Focusing and aligning
Align and focus headlamps with empty car standing on a level surface in front of a white wall or screen 25 feet from front of headlamps. This wall must be in semi darkness or sufficiently shielded from direct light so that the light L” spots from the headlamps can be clearly seen. The wall must be marked off with black lines as shown in Figs. 437 and 438. Details for making the lay out are shown in Fig. 439.
Turn on bright lights.
Focus by means of screw at back of lamps, keep one lamp covered while focusing the other. Adjust the bulb filament at the focal center of the reflector to obtain an elongated elliptical spot of light on the wall, with its long axis horizontal. (See Fig. 437.) In focusing, adjust the bulb to obtain as good contrast and as well defined cut-off across the top of the spot of light as possible.
With lamps thus focused for the “bright” filament, the “dim” will be in satisfactory position.
Loosen nut at bottom of bracket and tilt headlamps to desired angle.
The tops of the bright spots on the 25foot wall are to be set at a line 33 inches above level of surface on which car stands. With top lines thus set for empty car, the headlamps will also have the proper
tilt under full loads, as required by the various
The beam of light from each headlamp is to extend straight forward; that is, the centers of the elliptical spots of light must be 30 inches apart.
Proper alignment of headlamp is readily checked by means of a horizontal line on the wall in front of the car, 33 inches above the level surface on which car stands, and two vertical lines 30 inches apart, each one 15 inches from center line of car (see Fig. 439). Proper alignment of car relative to marks on the wall may be readily provided by use of wheel guide blocks for one side of the car, as shown in Fig. 439. If it is impossible to tie up the floor space required by these blocks, marks painted on the floor may be used to show where one set of wheels should track and where the car should be stopped. In order to avoid any confusion, the new layout can be painted with red paint and the old with black.