It quite often happens that the owner of an automobile who has every intention of obeying the speed laws is brought into court simply because his chauffeur has exceeded instructions. It is such a temptation to put on a little more speed than is allowed and the excess will hardly be noticed by the owner unless his eye is on the speedometer. Sometimes, too, the driver will unconsciously increase the pace of the machine because, after riding for some time, the same speed seems slower than it did at the beginning of the run. As a safeguard against such violations of the law an automatic speed governor has been devised which places the control of the machine directly in the hands of the man . who is held responsible for its running. With this device the owner can set his machine to run at a predetermined speed and it will then be impossible for this speed to be exceeded. The accompanying diagram illustrates the device and shows how it is operated. At A is a speedometer of standard type which is electrically-connected with a circuit-breaker, B, through the switch, C. The latter is provided with five or more contacts respectively marked 10, 15, 20, etc., to indicate the miles per hour at which the. machine is set to run. The pointer of the switch may be turned to any one of these contacts. If, for instance, it be set .t 15 miles, the machine may run at any speed up to 15 mHes, *ut when this speed is reached the speedometer will automatically close the circuit through the switch contact 15 to the circuit-breaker B. This actuates the circuit-breaker through which passes the current to the primary of the induction coil, and thus cuts off the ignition current and shuts off the power. Another method is to have the circuit-breaker operate an electrically-controlled valve for shutting off the gas to the engine, when the car exceeds the speed at which the controlling switch was set. If the pointer on the controlling switch be set at an intermediate position, the device will impose no limits whatever on the speed of the car. In use the switch may be located within reach of the occupant of the tonneau or limousine, giving him entire control of the speed at which the vehicle may be operated and thereby permitting him to curb the recklessness of the chanffeur. By placing the control of the. speed of a car entirely in the owner's hanels, this device should add to the safety of those who employ thauffeurs.
This article was originally published with the title "Automatic Speed Governor" in Scientific American 97, 19, 332 (November 1907)