SAE J1939

Society of Automotive Engineers standard SAE J1939 is the vehicle bus recommended practice used for communication and diagnostics among vehicle components. Originating in the car and heavy-duty truck industry in the United States, it is now widely used in other parts of the world.

SAE J1939 is used in the commercial vehicle area for communication throughout the vehicle, with the physical layer defined in ISO 11898. A different physical layer is used between the tractor and trailer, specified in ISO 11992.

History

Originally, CAN was not mentioned in J1939, which covered cars and tractor-trailer rigs, and with some dual and triple use 8-bit addresses assigned by the SAE J1939 board. CAN was not originally free, but its instruction set did fit in the custom instruction format of J1939. This was true as of 2000. Since then, CAN has been included, the chipset for J1939 has been clocked faster, and 16-bit addresses (PGN) have replaced 8-bit addresses.

J1939, ISO 11783 and NMEA 2000 all share the same high level protocol. SAE J1939 can be considered the replacement for the older SAE J1708 and SAE J1587 specifications.

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List of copper alloys

Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both these are imprecise terms, both having been commonly referred to as lattens in the past. Today the term copper alloy tends to be substituted, especially by museums.

Composition

The similarity in external appearance of the various alloys, along with the different combinations of elements used when making each alloy, can lead to confusion when categorizing the different compositions. There are as many as 400 different copper and copper-alloy compositions loosely grouped into the categories: copper, high copper alloy, brasses, bronzes, copper nickels, copper–nickel–zinc (nickel silver), leaded copper, and special alloys. The following table lists the principal alloying element for four of the more common types used in modern industry, along with the name for each type. Historical types, such as those that characterize the Bronze Age, are vaguer as the mixtures were generally variable.

Spring steel

Spring steel is a name given to a wide range of steels used widely in the manufacture of springs, prominently in Automotive and Industrial suspension applications. These steels are generally low-alloy, medium-carbon steel or high-carbon steel with a very high yield strength. This allows objects made of spring steel to return to their original shape despite significant deflection or twisting.

Grades

Many grades of steel can be hardened and tempered to suit application as a spring, however some steels exhibit more desirable characteristics for spring applications.

Applications