"None of the regular suspects seems to have a hand in this, but essential reading is the steam shovel register which for various reasons seems to consist mainly of machines built on the west side of the Atlantic Ocean (added 14th May 2015). I saw one at work at the Beamish Museum, UK in April 2015, it was absolute magic. The remains of the railway Vulcan shovel at Fort Steel, British Columbia are well known.  There are several detail photos, including the builder's plate here - http://www.waymarking.com/waymarks/WMVKPW_Railway_Steam_Shovel_Fort_Steele_BC. "

This former Panama Canal shovel is at the Nederland Mining Museum, Colorado - for information see https://www.nederlandmuseums.org/miningmuseum.html. (Link broken by December 2023. RD) The pictures are courtesy of Kevin Hoggett.