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).
Wiper motor failure due to overheating, excessive current consumption, and component failure.
| Identifier | ExFiles\Box 59\3\ Scan235 | |
| Date | 6th March 1933 guessed | |
| -2- All the grease from the motor melted and ran out due to the excessive temperature. With regard to the wiper gearbox this also became overheated and the motor spindle and bearings became loose after 10 hours, while one of the cam pins was also affected after 12 hours and became loose. We note that the stalling current for this motor is excessively high i.e. 8 amperes, also the running current of this wiper under the condition described above was also considered high i.e. 4 to 5 amperes. Judging by the performance of this motor and its variation of current and speed with load we assume this motor is a series wound motor. We do not consider a series wound motor to be suitable for this job owing to :- (a) Its variations of speed with load. (b) Its high current consumption and high stalling current. For instance we cannot tolerate a dual wiper on our chassis which has a stalling current of more than 5 amperes and a running current under load conditions of 2 to 2.5 amperes. We consider you would obtain a much better result with a shunt wound machine. We are returning to you under separate cover the wiper in question for your examination and we shall be pleased if you will replace it with a new one complete in order that we can fit this to the chassis for which it was intended. At the same time we shall be glad to have your remarks on our tests above and what you propose to do with regard to reducing the current consumption of your Screen Wipers. Yours faithfully, FOR ROLLS ROYCE LIMITED. | ||