LGB 26842 Saxon Meyer

[Zerogee]

I've just consulted my copy of "Schmalspurbahnen in Sachsen" (Erich and Reiner Preuss), the IVk is clearly shown in several diagrams and many photos as having smaller diameter cylinders on the rear unit (high pressure) and large ones on the front (low pressure), and they are captioned thus in the photos; so definitely a compound, and definitely different cylinder sizes as per the LGB models.
As Stockers noted, equal cylinder size and a fixed rear frame is characteristic of a Mallet arrangement, not a Meyer.

Jon.

 

[Neil Robinson]

As Stockers noted, equal cylinder size and a fixed rear frame is characteristic of a Mallet arrangement, not a Meyer.

Jon.

<Pedant mode on> Not all Mallet's have equal sized cylinders, indeed the original patent was for compound locos. Some of the later, large, very high power locos such as the Union Pacific Challengers and Big Boys have four equally sized simple cylinders.
With compound Mallets, mounting the smaller high pressure cylinders on the fixed rear permits rigid high pressure steam pipes. Also the smaller cylinders may still be within the loading gauge when outside frames are used. This in turn gives more room for the grate and lower firebox.
For efficient use of the steam not only do the low pressure cylinders need to be larger than the high pressure ones but so do the valves. As there's no firebox in the way the use of inside frames makes sense at the front.
With few exceptions (e.g. Andre Chapelon) the development of superheating took away the need for compounding of locos.
<Pedant mode off>

 

[Zerogee]

<Pedant mode on> Not all Mallet's have equal sized cylinders, indeed the original patent was for compound locos. Some of the later, large, very high power locos such as the Union Pacific Challengers and Big Boys have four equally sized simple cylinders.
With compound Mallets, mounting the smaller high pressure cylinders on the fixed rear permits rigid high pressure steam pipes. Also the smaller cylinders may still be within the loading gauge when outside frames are used. This in turn gives more room for the grate and lower firebox.
For efficient use of the steam the not only do the low pressure cylinders need to be larger than the high pressure ones but so do the valves. As there's no firebox in the way the use of inside frames makes sense at the front.
With few exceptions (e.g. Andre Chapelon) the development of superheating took away the need for compounding of locos.
<Pedant mode off>

I bow in awe to your superior pedantry, Neil, and stand corrected......
I was half-right about the fixed rear frames, anyway.

Jon.

 

[palmerston]

There is no visable difference in size between front and back cilinders. ON the LGB and Regner´s livesteam model the backcilinders protude outside the loco´s body. On the real loco they are within the width of the water tanks. So, LGB and Regner fooled us. No compound!

Thread drift mode OFF

 

[stockers]

What! On page 3, your optimistic.