Train wheel

<p>A train wheel or rail wheel is a type of <a href="/facts/Wheel/SlIWX3xd">wheel</a> specially designed for use on <a href="/facts/Track_(rail_transport)/erncmXfX">railway tracks</a>. The wheel acts as a rolling component, typically <a href="/facts/Press_fit/cxqgTS4Q">press fitted</a> onto an <a href="/facts/Axle/Eo5jWI3f">axle</a> and mounted directly on a <a href="/facts/Railroad_car/4XBU36LV">railway carriage</a> or <a href="/facts/Locomotive/C9YV7wrQ">locomotive</a>, or indirectly on a <a href="/facts/Bogie/Q5060jts">bogie</a> (in the UK), also called a <i>truck</i> (in North America). The powered wheels under the locomotive are called <a href="/facts/Driving_wheel/9wTdcnDf">driving wheels</a>. Wheels are initially <a href="/facts/Casting/cFJ0hPuU">cast</a> or <a href="/facts/Forging/SYFomJNp">forged</a> and then heat-treated to have a specific hardness. New wheels are machined using a <a href="/facts/Lathe/FjF9FYLR">lathe</a> to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper <a href="/facts/Wheel-rail_interface/mLUYPm6C">interaction between the wheel and the rail</a>. Incorrectly profiled wheels and worn wheels can increase <a href="/facts/Rolling_resistance/nrvwxcHy">rolling resistance</a>, reduce <a href="/facts/Energy_efficiency_in_transport/XDpnWg7y">energy efficiency</a> and may even cause a <a href="/facts/Derailment/r1CjtzLa">derailment</a>. The <a href="/facts/International_Union_of_Railways/oSlgdIJk">International Union of Railways</a> has defined a standard wheel diameter of 920 mm (36 in), although smaller sizes are used in some <a href="/facts/Rapid_transit/bbhkQbAW">rapid transit</a> railway systems and on <a href="/facts/Rolling_highway/QxC4jS2r">ro-ro carriages</a>.
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Train wheel open-in-new

Train wheel