This Standard specifies symbols for use in schematic diagrams for fluid power transmission and control systems in the general field of engineering excluding aircraft. Fluid power systems are those which use a fluid (liquid or gas) within enclosed circuits to transmit and control power. This Standard shows the basic symbols, describes the principles on which they are based, and illustrates some representative composite symbols. Composite symbols can be devised for any fluid power components by a combination of basic symbols. This Standard does not cover drawing office practice for the presentation of diagrams using the symbols, but it is recommended that such diagrams should be amplified by sufficient descriptive matter to indicate the sequence of operation and to aid in the definition of the particular component used. Section Three includes typical diagrams as examples. The symbols in Section One can also be used effectively for diagrams of lubrication systems.