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).
Letter to a supplier regarding overheating failures and a lack of temperature compensation on a combined dynamo cut out and regulator.
| Identifier | ExFiles\Box 166\1\ img102 | |
| Date | 24th June 1937 | |
| 6093 June 24th 1937 Lr{Mr Ellor}/Wst.20/AP. Messrs Joseph Lucas Ltd., Great King Street, BIRMINGHAM 19 For the attention of Mr. E.A. Watson. Dear Sirs, In connection with the testing we are now carrying out with the Lucas L.R.7.T. combined dynamo 'cut out' and regulator, we have found that the rise in operating voltage of the 'cut out' with rise of temperature is disconcertingly high. There is no noticeable temperature compensation on the 'cut out' unit and we have experienced failures of this unit to operate hot due to this cause. We must ask you either to provide temperature compensation on the 'cut out' or to rewind the shunt coil with a coarser gauge wire to reduce internal heating. We have proved that it is internal heating which is the cause as will be seen from an extract of Mr. Pignatt's report herewith:- "In connection with the falling output characteristic of the L.R.7.T. regulator, as the result of being over compensated, tests have been carried out on the car with the object of ascertaining the temperature reached at the outside of the regulator cover. Three tests were run, and in each case the failure of the 'cut out' to operate at normal speeds was taken as an indications of a definite condition of temperature. In the first test the car was run, and the 'cut out' checked at intervals, until failure occurred. At this point the temperature was observed, registered on a mercury glass stem thermometer, so fixed that the bulb was in close contact with the regulator cover. The temperature was 57°C. with an open air temperature of 24°C. continued | ||