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 comparison of various electrical drive and transmission systems, including Owen-Magnetic, Frazer, and Tilling-Stevens types.
| Identifier | ExFiles\Box 52\3\ Scan368 | |
| Date | 1st August 1919 | |
| Oy10-F28/8/19-2 (b) The "Owen-Magnetic" type, which consists virtually of a magnetic engine clutch, in which the watts generated by slip are utilized in assisting the drive to the back axle, instead of being wasted in resistance. 5. Type "A" introduces the double loss of electric power due to the resistances and hysteresis of both the generator and motor, which are each dealing with the full engine power. 6. Type "B" has faults in the great variation of current in the conductors and necessitates a sliding gear box (in addition to the two electrical units) for first speed and reverse. Both types require at least two electric units and are consequently heavy. 7. The Frazer drive is of the "Tillings-Stevens" type, in that all the engine power is converted into watts and then turned back into foot pounds. The two electrical units are combined into one, and the stationary field magnets are placed in the middle of the two hollow revolving armatures, this saving weight. 8. The Frazer controller system, as at present applied to a Cadillac car, allows the propeller shaft to run at speeds varying from one-third to a three times engine speed, with consequent possibilities of fuel economy due to the accelerated propeller shaft drive. In practice, for ordinary touring conditions, the foot throttle is held partially or fully open and the speed of the car is adjusted to absorb the power developed by the engine at this throttle opening, and at its most desirable revolution speed, by altering the setting of the electrical controller to suit the varying road conditions. The variation in speed ratio is obtained by a double pole on the field windings, combined with a peculiar winding of the "motor" armature, which is coupled direct to the propeller shaft. Below is a diagram of the device: | ||