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 performance of Smith instruments, specifically the speedometer and clock, on the 20/25 chassis.
| Identifier | ExFiles\Box 178\4\ img089 | |
| Date | 13th May 1932 | |
| R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Wat. c. to Sa. c. to Wor.{Arthur Wormald - General Works Manager} c. to S. c. to Na.{Mr Nadin} c. to Hy.{Tom Haldenby - Plant Engineer} ORIGINAL Hs{Lord Ernest Hives - Chair}/Wat.l/MA.13. 5. 32. SMITH INSTRUMENTS ON R.R. 20/25 CHASSIS. X6135 We have now got these instruments reasonably satisfactory and we have run 4000 miles on the road irrespective of the mileage on 19-GR{George Ratcliffe}, with these instruments. Hs{Lord Ernest Hives - Chair}/Les.{Ivan A. Leslie} has carried out some road tests on these instruments in order to show up engine and road vibration effects etc., to good advantage. Speedometer. We have still retained the A.T. (which belongs to Smiths). This is a high class magnetic type of instrument and which has proved generally reliable. On a number of speedometers we have tested on a special synchronous speed rig we found these speedometers to be reading on the slow side, and we have taken up the matter with Smiths in order that customers shall not get hold of slow instruments. We have aimed at getting the mileometer portion dead correct and the speed indicator about 4% fast to allow for the drop in reading due to temperature rise and to combat the effects, which exist, of increase in effective tyre diameter due to wheel centrifugal force at high speeds. Clock. We have had to drop the electrically wound clock for the time being, because Smith's were not in a position to supply us with one. We have had no trouble with the ordinary wound time piece they have supplied. They have now bought up the Boyce Empire electric clock and they hope to supply us with improved Smith Empire electric clocks for test almost immediately. We shall then automatically bring these back on production later. | ||