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).
Specification for the electrical operation of a cut-out, detailing voltage limits under cold and hot conditions.
| Identifier | ExFiles\Box 48\3\ Scan138 | |
| Date | 13th December 1920 | |
| Contd. -2- EFCl/T13.12.20. by the makers. X.3958 We attach for Mr. Olley's information a copy of specification of electrical operation of cut-out for R.R. car, which specifies the voltage at which the cut-out should operate both cold and hot. On the Lucas cut-out, however, it will be found that if the cold cutting-in voltage is adjusted to work between our limit 12.2 and 12.8, with the operating voltage when hot will probably be outside the range 13.2 to 14.2 at the top end. This is because the Lucas cut-out gets rather hotter than we like when in operation. It is undesirable to set the cut-out to cut in early under any conditions, i.e. at a boltage below that of the battery, because this tends to give the cut-out lever a dithering motion just at the point of cutting-in, due to the reverse series current throwing the contact off again. We therefore are of the opinion that if it is possible to make the adjustment, and this be properly carried out, it would be an advantage in some cases to adjust the Lucas cut-out to cut in when in the cold condition at 12.2 to 12.4 volts, but not less. The cutting-in speed in the hot condition may then be a little later than given by our limits, but if we were to adjust this so as to bring it within our limits in the hot condition, then the dithering effect spoken of might occur when the cut-out is cold. Hence, adjustment, when in the hot condition, to our limits would be undesirable. Contd. | ||