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).
Issues with speedometer illumination and proposing improvements to instrument design and grouping.
| Identifier | ExFiles\Box 62\2\ scan0350 | |
| Date | 28th February 1934 | |
| W/S. To Sg.{Arthur F. Sidgreaves - MD} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Ox. By/RD. Hs{Lord Ernest Hives - Chair}/WSt. 86135. E.4/HP.28.2.34. re Instruments. Nobody up here who has used the Terraplane much at night seems to like the illumination of the speedometer as carried out on this car. I think this must be because it is too bright and impedes the driving vision. The reason for this brightness being required may be due to the necessity for showing up the speedometer pointer through the semi transparent portion of the dial. This pointer is straight and the portion crossing the scale is not sufficiently different from the scale markings to stand out. A much better example of this form of illumination is fitted to the Pontiac Straight 8 on which the transparent scales are coloured green and no other light is allowed to come through the dial but that which shows the scales. The pointers moreover are fitted with large open arrow heads and the circular hole in the body of the arrow heads shows up much more plainly against the scale than a straight pointer would with the subdued illumination employed. It is possible in the case of the Pontiac that the instruments could be left on without impairing driving vision. The instruments are arranged on the semi-grouped scheme, there being three round dials, the centre one of which is reserved for the speedometer, and the outer two combining two instruments each, the scales being semi circular, arranged above and below a horizontal moulded bar across the face of the instrument, the finish and general appearance being very good. By/RD. has been developing a number of proposals for improving the grouping and illumination of our instruments on the latest lines, and we should like to discuss these with you when you are next in Derby. In all of these schemes we are retaining as far as possible the principle of using separate detachable instruments so that it is not necessary to take away the whole group should one instrument go wrong. This was one of the best things | ||