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).
Test report comparing Maconite H.T. ignition cable with a standard cable.
| Identifier | ExFiles\Box 168\1\ img008 | |
| Date | 3rd March 1926 | |
| EFC. WB.{Mr Brazier/Mr Bell}79. 3rd March 1926. X.86. MACONITE H.T. IGNITION CABLE. We have now submitted samples of this cable to a number of tests in conjunction with samples of H.T. cable at present used as standard on the cars. The various tests were as follows :- (1) 170 hrs. immersion in petrol. (2) 170 hrs. immersion in engine oil. (3) 170 hrs. immersion in 50% sulphuric acid. (4) Voltage breakdown test. In each case a sample of each cable was immersed. The results observed were as follows :- (1) 170 hrs. immersion in petrol. Both samples had rubber swollen about 100%. The outer rubber sheathing of the standard cable had burst in two placed, but the Maconite remained O.K. After drying in air for about 24 hrs. both samples shrank to their original dimensions. (2) 170 hrs. immersion in engine oil. A slight increase in size was observed in each case, and the surface of the rubber appeared plastic. (3) 170 hrs. immersion in 50% sulphuric acid. In the case of each sample no material change was observed due to the action of acid. (4) Voltage breakdown test. The Maconite cable was found to be capable of sustaining a peak voltage of 27400 volts applied to the insidew wire flex and the outer surface of the rubber for 3 mins. without breakdown. (This was the highest voltage obtainable on our H.T. transformer owing to low primary volts). With a sample of our standard cable, however, under the same conditions the voltage (27400) punctured the rubber insulation after 2 mins. duration. It will be seen from the above tests that the Maconite cable appears the better of the two, and we suggest making up a set of ignition wires from this cable and putting them on a car for test. EFC/H.E.West. | ||