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 the speedometer drive squares twisting off due to the load from a mechanically driven screen wiper.
| Identifier | ExFiles\Box 23\3\ Scan109 | |
| Date | 14th May 1927 | |
| To BY.{R.W. Bailey - Chief Engineer} from E.{Mr Elliott - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} X1087 E2/M14.5.27. RE. SPEEDOMETER DRIVE. X.8310 X.4308 X.1087 We understand from Mr. Evernden that trouble is being experienced with the speedometer drive squares twisting off when a mechanically driven screen wiper is employed. As you are no doubt aware, when this device is used, a small spur gearbox is fitted so that both speedometer and screen wiper cables can be driven from the same coupling on the chassis gearbox. We understand that as a rule the screen wiper takes very little power to drive it, but owing to the cable at times being twisted round sharp corners extra friction is created which throws too much load on the drive. The driving square shewn on drg. F.54523 is specified as .140 and it is pointed out that the B.E.S.A. std. for this dimension is .219". Also that we fit the AT. speedometer and the suppliers of this instrument are quoted as amongst those firms prepared to work to the B.E.S.A. standard. The point at issue therefore is can we increase the drive square to the B.E.S.A. standard? Personally I think the mechanically driven wiper is inferior to the electrical one, but I understand that RR. have recommended the former principally on account of its silence. E.{Mr Elliott - Chief Engineer} | ||