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).
Comparing the performance of Westinghouse and Bijur starting motors on the 4-EX model.
| Identifier | ExFiles\Box 168b\2\ img046 | |
| Date | 11th August 1920 | |
| H.M. v/35a (100 T) (N) H 149. 11-8-20 (I.150) -2- Contd. We subsequently ran 4-EX for a long time with the original Westinghouse starting motor and the SJW battery, and found that under all conditions of very cold engine, after the car had been left in the open all night in March, it was possible to spin the engine readily. This was with the original Westinghouse starting motor, the torque of which rose very slowly and very late as compared with the amps consumed. (See blue print No.1 enclosed, of which you already have a copy). With the new Westinghouse outfit on 4-EX with thick starter cable and the SJFN-28 battery (rubber seperators) the starting of the engine, even in very cold weather, is quite satisfactory. As shown by the Westinghouse test records, the current consumed by the starting motor has been reduced from about 300 to about 110 by the change in the starting motor, while the engine R.P.M. are actually increased when the LXR battery is used and only reduced from 140 to 110 R.P.M. when the Willard battery is used. It should be borne in mind, however, that the Westinghouse starting motor is a 5" motor as against the Bijur 5-1/2" and the Rolls-Royce 6", and therefore the torque rise per current consumed is not as great in the Westinghouse as in the Bijur. To illustrate this I enclose a curve giving the comparative data for the Westinghouse and Bijur. The Westinghouse Co., however, have explained in their letter attached to my report on 4-EX that they do not consider a larger motor is necessary and that they are confident that the final motor they have given us will actually consume less Watt hours of energy than our own motor, and this statement is pretty accurately brought out by tests. In order to illustrate the voltage loss which we are suffering at present, due to the use of the LXR battery and thin cable, I am enclosing a separate curve of terminal volts at the motor obtained with various batteries and starter cable. You will notice that on all the power curves I have sent you recently, a standard line for voltage drop is included on the chart, this representing the terminal volts at the motor which are produced artificially in making the tests of the motor and which are supposed to represent approximately the terminal volts which should be obtained at the motor in practice. Contd. | ||