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).
Technical memorandum describing the operation of an auto switch and a potential issue with the cutout at high speeds.
| Identifier | ExFiles\Box 59\1\ Scan196 | |
| Date | 12th December 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} PN.{Mr Northey} GANMsee c. CWB. BY.{R.W. Bailey - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} X4008 EFC1/T2.12.27. AUTO SWITCH. When the auto switch resistance is, by operation of that switch, included in the field circuit, the E.M.F. of the dynamo has a much less rapid rise and fall with speed. It may happen, therefore, that when the auto switch operates at a fairly high speed, the cutout may not come out owing to insufficient reverse current back through the machine against its E.M.F. and further that the range of speed through which the cutout will remain in contact and allow a reverse current may be somewhat larger than in the normal case. The cutout does not take any more reverse current to cause it to operate than under standard conditions, but the reverse current may be shown over the larger range of speed. From the point of view of the automatic functioning of the system there would appear to be no objection to this small discharge on the battery existing for a short while when the battery is fully charged. The only real objection might be in the non-comprehension of the reason for this on the part of the driver, leading him to think erroneously that something was wrong. As against the above, we should remark here that with our present falling dynamo output characteristic at high speeds, (Contd) | ||