Skip to main content

Reply to "3 cylinder compound steam locomotives"

Originally Posted by morg777:

 My understanding of compounds is that the subsequent cylinders in a compound need to have twice the volume of the previous cylinder. 

 

The 2 to 1 ratio evidently worked pretty well on the 60000, but Mallet designers learned early on that a better ratio was about 2 1/2 to 1.  The ground-breaking Alco 2-6-6-2 that became the C&O H-1 of 1910 had that ratio, with high-pressure cylinders of 22" diameter, low-pressure cylinders of 35" diameter with a 32" stroke.  This ratio was also present on N&W's first Mallets, the X-1 0-8-8-0 and Y-1 2-8-8-2 of 1910, with their 24 1/2" high-pressure cylinders and 39" low-pressure cylinders with the 32" stroke. 

 

These cylinder dimensions were used on N&W's Y-2 2-8-8-2 of 1918 with a higher boiler pressure.  The USRA 2-8-8-2 modified this ratio by using a 25" high-pressure cylinder, and all N&W's subsequent 2-8-8-2s retained these cylinder dimensions.

 

EdKing 

 

OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

×
×
×
×
×