Selection and design specifications for a speedometer and its drive mechanism.
| Identifier | ExFiles\Box 8\2\ 02-page07 | |
| Date | 1st May 1919 | |
| X613 Extract from -- E6/G1.5.19. X.1809. (4) SPEEDOMETER AND SPEEDOMETER DRIVE - The sample brought to West Wittering(Henry Royce's home town) of the Elliott speedometer, is very bulky and heavy. Since, however, Elliotts appear to be the only British instruments available and suitable, Mr. Royce instructs that we stick to their productions, but tell them that we do not want such an elaborate instrument as the trip-model, but the type fitted to 49 GB. is sufficient. 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 them 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. | ||
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).