Governor (device)

From Wikipedia, the free encyclopedia

A governor is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the Watt or fly-ball governor, which uses weights mounted on spring-loaded arms to determine how fast a shaft is spinning, and then uses proportional control to regulate the shaft speed.

1 Controversy
2 History
3 See also
4 References

[edit] Controversy

For road safety activists, the issue of speed governor settings on motor vehicles has become highly controversial. Nearly all motor vehicles on the market today have speed governors on them, but manufacturers are capping them at speeds of anywhere between 100 mph and 250 mph. Safety activists argue that there is no rational reason for setting speed governors on vehicles at speeds that are not only illegal anywhere in the nation but also unsafe. Why bother to crash-test occupant protection systems, including seatbelts and airbags, at maximum closing speeds of 40 mph, and then set the speed governors at well over 100 mph. Safety activists argue that speed governor settings should be tightly regulated by the federal government and should reflect the maximum safe speed at which vehicles can be operated.

Leading the charge for a federally mandated maximum speed governor setting in the U.S. is the non-profit Partnership for Safe Driving.www.crashprevention.org

[edit] History

The Gibbs Governor

Historically, in 1698 the first engine was built by the English engineer Thomas Savery. In 1769 the French engineer Nicolas Cugnot built the first pseudo-automobile, a steam-powered tricycle. Between the years 1775 and 1800 Scottish engineer James Watt in partnership with industrialist Matthew Boulton produced some 500 engines. At the heart of these engines was Watt’s self-designed “conical pendulum” governor, being a set of revolving steel balls attached to a vertical spindle by link arms, and where the controlling force consists of the weight of the balls.

Building on Watt’s design was American engineer Willard Gibbs who in 1872 theoretically analyzed Watt’s conical pendulum governor from a mathematical energy balance perspective. During his Graduate school years at Yale, Gibbs observed that the operation of the device in practice was beset with the disadvantages of sluggishness and a tendency to overcorrect for the changes in speed it was supposed to control.

Gibbs theorized that, analogous to the equilibrium of the simple Watt governor, which depends on the balancing of two torques: one due to the weight of the “balls” and the other due to their rotation, thermodynamic equilibrium for any work producing thermodynamic system depends on the balance of two entities: the heat energy supplied to and the work energy performed by the intermediate substance, in this case steam. These sorts of theoretical investigations culminated in the 1876 publication of the Gibbs' famous work On the Equilibrium of Heterogeneous Substances and in the construction of the Gibbs’ governor, shown adjacent. These formulations are ubiquitous today in the natural sciences in the form of the Gibbs' free energy equation, which is used to determine the equilibrium of chemical reactions; also known as Gibbs equilibrium.^[1]