1927-01-01

Head-Lamp Focusing Mechanisms and How They Affect Law Enforcement 270050

IT is common practice to provide single-filament motor-vehicle head-lamps with but one focus-adjusting mechanism. The advisability of incorporating also a vertical-focusing mechanism in two-filament tilting-beam head-lamps has been a subject of discussion.
The intent of State laws is to require the proper use of lighting equipment that meets the legal requirements. Focusing is the most difficult obstacle in the way of practical enforcement of the laws. Types of focusing mechanism are described and the effect of the use of each type on the instructions issued by State motor-vehicle departments is explained at some length.
Movement of the light source by the use of the different types of mechanism for focusing head-lamps is described to explain complications that attend the use of multiple adjusting-mechanisms. Head-lamps can be designed with a focal zone, instead of a focal point, so that they will be less sensitive to filament positioning. A sampling of bulbs in dealers' stocks shows that the variation in accuracy of commercial electric incandescent lamps is within the practical limits of compensated single-focus design.
Comparison is made between the adjustment of head-lamps in service which have one focusing-mechanism and two focusing-mechanisms. The deterrent effect of multiple-adjustment mechanisms on future development is discussed.
Proposals to rectify unsatisfactory night-driving conditions should be based upon the elimination of their primary causes. Various authorities agree with these views. The different uses of the vertical adjustment are considered.

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