larger than the other then the locomotive is a true Mallet and will not have the syncopated sound of the simple articulated locomotive. The reason is there is only one set of exhausts coming from the front set of drivers. The rear cylinders are the high pressure ones and their exhaust is routed to the front or low pressure cylinders. Most of the Mallets could be operated in simple mode where both sets of cylinders received high pressure but his was only for starting the locomotive due to the difference in power the larger cylinders would put out. If you did not start them in simple mode the rear drivers would have to slip two or three revolutions before the front cylinders received any steam. Some railroad crews did refer to both kinds as Mallet’s but this was incorrect. Now as to the tank versions of the logging Mallets that Mantua builds, these were road engines for the logging railroads and had runs of 75 to 100 miles which is comparable to the mainline divisions of about the same length. The reason that they could go so far with out a tender is the fuel that they burned, oil. Usually two thirds of the saddle tank was water and the last third was fuel oil these percentages match tenders pretty closely. Most if not all of the western loggers used fuel oil for several reasons, first it did not have embers and sparks to light the woods, mill and other things on fire, two it was easy to store and it was easy to load into a locomotive, just pump it into the tank or pour in like water if it was heated. The tank Mallets had built in tank heaters with the tank sitting on the boilers but this causes another problem, the injectors don’t like warm water so it was some time a little difficult to get the injectors to work. One reason the logging railroads liked the 2-6-6-2T was that they ran backwards at a higher speed than the tender engines pushing their tenders

I know this kind of long winded but I thought some one might be interested.

Andre

[SteamGene]

Andre, the C&O H-1 through 6 were all Mallets.  The H-7 (2-8-8-2) was a simple and called by its crews the "Simple Simeon."  The H-8 (2-6-6-6) was also a simple. 
Gene

[amdaylight]

Gene,

Thanks for the reply, I learned something new today.  As I am on the west coast and have not studied the eastern articulated locomotives and did not know how the eastern crews referred to their locomotives. I do know the SP crews referred to the cab forwards as Mallets (and some referred to them as “Backwards or Backup Mallets”) even though only the first couple of orders were built as Mallet’s and they were converted to simple engines after about 10 years as the SP need more speed out of them. Most of the logging lines called any thing that was articulated a Mallet weather it was or was not, this I can kind of understand as the vast majority of them were Mallets.

My comments were more aimed at the sound question as people were expressing the fact that they liked the sound as each engine on the locomotive came in and out of sync with the other one. This would not happen due to the reuse of the steam by the low pressure cylinders and only one set of exhaust instead of two as with a simple locomotive and what was and was not a road engine.

Andre 

[JimA]

...two USRA 2-6-6-2s, and one Mantua logging 2-6-6-2.  They all have that characteristic in and out of syncopation business programmed.  An articulated would sound strange any other way...

Hmm...  I thought only simple articulateds (e.g., a Challenger, Big Boy, or N&W A-class) went in and out of syncopation.   I would think a true mallet (which I believe the USRA 2-6-6-2 should be) would have its engines synchronized in a regular fashion...  after all, the low pressure (front) engines are fed directly from the high pressure engines' exhaust.  How could the phase relationship of the engines ever change?

Or am I confused?

--Jim

[Atlantic Central]

JimA,

All articulated locos go in and out of syncronization. Since there is no mechanical link between the the two engines there is nothing to keep them in sync, and the combination of curves and slippage will always change their relationship to each other.

The main point that almost everyone misses about this is that the steam on the intake side of the valves is in a plenum or manifold, just like the fuel mixture in a car engine. The steam "waits" there until it is needed by which ever side of which ever piston opens its intake valve port next. This is true of Mallets or simple expansion machines.

The only difference being if it is comming from the boiler or from the exhaust of the other set of pistons, and that controls the sound issues. The the sound system of a Mallet should be in syync with the front engine.

Sheldon

[morrisf]

This is from Baldwin info from years ago:

Attention should be given to the slipping of the driving wheels in a Mallet locomotive. If the wheels of the forward group slip frequently, while those of the rear group do not, it is an indication that steam is leaking past the high-pressure valves, and these should be examined for blows. If the valves are in good condition, and the wheels of only one group slip, the unbalanced pressures resulting will tend to stop such slipping. Any continuous slipping can occur only in both groups of wheels simultaneously, and should be corrected by throttling the steam and using sand.

More can be found at

http://www.catskillarchive.com/rrextra/blwmal00.Html



Morris

[Isambard]

Gene,

Thanks for the reply, I learned something new today.  As I am on the west coast and have not studied the eastern articulated locomotives and did not know how the eastern crews referred to their locomotives. I do know the SP crews referred to the cab forwards as Mallets (and some referred to them as “Backwards or Backup Mallets”) even though only the first couple of orders were built as Mallet’s and they were converted to simple engines after about 10 years as the SP need more speed out of them. Most of the logging lines called any thing that was articulated a Mallet weather it was or was not, this I can kind of understand as the vast majority of them were Mallets.

My comments were more aimed at the sound question as people were expressing the fact that they liked the sound as each engine on the locomotive came in and out of sync with the other one. This would not happen due to the reuse of the steam by the low pressure cylinders and only one set of exhaust instead of two as with a simple locomotive and what was and was not a road engine.

Andre 

The discussion as to what constitutes a Mallet continues all these years after the last ones, "true" or otherwise, have gone to the scrappers, museums or preservation societies. Certainly Anatole Mallet received a patent for a compound articulated locomotive, however I recall a British writer in LocoProfile argued that Anatole Mallet should also be given credit for the fixed simple articulated, and referred to the simple type as "Mallets".
Alfred W. Bruce (American Locomotive Company) in his "The American Locomotive in America" states "The term Mallet should be used only to designate articulated compound locomotives". Perhaps he was simply being academically correct, but then perhaps there was a patent Royalty issue lurking somewhere? 

[robman]

Rich,

Not to hijack this thread, but how do you like your Mantua?  Especially compared to the Bachmann?  Micro-Mark has one of those babies for sale, too, although it is a 2-6-6-2T.  Both can negotiate 18" radius curves.

Too, that birdshot in a balloon is a neat trick!

Why could you not cast a TBSP of lead, or similar size, then trim it to fit a sand dome, etc? Sheldon mentioned moldable lead. I presume this is similar to Al foil, and "scrunchable?"

Best, Jack

[robman]

Just wanted to add that I sure agree with Sheldon about making sure your rolling stock is 'free rolling'!

That was one of the first great lessons I learned on this forum ... what a 'reamer' was and the benefits of using one.

My personal favorite combination is reaming all delrin trucks (not metal ones ) with a Micro Mark 'Truck Tuner' or a Reboxx 'Reamer'. Then I use Intermountain 'semi-scale' metal wheel/axles. As Sheldon has pointed out, this probably is the best way to increase 'pulling potential' for most HO locomotives.

I might add that in my personal tests of 'before' and 'after' distances freight cars roll, using the 'reamer' and the adding the Intermountain metal wheel/axles in general increases the rolling distance of my cars 3 1/2 times the distance they originally free rolled.

lanny nicolet