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 features and test results of Hurley-Townsend Type 312 sparking plugs.
| Identifier | ExFiles\Box 58\2\ Scan033 | |
| Date | 24th February 1932 | |
| Copy. Rg.{Mr Rowledge} From Hs{Lord Ernest Hives - Chair}/Yng. c. to By.{R.W. Bailey - Chief Engineer} HS{Lord Ernest Hives - Chair}/Yng.1/AD24.2.32. HURLEY-TOWNSEND SPARKING PLUGS TYPE 312. Sparking plugs of the above type have recently been submitted for test purposes. They are manufactured by the Hurley-Townsend Corporation of New York and possess several novel and interesting features, the chief of which are: (1) A copper sleeve round the central electrode which is expanded outwardly against the mica laminations. It is claimed that very good heat conduction from the nose of the elctrode is obtained. (2) A centre electrode made of a special non-burning alloy which means that the plug is so balanced that the expansion of the central electrode and copper sleeve is greater than that of the plug shell and thus the gas tightness increases as the plug gets hotter. (3) A closed-end shell in which the spark gap takes the form of a hole surrounding the control electrode. This gives a greater area of side electrode i.e. a greater burning area, than the more usual point electrode which it is claimed make adjustments practically unnecessary. When, due to burning away, servicing of the spark gap becomes essential, this is done in a very quick and easy manner. The closed end of the shell is removed and replaced by a new one which is secured in position by a special welding process. Results of Tests. We have tested these plugs in a fully supercharged Kestrel engine (6 : 1 C.R.) under varying conditions of load at speeds between 2000 and 3000 R.P.M., at B.M.E.P's ranging from 107 - 153 lbs/sq.in. and have experienced no trouble with them. The total running time was 12 hrs. of which 1 1/2 hrs. was endurance running under conditions of very heavy detonation. From our test we should say that they appear to be perfectly satisfactory both as regards freedom from oiling up and ability to withstand heat, but at the same time we wish to point out that we have not had the opportunity of subjecting them to any lengthy duration running. Hs{Lord Ernest Hives - Chair}/Yng. | ||