The purpose of this album is to help you understand a part of the complex operation of a steam locomotive. The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust to escape, respectively, at the correct points in the cycle. It is sometimes referred to as the "motion."
There were two K5 Class 4-6-2 locomotives built. K5 #5698 was built at the PRR's Juniata Works (Juniata 4205 / 1929) and used conventional Walschaerts valve gear and piston valves.
K5 #5699 was built by Baldwin Locomotive Works (Baldwin 60660 / 1928 and used Caprotti Poppet Valves invented in Italy. The greater efficiencies of this gear gave the locomotive a higher tractive effort. Although efficient, the Caprotti gear proved less reliable than the regular Walscharets valve gear and requiring more frequent, more skilled maintenance, and in 1937 it was replaced by Walschaerts gear driving regular piston valves. As you can see by the following details the Caprotti gear was very complex. Hope this helps you understand one of the transitions in PRR steam power. If you would like set of high resolution images or prints let me know. MUSIC: Greg Karukas "Brooklyn Nights." Use View as Slideshow.