Usage SA3 coupler
other countries extensive usage finland, rail transport in finland mongolia, rail transport in mongolia iraq, iraqi republic railways turkey, rail transport in turkey mauritania railway operated société nationale industrielle et minière cameroon, camrail gabon, trans-gabon railway (called willison coupler) some usage sweden & norway (malmbanan/ofotbanen); used exclusively heavy iron-ore trains. australia; miniature sa3 used on sugarcane tramways , underground colliery railways. slovakia (uzhhorod–košice broad-gauge track); heavy iron-ore transports ukraine. poland (broad gauge metallurgy line); longest broad gauge railway line in poland. used freight traffic, iron ore , coal. united states willson coupler used in mining , tunneling railroads. ^ http://www.irwincar.com/couplers.php