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).
The development and testing of new spark plugs, including different materials and compensating washers to prevent gas leakage.
| Identifier | ExFiles\Box 27\3\ Scan257 | |
| Date | 10th October 1939 guessed | |
| - 3 - In view of the undoubted advantages to be gained by use of a silver or possibly copper moulded centre insulator Messrs. K.L.G. and Lodge have been requested to undertake to produce some standard types of plug with the new electrode materials and it is anticipated that these will be available for trial within a few days time, when it is intended to test them and issue a report on their behaviour under various engine conditions. It is felt that the introduction of these new type of plugs should be pressed forward with all speed, if they are found to satisfy expectations, particularly in view of the new emergency conditions which it is proposed to introduce on certain standard types of engine. -------- A further development of the A.C. plug which may be adapted with advantage to other types of sparking plug is the introduction of a compensating washer in order to overcome the disadvantage of different rates of expansion between the various parts of the Sintercorund plug. It will be realised that the variation between the coefficients of expansion of steel and Sintercorund are considerable and without some form of compensation may lead to faulty seating of the insulator in the plug body. This may therefore give rise to gas leakage under working conditions, resulting in overheating of the sparking plug. It has been decided therefore to carry out a series of tests on all three manufacturers sparking plugs under engine conditions with a view to obtaining the gas leakage figure under hot conditions. It is also hoped that proof of the value of the compensating washer will be obtained by this test. As soon as the tests are completed a full report will be issued and if the fitting of a compensating washer is considered necessary to reduce gas leakage under working conditions, Messrs. K.L.G. and Lodge will be requested to fit this modification. -------- Lr{Mr Ellor}/Wst/J.Marsden. | ||