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 operation and benefits of the Rolph Patent Automatic Traffic Warner system compared to hand signals.
| Identifier | ExFiles\Box 43\3\ Scan008 | |
| Date | 11th November 1921 guessed | |
| ROLPH PATENT AUTOMATIC TRAFFIC WARNER. Description—continued. The diagram B shows the method of signalling by the human arm. The driver of vehicle No. 1 holds out a hand which may mean one of three things—turning to the right or left, slow, stop. The signal is only seen by vehicle No. 2, as the angle of vision of vehicles Nos. 3 and 4 makes it impossible to see the hand, which, at most, projects only 14-in. If vehicle No. 1 is a large lorry or van, the chances of seeing the signal are very much lessened. It is impossible for the driver of vehicle No. 1 to indicate going to the left unless he has another person in the car to signal for him. AT NIGHT, HAND SIGNALS ARE ALMOST USELESS. The figures of cars in diagram A are shown equipped with the Rolph Automatic Traffic Warner. If vehicle No. 1 wants to slow up, turn to the right or left, or stop, no thought or hand action is required by the driver to warn the cars behind him, for, as he either slips his clutch, or slightly applies his footbrake, THAT INSTANT, the Warner shows the word SLOW, and ample warning is given to those behind. The word SLOW allows of no misunderstanding by anyone who can read. For purposes of signalling that the driver intends turning to the right or left, a lever is provided that is fixed on the steering column, which can be easily operated to show clearly the driver's intentions, to cars directly or obliquely behind him. The signals RIGHT and LEFT are shown by ARROWS on the Warner. Necessarily, before the driver can turn a corner, he has to slow up, and in slipping his clutch or slightly applying his footbrake, HE AUTOMATICALLY WARNS THE CARS BEHIND HIM. It would be mechanically an impossibility to have the direction signalled automatically, for indication of the driver's intended course must be made known some distance before the corner is reached. The signal STOP is shown automatically when the side brake is applied as in cases of emergency, or when the car is brought to a standstill. The device being mechanically and not electrically operated, can be relied on as being absolutely positive. A.{Mr Adams} B. | ||