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(last edited July 20, 2005) Front Page | Recent Changes | Title Index | User Preferences | Random Page | HelpThe principal control valve mounted on each vehicle fitted with air braking. So-called because it has three functions - to apply the brake, to hold the application at a constant level and to release and recharge the brake system. It also has (in its original form) three connections - to the brake pipe, to the brake cylinder and to the auxiliary reservoir.
Later versions of the original triple valve had a "quick acting" function brought into operation upon an emergency application or rapid discharge of brake pipe air. Recent developments have seen the original metallic valves replaced by flexible diaphragms and additional features like "quick release", "graduated release" and connections to emergency reservoirs added.
