Headlamp: Difference between revisions - Wikipedia

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Headlight design in the U.S. changed very little from 1940 to 1983.<ref name="deepblue.lib.umich.edu"/><ref name="ridelust.com"/>

In 1940, a consortium of state motor vehicle administrators standardized upon a system of two {{convert|7|in|mm|0|abbr=on}} round [[sealed beam]] headlamps on all vehicles—the only system allowed for 17 years. A system of four round lamps, rather than two, one high/low and one high-beam {{convert|5+3/4|in|mm|0|abbr=on}} sealed beam on each side of the vehicle, was introduced inon some 1957 by Cadillac, Chrysler, DeSoto and Nash on some of their car models in states that permitted the new system. Other cars followed suit when all states permitted the new lamps by the time the 1958 [[Model year|models]] were brought to market. The four-lamp system permitted more design flexibility and improved low and high beam performance.<ref>{{cite journal |last1=Mead|first1=Howard|last2=Roper|first2=Val J.|date=October 1956|title=New 4-Lamp Dual Sealed-Beam Roadlighting System|journal=SAE Journal|pages=52-59}}</ref><ref>{{cite magazine |last=Rowsome|first=Frank Jr.|date=August 1956|pages=65-69|title=Why Cars are Going to Four Headlights|url=https://books.google.com/books?id=iSUDAAAAMBAJ&lpg=PA65&pg=PA65#v=onepage&q&f=false|magazine=Popular Science|access-date=14 March 2019}}</ref><ref>{{cite book |author=General Motors Research Laboratories in collaboration with lighting engineers of Guide Lamp Division|title=Optics and Wheels: a story of lighting from the primitive torch to the sealed beam headlamp|publisher=General Motors Public Relations Staff|pages=23-25|date=1965}}</ref> Auto stylists such as [[Virgil Exner]] carried out design studies with the low beams in their conventional outboard location, and the high beams vertically stacked at the centreline of the car, but no such designs reached volume production.

[[File:66marlinFastback white hood nameplate and headlights.jpg|thumb|5¾" sealed beam headlamps on a 1966 [[AMC Marlin]]]]