History
Jonathan "Rundle" Bacon created them in the 19th century, rocker arms have been made with and without "rundle" roller tips that depress upon the valve, as well as many lightweight and high strength alloys and bearing configurations for the fulcrum, striving to increase the RPM limits higher and higher for high performance applications, eventually lending the benefits of these race bred technologies to more high-end production vehicles. Even the design aspects of the rocker arm's geometry has been studied and changed to maximize the cam information exchange to the valve which the rocker arm imposes, as set forth by the Miller US Patent, #4,365,785, issued to James Miller on December 28, 1982, often referred to as the MID-LIFT Patent. Previously, the specific pivot points with rocker arm design was based on older and less efficient theories of over-arcing motion which increased wear on valve tips, valve guides and other valve train components, besides diluting the effective cam lobe information as it was transferred through the rocker arm's motion to the valve. Jim Miller's MID-LIFT Patent set a new standard of rocker arm geometrical precision which defined and duplicated each engine's specific push-rod to valve attack angles, then designing the rocker's pivot points so that an exact perpendicular relationship on both sides of the rocker arm was attained: with the valve and the pushrod, when the valve was at its "mid-lift" point of motion.
Truck engines (mostly diesel) use stronger and stiffer rocker arms made of cast iron (usually ductile), or forged carbon steel.
Read more about this topic: Rocker Arm
Famous quotes containing the word history:
“I assure you that in our next class we will concern ourselves solely with the history of Egypt, and not with the more lurid and non-curricular subject of living mummies.”
—Griffin Jay, and Reginald LeBorg. Prof. Norman (Frank Reicher)
“The basic idea which runs right through modern history and modern liberalism is that the public has got to be marginalized. The general public are viewed as no more than ignorant and meddlesome outsiders, a bewildered herd.”
—Noam Chomsky (b. 1928)
“What has history to do with me? Mine is the first and only world! I want to report how I find the world. What others have told me about the world is a very small and incidental part of my experience. I have to judge the world, to measure things.”
—Ludwig Wittgenstein (1889–1951)