jim pastorius posted:I often wondered why poppet valves weren't adopted sooner on steam engines. According to a research article I read, the sliding valve like earlier steamers used weren't as efficient.
First, "slide valves" had to be replaced with spool valves, when superheating was developed and adopted. The older "slide valves" could NOT handle the seriously increased steam temperatures of superheated steam.
Maybe cost & maintenance was a factor ??
Absolutely! Maintenance of the poppet valve operating/drive system was higher maintenance, although probably offset by the increases in efficiency of steam usage.
