Interpretation ID: 7018
Hella KG Hueck & Co.
Rixbecker Strae 75
Postfach 2840
4780 Lippstadt
Germany
Gentlemen:
This responds to your FAX of December 9, 1991, to Richard Van Iderstine of this agency. You ask for a definition of two and four headlamp systems, stating that formerly "this definition was done under para. S4.1.1.36, but today there only remains figure 26, which explains the application of photometric requirements with respect to the bulb or bulb combination used." You have enclosed sketches of three replaceable bulb headlighting systems and ask for confirmation that each is a two or four headlamp system under Standard No. 108.
Standard No. 108 has never contained a specific definition of two or four lamp headlamp systems. Paragraph S4.1.1.36 impliedly defined these systems for headlamps incorporating replaceable bulbs by specifying requirements for the upper and lower beams of headlamp systems consisting of two or four lamps, each containing one or two standardized replaceable light sources. When Standard No. 108 was amended to delete S4.1.1.36, these provisions became part of new paragraph S7.5 Replaceable Bulb Headlamp System. Figure 26 Table of Photometric Requirements was added to illustrate photometric requirements for headlighting systems that use combinations of replaceable bulbs listed in S7.6 Standardized Replaceable Light Sources, and as the systems are described in S7.5.
The understanding expressed in your drawings of replaceable bulb headlamp systems is correct. A 4-lamp system is one in which each lamp contains one light source, usually HB3 or HB4 light source for a total of two HB3 and HB4 light sources per system. A 2-lamp system is one in which each lamp typically contains a single dual filament light source such as HB1 or HB5, and achieves both a lower beam and an upper beam; alternatively, each lamp may contain two light sources, typically one HB3 and one HB4 light source, each with individual reflectors, but together with a common housing and lens. This lamp achieves both a lower and an upper beam.
Sincerely,
Paul Jackson Rice Chief Counsel
ref:108 d:3/5/92