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).
Comparison report between Lucas and Smith manufactured warning lights.
| Identifier | ExFiles\Box 168a\1\ img134 | |
| Date | 27th April 1939 | |
| 6135 To By.{R.W. Bailey - Chief Engineer} from RM{William Robotham - Chief Engineer}/KC. C. to By/RD. RM{William Robotham - Chief Engineer}/KC.9/JH.27.4.39. Comparison Between Lucas & Smith warning Lights. We have received from the Drawing Office, for examination and test, two warning lights (one red for ignition, and the other green for fuel) made by Messrs. Smith & Sons Ltd., These have been examined by us, and compared with the corresponding Lucas unit, preparatory to test. Body of the lamp. The case of the smith lamp is of much lighter and probably cheaper construction than that of the Lucas. It is made of very thin sheet steel bent into a tube, the construction being sufficiently elastic to keep the edges along the joint, normally together. On the other hand the case of the Lucas lamp is made of brass, and is thick enough to take a thread cut on the outside for the fixing nut, and one on the inside at the open end into which is screwed the window frame. The Smith method however, appears to be quite strong enough for the purpose and has the advantage of being lighter. Method of fixing. Here again, the Lucas method of securing the lamp to the instrument board is perhaps more positive, the clamping being obtained by means of a nut running on the outside of the case, as compared with the Smith method of a spring held in compression against the back of the instrument board. Lamp Holder. The lamp holder in the Smith unit is decidedly superior to that in the Lucas unit. The lamp is held more firmly against the contacts and the terminals isolated from each other in such a manner that they cannot accidentally be short-circuited. Removal of the lamp bulb may also prove simpler with the Smith lamp, in spite of the fact that it has to be taken from behind the instrument board, whereas with the Lucas lamp it is taken from the front. Lamps rated at 12 volts 2.4 watts have been supplied with the Smith units, apparently by mistake. | ||