2-6-6-2 Sound phasing

[RRPETE]

Just got the new 2-6-6-2, and am curious about the chuff sound phasing. I was expecting the chuffs to go in an out of phase as the locomotive progresses down the track, but the two sets of engine sounds seem to stay locked in phase. I couldn't find anything in the Tsunami CD about it. Comments, anyone?

Thanks.

[Heave]

Well, for me the sounds are two sets of 4 beats until about 17 smph on the DCC. After that it's all a solid buzz of 4 beat at any speed to top.

I think the model is not a Compound because the cylinders are of the same size.

[JohnR]

This was debated on one of the Yahoo lists a month or so ago.  Since both sets of cylinders are receiving live steam, they wouldn't be out of phase typically.   This would imply that the out-of-the-box sound is okay. 

On the Soundtraxx blog, they mention a method for creating a second set of cylinder sounds using the reverb features of a Tsunami.  What's not known is if these features are present in the Bachmann OEM'd Tsunami.  This could also be used to "add sound" to a double header with a silent 2nd loco.

-John

[ksivils]

Given the locomotive is an articulated, not a Mallet in the true sense of the term, about the only way the two engines would get out of sync is if one engine slipped, probably the front engine due to less weight being present on that part of the locomotive.

My grandfather had some old vinyl records of Norfolk & Western Y6bs that were really cool.  You could hear the locomotive slipping one of the engines as it struggled up the grade with a heavy coal train.

If that effect could be reproduced in a DCC sound decoder, that would be truly cool!

[max (uk)]

I wish I could remember the exact CV for it. But I found it in the second half of the CD PDF.

I played around with the function, and in the end I changed it back to how it was. This is because each time you start the loco, both sets of cylinders sound at the same time. I did not like this as that's how it would sound most of the time on my small layout.

[ebtbob]

Ok,  I will admit it,  I do not know what you mean about the difference between articulated and mallet.

[hminky]

Ok,  I will admit it,  I do not know what you mean about the difference between articulated and mallet.

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

A simple doesn't re-use the steam and both cylinders are the same size.

Harold

[ebtbob]

Ok Harold,  so are you saying that the difference between an articulated and a mallet is the same as the difference between simple and compound articulated/mallet engines?  If so,  which one is the simple and which one is the compound?

[ksivils]

An easy visual way to see the difference would be to look at a photograph of one of Union Pacific's 4-8-8-4 Big Boys. These were simple articulated locomotives.  The cylinders are the same size.

Then take a look at a photograph of a Norfolk & Western Y6-b 2-8-8-2.  The front cylinders are HUGE.  The rear cylinders are much smaller (still huge though).  The Y6-bs were Mallets but they could be operated as simple articulated locomotives.

Hope this helps.

[ebtbob]

     Ok all,  let's get back to the original question I asked.   I asked,  what is the difference between articulated and a mallet?   I understand that some engines with two sets of drivers under one boiler have same sized cylinders and some with larger cylinders up front and small ones on the rear set of drivers.   That is the difference between simple and compound.  But..............again,   does the size of the cylinders make one engine an articulated engine as opposed to a mallet?  I thought that the two terms were interchangeable in reference to any engine with two sets of drivers under one boiler.

[ksivils]

Maybe I am not understanding the question.  A simple articulated locomotive has one boiler and two engines both of which are supplied high pressure steam through whatever cylinder arrangement that locomotive has.

A mallet has one boiler and two engines.  One engine is supplied high pressure steam to power the drivers.  The steam from that set of cylinders is then used as low pressure steam to drive the other, forward, engine.  This engine has the larger of the two sets of cylinders due to the use of low pressure steam.

The difference between a simple articulated and the Mallet is not in the type of cylinders used per se, but rather the re-using of steam from one set of cylinders to operate another.

Hopefully this answers your questions.

[ebtbob]

ksivils

      Ok,  once last question......you said a simple articulated........is there such a thing as a compound articulated,  as,  I said before,  my understanding is the word simple means two sets of cylinders of the same size.  So,  is there a compound articulated with two different sets of cylinders,  which by the way,  are necessary for the reuse of steam,  now low pressure,  by the larger front cylinders.

[ebtbob]

Good Evening All,

       I am not trying to beat a dead horse here.   I understand the terms simple and compound and the need for same or different sized cylinders under one boiler. 
       If I understand ksivils last reply to me,  an articulated engine would have the same size cylinders under the one boiler and the mallet would have two different sized cylinders.
       I just never heard the terms articulated and mallet used to describe engines with certain sized cylinders.   I always thought the two terms were interchangeable and the cylinder size was determined by how the steam was used in the two sets of drivers.

[ebtbob]

Good Evening All,  again

       Some on line searching lead me to the following information that basically states,   any engine built with articulation,  that has compound steam use is a true mallet.    If the same engine was to imploy simple steam use(same size cylinders) said engine is not a malley.   So,  again,  we have a simple misuse of terms that has been on going for quite a while now.   It has been an interesting discussion and I respect everyone being so patient with me.
       So here is the info I found in Widipedia :  Mallet's original design was a compound locomotive, in which the steam is used twice, first in a set of high-pressure cylinders, and then in a set of low-pressure cylinders. This confers certain thermodynamic advantages, and also worked well with the Mallet design. Steam was fed from the steam dome down to the aft, high-pressure cylinders - the exhaust steam from those being fed forwards in a pipe with a swiveling joint - to the forward, low-pressure cylinders. The exhaust steam from the larger low-pressure cylinders is exhausted through a slit in the sliding bearing in the top of the swiveling truck and thus to the smokebox above, and the blastpipe (US: exhaust nozzle) and chimney (US: stack). The difference in size between the high and low pressure cylinders can be seen in the picture of the 2-6-6-2 Mallet.

Unlike the case of the rigidly-framed locomotive, the Mallet design is easier to build as a compound, since steam and exhaust pipes are needed for both pairs of cylinders when it is built as a simple. When built as a compound, the only flexible steam pipes that are needed are the ones that deliver low-pressure steam from the rear cylinders to the front.
Simple expansion
Mallet's original patent specifies compound expansion. However many locomotives, particularly in the United States, were built to Mallet's articulation design but without employing compounding (for instance the Union Pacific Big Boy). The term "Mallet" is generally, if somewhat incorrectly, applied to locomotives built with the articulation system specified in the patent. Strictly, however, only compound locomotives are true Mallets[1].
      From your responses,  compared to the above I feel my question has been answered.



 

[Nick_Burman]

http://loggingmallets.railfan.net/export/ingenio9.htm

The Ingenio Angelina loco (the prototype for the B'mann loco) was a true Mallet (compound)... ergo the exhausts should only register 4 beats per revolution.


Cheers NB