Instructions for maintaining, focusing, and aiming headlamp reflectors and bulbs.
| Identifier | ExFiles\Box 61a\1\ scan0379 | |
| Date | 1st January 1923 | |
| 3. THE REFLECTOR Reflectors which are used in Headlamps must have a Highly Polished Reflecting Surface of Silver, Glass, or Duralumin. If a reflector becomes tarnished it should be polished with fine silver polish, jeweller's rouge, or alcohol and lampblack on a piece of cotton batting. Polish by rubbing lightly from the bulb straight out to the rim. Do not use ordinary metal polish or coarse cloth. If the plating is worn off the reflector should be replaced. It is of the utmost importance not to leave the reflecting surface exposed to the weather, particularly in the case of silver-plated steel reflectors, which rust rapidly if exposed. Keep the packing between the rim of the reflector and the cover glass in place. It protects the reflector by keeping dust and moisture out. There should be a small hole in the bottom of the rim of the lamp. In replacing the rim be sure this hole is down, — it serves to drain the condensed moisture. In handling a reflector take hold of it by the rim. Never touch the reflecting surface with the fingers. If the lamp glass is broken, cover the lamp immediately with some weather-proof material which should be tied securely in place. Replace the broken glass as soon as possible. 4. THE ADJUSTMENT To be made on a level surface 25 feet from a wall or screen. FOCUSING THE BULB Provision is made in the ordinary automobile headlamp for moving the bulb forward and backward in the reflector. This is called the focusing adjustment. Usually it is what is known as the outside type (see Fig. 1). Turning the screw moves the bulb in the lamp. With the lenses installed and one lamp covered, turn the focusing screw in one direction or the other until the beam on the wall is as narrow as possible as in Fig. 2. Repeat this process with the other lamp. Fig. 3 shows how the beam looks when it is not focused properly. (Focus the upper beam of a tilting-beam headlamp.) When a bulb is replaced the lamp must be focused again. AIMING THE LAMP After the lamps are focused, and with the lenses installed, tip or bend them down, one at a time, until the top of the driving beam on the wall 25 feet away is a sufficient distance below the level of the centers of the lamps to take care of loading the car and slight spring action which is encountered on roads which are not perfectly smooth (see Fig. 2). The loading allowance should be made as follows: All pleasure cars with a single seat . . . . . . . . . . . . . . . . . . . . . . 3 in. Medium weight and heavy cars (5 or 7 pass.) . . . . . . . . . . . . . . 5 in. Light five passenger cars (wheelbase 110'' or less) . . . . . . . . . . . 7 in. This loading allowance is extremely important. Be sure and allow at least as much as that stated above with the car empty. A few light cars may require an 8 in. allowance. The aiming adjustment on buses and commercial vehicles should be made with a maximum load on, so that the top of the beam is two inches below the level of the lamp centers, plus one inch tilt in addition for every four inches higher than 42" that the lamps are mounted. PROCEDURE FOR HEADLAMP ADJUSTMENT 1. Place car on level surface so that the headlamps are 25 feet from the wall or screen. 2. Examine bulbs and reflectors. Repair or replace if necessary. 3. See that the lenses are installed so that they cannot turn in the lamp door. 4. Examine focusing mechanism. See that it works freely but will not jar out of adjustment. 5. Measure the distance from the floor to the centers of the lamps. Subtract the loading allowance and make a mark on the wall or set the cross-bar at that height on the uprights. 6. Light the lamps. Cover one at a time and focus the other. Always focus with the lenses in place if the lamps have an outside adjustment. 7. Aim the lamps so that the top of the beam on the wall comes even with the mark or cross-bar. FIG. 1. FOCUSING The bulb in most lamps is moved in or out by means of a screw in the back of the lamp case. FIG. 2 Beam from lamps which are properly focused and aimed on a wall 25 ft. away. Note the allowance for loading the car. Notice that the beam is narrow up and down. (This is how the upper beam of tilting-beam headlamps should appear). FIG. 3 The lamps are NOT focused. Notice how the beam spreads up and down. Copyright, 1923, by ALFRED W. DEVINE, Malden, Mass. | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).