Re: Parts of a locomotive I need some help with...

Very quickly John,
Tri-Cocks are three valves located on the backhead on the engineers side of the cab, they are placed at different levels (one higher than the other) and are another method for determining the water level in the boiler. They are not attached and have nothing to do with the sight glasses.
Valve Gear: on the K's it was Walschearts. This was one of the most common valve gears and was the easiest to time as all of the motion (links, etc.) are located on the outside of the frame and side rods. This was one of the earliest replacements for the Stephenson Valve Gear which had offset cams between the frame to provide the proper valve motion.
Foaming Water: Usually caused by impurities in the water, minerals, alkalai, whatever. I don't know about the C&TS, bu ton the UP, Rock Island, etc., there were water treatment plants where the water was unusually bad. On the UP in Medicine Bow and Bitter Creek, there were large "Water Softeners" located there. There was also one in Goodland (but bad water), Kansas on the Rock. The Water softeners were not uncommon. The three mentioned are just examples that I remember.
Most Steam operations now treat their water using treatment made by Nalco. So if you see a fireman throwing what looks like brown croquet balls in the tender, you'll know why.
As for running a K, I can't answer you, I've never run'em.
Rick Steele