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 and performance of a 12-volt dynamo for the 40/50 car model.
| Identifier | WestWitteringFiles\L\Jan1924-March1924\ Scan154 | |
| Date | 4th March 1924 | |
| X.294. SPECIFICATION OF ELECTRICAL OPERATION OF DYNAMO FOR WR. CAR. 40/50. (12 VOLT SYSTEM). The dynamo, after being run on load on the bench, clamped by means of metal clamps to an iron bed plate, for four hours with the commutator end cover in position, with a final ambient temperature not less than 18°C, and at a speed continually adjusted to secure maximum ampere output, and operating on a battery at a dynamo terminal voltage not less than 14.0, shall comply with the following :- (1) The temperature of the metal of the carcase, as measured by the insertion of a thermometer bulb in a little metal oil bath in good metallic contact with the carcase, shall not exceed 75° C. (2) The open circuit voltage of the machine immediately after this shall exceed 13.6 at a speed of 340 R.P.M.* (3) The output in this same hot condition shall exceed 10 amperes at an operating terminal voltage of 14.85 for the speed range 900 R.P.M. to 1500 R.P.M. and shall exceed 11 amperes at some speed in this range. Beyond this point, the exact shape of the ampere output speed curve is of less importance, but it is considered that a characteristic drooping somewhat (say to not less than 6 amperes at 3500 R.P.M.), with increase of speed is preferable to one which remains up at a high ampere value. (N.B. 1500 r.p.m. of dynamo corresponds, assuming the most normal, 15/52, axle ratio and a 1.5 dynamo drive ratio, approximately to 29 mp.h. road speed). ( For note * see bottom page ----) | ||