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).
Design of the speedometer drive and the finish of instrument controls.
| Identifier | ExFiles\Box 181\M11\ img177 | |
| Date | 1st May 1919 | |
| (4) SPEEDOMETER AND SPEEDOMETER DRIVE (CONTD.) It is understood with regard to the speedometer drive that a design is in hand by Mr. Bailey in Derby. Mr. Royce thinks that even the first chassis can be prepared to receive this new drive, which could be hung on at the last minute. Mr. Royce proposes that by using equal pulleys a vee belt could be employed for driving the speedometer from the present position behind the gear box. The gearing in the drive should be altered to suit the axle ratio on the car if any variation occurs here. As shewn in the diagram, a vee pulley should be carried by a shaft on which a small spur pinion is cut in the solid. This shaft would be run on ball bearings. The pinion would mesh with a large gear of approximately 1 to 4 ratio, for driving a flexible shaft to the instrument. The swivel pin on which the gear box is hung Would be placed very close to the big gear. The whole would then be carried on a suitable arm attached to the chassis frame, and be controlled by a suitable spring and stops. Would Mr. Bailey kindly go over these points to see that they are incorporated in the design. As specified later, the speedometer occupies a place on the instrument board to the left of the driver, and the cable comes down on the left of the car, and should dive right under the change speed gear box to get to its own reduction gear. (5) FINISH OF INSTRUMENTS AND CONTROLS. X3424 For instrument dials Mr. Royce prefers the white letters on a black ground, and approves of the Weston standard black dials with silver (Contd.) | ||