Awhile back, someone sent me the picture below of a Korean steam locomotive preserved in the Railway Museum in Bugok (nr Seoul), South Korea. Notice that it has a single cylinder air pump AND a cross-compound air pump.
I thought this odd pairing was unique to this particular steam locomotive until I started studying the pictures in Don Ross' collection. It turns out that most, if not all of the locomotives pictured in this class had this same combination.
I have no idea why Korean (later South Korean) Railways did this. I haven't seen this odd pairing anywhere else.
-James Hefner
Hebrews 10:20a