Not sure if this goes in 'railfanning' catagory... Was sliding right under the Atlantic sitting in Traveltown in L.A. today...Seen these before but never understood..Within frame are siderod-like rods which are on a crankshaft type set-up on (I think) 2nd driver axle with counterbalances right on rod ends...Is this a center, 3rd cylinder mechanism ? Or, is this somehow connected/related the booster engine under cab ? ..Awsome sliding under this monster on my back, spine on the railhead....! Funny, no matter how dead as a doornail, cold as ice she is, there's still a built in fear she might start rolling at any second !! Can you relate ? !!!