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).
The development, challenges, and standardization of direction signal systems for passenger cars.
| Identifier | ExFiles\Box 113\3\ scan0142 | |
| Date | 15th January 1940 guessed | |
| - 3 - In initiating the use of direction signals for standard equipment on passenger cars we, at Buick, were confronted with several problems -- some of which will be of interest - (1) Since none of the above signals had been in general use, it was felt that a system must be chosen that would carry an obvious meaning to the public. It was decided that this called for the use of arrows, and from experiments made - that the arrow should be caused to flash. A study was made of arrow shapes and the optics involved. The pattern chosen proved to be the most effective for the size and shape of the lamp. (2) It was necessary to provide a unit that would be acceptable in appearance. A design was worked out which harmonized agreeably with the car, and was somewhat unusual in that undue bulk was eliminated by placing the bulbs on the underneath side of the trunk lid{A. J. Lidsey}, which was provided with suitable openings for illumination. It was further decided that this system would not only make its purpose obvious, but there were no exposed moving parts such as are present with the semaphore type, which might be effected by sleet and snow. It was reasonably economical and thus seemed to serve our purpose best. Direction signals of this type have now been in general use for nearly two years, and other systems involving flashing of the stop lights on the outer extremities of the vehicle have also come into use. With this as evidence of the serious consideration that is now being given to this subject, it is felt that a standardization program should be initiated by the industry. This will prevent confusion and forestall unfavorable legislative action. It is proposed that future developments embody the placement of signals, as near as possible, to the four extremities of the vehicle, irrespective of whether or not arrows are used. The reaction recently obtained from several prominent enforcement officials has indicated a preference for the location recommended, and use of arrows. However, in some instances those who have looked with disfavor on the non-arrow type, are becoming more receptive in view of increased usage and evidence of public understanding. The use of arrows, of course, requires separating the unit from the stop signal. "Type of Flashers and Use of Pilot Lights for Indicating Signal Operation": An important phase of this subject, and one that should also be given consideration in the standardization program, is the operation and location of the pilot light or lights to indicate to the driver whether or not the front and rear signals are operating. This is being stressed for the reason that flasher designs have been proposed, in which a failure of one or the other of the signals, would be indicated only by a speeding up or slowing down in the rate of flash. Inasmuch as there are other factors that also vary the rate of flash, such as difference in voltage, which varies with the engine speed, it is suggested that only those flasher designs, which produce a straight forward indication of the pilot bulb, by not lighting whenever either front or rear signal bulb is burned out, should be considered. Hence, only systems functioning in this manner are herein referred to. Experience has shown that a means to indicate to the driver the direction in which his signals are operating, is desirable. This can be accomplished mechanically by a suitable indicator on the switch lever, or better, by use of two pilot lights operating behind arrows on the instrument board. Upon the choice of these principals | ||